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A modern Music Player Daemon based on Rockbox open source high quality audio player
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1/*
2 * loopy.c:
3 *
4 * An implementation of the Nikoli game 'Loop the loop'.
5 * (c) Mike Pinna, 2005, 2006
6 * Substantially rewritten to allowing for more general types of grid.
7 * (c) Lambros Lambrou 2008
8 *
9 * vim: set shiftwidth=4 :set textwidth=80:
10 */
11
12/*
13 * Possible future solver enhancements:
14 *
15 * - There's an interesting deductive technique which makes use
16 * of topology rather than just graph theory. Each _face_ in
17 * the grid is either inside or outside the loop; you can tell
18 * that two faces are on the same side of the loop if they're
19 * separated by a LINE_NO (or, more generally, by a path
20 * crossing no LINE_UNKNOWNs and an even number of LINE_YESes),
21 * and on the opposite side of the loop if they're separated by
22 * a LINE_YES (or an odd number of LINE_YESes and no
23 * LINE_UNKNOWNs). Oh, and any face separated from the outside
24 * of the grid by a LINE_YES or a LINE_NO is on the inside or
25 * outside respectively. So if you can track this for all
26 * faces, you figure out the state of the line between a pair
27 * once their relative insideness is known.
28 * + The way I envisage this working is simply to keep a flip dsf
29 * of all _faces_, which indicates whether they're on
30 * opposite sides of the loop from one another. We also
31 * include a special entry in the dsf for the infinite
32 * exterior "face".
33 * + So, the simple way to do this is to just go through the
34 * edges: every time we see an edge in a state other than
35 * LINE_UNKNOWN which separates two faces that aren't in the
36 * same dsf class, we can rectify that by merging the
37 * classes. Then, conversely, an edge in LINE_UNKNOWN state
38 * which separates two faces that _are_ in the same dsf
39 * class can immediately have its state determined.
40 * + But you can go one better, if you're prepared to loop
41 * over all _pairs_ of edges. Suppose we have edges A and B,
42 * which respectively separate faces A1,A2 and B1,B2.
43 * Suppose that A,B are in the same edge-dsf class and that
44 * A1,B1 (wlog) are in the same face-dsf class; then we can
45 * immediately place A2,B2 into the same face-dsf class (as
46 * each other, not as A1 and A2) one way round or the other.
47 * And conversely again, if A1,B1 are in the same face-dsf
48 * class and so are A2,B2, then we can put A,B into the same
49 * face-dsf class.
50 * * Of course, this deduction requires a quadratic-time
51 * loop over all pairs of edges in the grid, so it should
52 * be reserved until there's nothing easier left to be
53 * done.
54 *
55 * - The generalised grid support has made me (SGT) notice a
56 * possible extension to the loop-avoidance code. When you have
57 * a path of connected edges such that no other edges at all
58 * are incident on any vertex in the middle of the path - or,
59 * alternatively, such that any such edges are already known to
60 * be LINE_NO - then you know those edges are either all
61 * LINE_YES or all LINE_NO. Hence you can mentally merge the
62 * entire path into a single long curly edge for the purposes
63 * of loop avoidance, and look directly at whether or not the
64 * extreme endpoints of the path are connected by some other
65 * route. I find this coming up fairly often when I play on the
66 * octagonal grid setting, so it might be worth implementing in
67 * the solver.
68 *
69 * - (Just a speed optimisation.) Consider some todo list queue where every
70 * time we modify something we mark it for consideration by other bits of
71 * the solver, to save iteration over things that have already been done.
72 */
73
74#include <stdio.h>
75#include <stdlib.h>
76#include <stddef.h>
77#include <string.h>
78#include <assert.h>
79#include <ctype.h>
80#ifdef NO_TGMATH_H
81# include <math.h>
82#else
83# include <tgmath.h>
84#endif
85
86#include "puzzles.h"
87#include "tree234.h"
88#include "grid.h"
89#include "loopgen.h"
90
91/* Debugging options */
92
93/*
94#define DEBUG_CACHES
95#define SHOW_WORKING
96#define DEBUG_DLINES
97*/
98
99/* ----------------------------------------------------------------------
100 * Struct, enum and function declarations
101 */
102
103enum {
104 COL_BACKGROUND,
105 COL_FOREGROUND,
106 COL_LINEUNKNOWN,
107 COL_HIGHLIGHT,
108 COL_MISTAKE,
109 COL_SATISFIED,
110 COL_FAINT,
111 NCOLOURS
112};
113
114enum {
115 PREF_DRAW_FAINT_LINES,
116 PREF_AUTO_FOLLOW,
117 N_PREF_ITEMS
118};
119
120struct game_state {
121 grid *game_grid; /* ref-counted (internally) */
122
123 /* Put -1 in a face that doesn't get a clue */
124 signed char *clues;
125
126 /* Array of line states, to store whether each line is
127 * YES, NO or UNKNOWN */
128 char *lines;
129
130 bool *line_errors;
131 bool exactly_one_loop;
132
133 bool solved;
134 bool cheated;
135
136 /* Used in game_text_format(), so that it knows what type of
137 * grid it's trying to render as ASCII text. */
138 int grid_type;
139};
140
141enum solver_status {
142 SOLVER_SOLVED, /* This is the only solution the solver could find */
143 SOLVER_MISTAKE, /* This is definitely not a solution */
144 SOLVER_AMBIGUOUS, /* This _might_ be an ambiguous solution */
145 SOLVER_INCOMPLETE /* This may be a partial solution */
146};
147
148/* ------ Solver state ------ */
149typedef struct solver_state {
150 game_state *state;
151 enum solver_status solver_status;
152 /* NB looplen is the number of dots that are joined together at a point, ie a
153 * looplen of 1 means there are no lines to a particular dot */
154 int *looplen;
155
156 /* Difficulty level of solver. Used by solver functions that want to
157 * vary their behaviour depending on the requested difficulty level. */
158 int diff;
159
160 /* caches */
161 char *dot_yes_count;
162 char *dot_no_count;
163 char *face_yes_count;
164 char *face_no_count;
165 bool *dot_solved, *face_solved;
166 DSF *dotdsf;
167
168 /* Information for Normal level deductions:
169 * For each dline, store a bitmask for whether we know:
170 * (bit 0) at least one is YES
171 * (bit 1) at most one is YES */
172 char *dlines;
173
174 /* Hard level information */
175 DSF *linedsf;
176} solver_state;
177
178/*
179 * Difficulty levels. I do some macro ickery here to ensure that my
180 * enum and the various forms of my name list always match up.
181 */
182
183#define DIFFLIST(A) \
184 A(EASY,Easy,e) \
185 A(NORMAL,Normal,n) \
186 A(TRICKY,Tricky,t) \
187 A(HARD,Hard,h)
188#define ENUM(upper,title,lower) DIFF_ ## upper,
189#define TITLE(upper,title,lower) #title,
190#define ENCODE(upper,title,lower) #lower
191#define CONFIG(upper,title,lower) ":" #title
192enum { DIFFLIST(ENUM) DIFF_MAX };
193static char const *const diffnames[] = { DIFFLIST(TITLE) };
194static char const diffchars[] = DIFFLIST(ENCODE);
195#define DIFFCONFIG DIFFLIST(CONFIG)
196
197/*
198 * Solver routines, sorted roughly in order of computational cost.
199 * The solver will run the faster deductions first, and slower deductions are
200 * only invoked when the faster deductions are unable to make progress.
201 * Each function is associated with a difficulty level, so that the generated
202 * puzzles are solvable by applying only the functions with the chosen
203 * difficulty level or lower.
204 */
205#define SOLVERLIST(A) \
206 A(trivial_deductions, DIFF_EASY) \
207 A(dline_deductions, DIFF_NORMAL) \
208 A(linedsf_deductions, DIFF_HARD) \
209 A(loop_deductions, DIFF_EASY)
210#define SOLVER_FN_DECL(fn,diff) static int fn(solver_state *);
211#define SOLVER_FN(fn,diff) &fn,
212#define SOLVER_DIFF(fn,diff) diff,
213SOLVERLIST(SOLVER_FN_DECL)
214static int (*(solver_fns[]))(solver_state *) = { SOLVERLIST(SOLVER_FN) };
215static int const solver_diffs[] = { SOLVERLIST(SOLVER_DIFF) };
216static const int NUM_SOLVERS = sizeof(solver_diffs)/sizeof(*solver_diffs);
217
218struct game_params {
219 int w, h;
220 int diff;
221 int type;
222};
223
224/* line_drawstate is the same as line_state, but with the extra ERROR
225 * possibility. The drawing code copies line_state to line_drawstate,
226 * except in the case that the line is an error. */
227enum line_state { LINE_YES, LINE_UNKNOWN, LINE_NO };
228enum line_drawstate { DS_LINE_YES, DS_LINE_UNKNOWN,
229 DS_LINE_NO, DS_LINE_ERROR };
230
231#define OPP(line_state) \
232 (2 - line_state)
233
234
235struct game_drawstate {
236 bool started;
237 int tilesize;
238 bool flashing;
239 int *textx, *texty;
240 char *lines;
241 bool *clue_error;
242 bool *clue_satisfied;
243};
244
245static const char *validate_desc(const game_params *params, const char *desc);
246static int dot_order(const game_state* state, int i, char line_type);
247static int face_order(const game_state* state, int i, char line_type);
248static solver_state *solve_game_rec(const solver_state *sstate);
249
250#ifdef DEBUG_CACHES
251static void check_caches(const solver_state* sstate);
252#else
253#define check_caches(s)
254#endif
255
256/*
257 * Grid type config options available in Loopy.
258 *
259 * Annoyingly, we have to use an enum here which doesn't match up
260 * exactly to the grid-type enum in grid.h. Values in params->types
261 * are given by names such as LOOPY_GRID_SQUARE, which shouldn't be
262 * confused with GRID_SQUARE which is the value you pass to grid_new()
263 * and friends. So beware!
264 *
265 * (This is partly for historical reasons - Loopy's version of the
266 * enum is encoded in game parameter strings, so we keep it for
267 * backwards compatibility. But also, we need to store additional data
268 * here alongside each enum value, such as names for the presets menu,
269 * which isn't stored in grid.h; so we have to have our own list macro
270 * here anyway, and C doesn't make it easy to enforce that that lines
271 * up exactly with grid.h.)
272 *
273 * Do not add values to this list _except_ at the end, or old game ids
274 * will stop working!
275 */
276#define GRIDLIST(A) \
277 A("Squares",SQUARE,3,3) \
278 A("Triangular",TRIANGULAR,3,3) \
279 A("Honeycomb",HONEYCOMB,3,3) \
280 A("Snub-Square",SNUBSQUARE,3,3) \
281 A("Cairo",CAIRO,3,4) \
282 A("Great-Hexagonal",GREATHEXAGONAL,3,3) \
283 A("Octagonal",OCTAGONAL,3,3) \
284 A("Kites",KITE,3,3) \
285 A("Floret",FLORET,1,2) \
286 A("Dodecagonal",DODECAGONAL,2,2) \
287 A("Great-Dodecagonal",GREATDODECAGONAL,2,2) \
288 A("Penrose (kite/dart)",PENROSE_P2,3,3) \
289 A("Penrose (rhombs)",PENROSE_P3,3,3) \
290 A("Great-Great-Dodecagonal",GREATGREATDODECAGONAL,2,2) \
291 A("Kagome",KAGOME,3,3) \
292 A("Compass-Dodecagonal",COMPASSDODECAGONAL,2,2) \
293 A("Hats",HATS,6,6) \
294 A("Spectres",SPECTRES,6,6) \
295 /* end of list */
296
297#define GRID_NAME(title,type,amin,omin) title,
298#define GRID_CONFIG(title,type,amin,omin) ":" title
299#define GRID_LOOPYTYPE(title,type,amin,omin) LOOPY_GRID_ ## type,
300#define GRID_GRIDTYPE(title,type,amin,omin) GRID_ ## type,
301#define GRID_SIZES(title,type,amin,omin) \
302 {amin, omin, \
303 "Width and height for this grid type must both be at least " #amin, \
304 "At least one of width and height for this grid type must be at least " #omin,},
305enum { GRIDLIST(GRID_LOOPYTYPE) LOOPY_GRID_DUMMY_TERMINATOR };
306static char const *const gridnames[] = { GRIDLIST(GRID_NAME) };
307#define GRID_CONFIGS GRIDLIST(GRID_CONFIG)
308static grid_type grid_types[] = { GRIDLIST(GRID_GRIDTYPE) };
309#define NUM_GRID_TYPES (sizeof(grid_types) / sizeof(grid_types[0]))
310static const struct {
311 int amin, omin;
312 const char *aerr, *oerr;
313} grid_size_limits[] = { GRIDLIST(GRID_SIZES) };
314
315/* Generates a (dynamically allocated) new grid, according to the
316 * type and size requested in params. Does nothing if the grid is already
317 * generated. */
318static grid *loopy_generate_grid(const game_params *params,
319 const char *grid_desc)
320{
321 return grid_new(grid_types[params->type], params->w, params->h, grid_desc);
322}
323
324/* ----------------------------------------------------------------------
325 * Preprocessor magic
326 */
327
328/* General constants */
329#define PREFERRED_TILE_SIZE 32
330#define BORDER(tilesize) ((tilesize) / 2)
331#define FLASH_TIME 0.5F
332
333#define BIT_SET(field, bit) ((field) & (1<<(bit)))
334
335#define SET_BIT(field, bit) (BIT_SET(field, bit) ? false : \
336 ((field) |= (1<<(bit)), true))
337
338#define CLEAR_BIT(field, bit) (BIT_SET(field, bit) ? \
339 ((field) &= ~(1<<(bit)), true) : false)
340
341#define CLUE2CHAR(c) \
342 ((c < 0) ? ' ' : c < 10 ? c + '0' : c - 10 + 'A')
343
344/* ----------------------------------------------------------------------
345 * General struct manipulation and other straightforward code
346 */
347
348static game_state *dup_game(const game_state *state)
349{
350 game_state *ret = snew(game_state);
351
352 ret->game_grid = state->game_grid;
353 ret->game_grid->refcount++;
354
355 ret->solved = state->solved;
356 ret->cheated = state->cheated;
357
358 ret->clues = snewn(state->game_grid->num_faces, signed char);
359 memcpy(ret->clues, state->clues, state->game_grid->num_faces);
360
361 ret->lines = snewn(state->game_grid->num_edges, char);
362 memcpy(ret->lines, state->lines, state->game_grid->num_edges);
363
364 ret->line_errors = snewn(state->game_grid->num_edges, bool);
365 memcpy(ret->line_errors, state->line_errors,
366 state->game_grid->num_edges * sizeof(bool));
367 ret->exactly_one_loop = state->exactly_one_loop;
368
369 ret->grid_type = state->grid_type;
370 return ret;
371}
372
373static void free_game(game_state *state)
374{
375 if (state) {
376 grid_free(state->game_grid);
377 sfree(state->clues);
378 sfree(state->lines);
379 sfree(state->line_errors);
380 sfree(state);
381 }
382}
383
384static solver_state *new_solver_state(const game_state *state, int diff) {
385 int i;
386 int num_dots = state->game_grid->num_dots;
387 int num_faces = state->game_grid->num_faces;
388 int num_edges = state->game_grid->num_edges;
389 solver_state *ret = snew(solver_state);
390
391 ret->state = dup_game(state);
392
393 ret->solver_status = SOLVER_INCOMPLETE;
394 ret->diff = diff;
395
396 ret->dotdsf = dsf_new(num_dots);
397 ret->looplen = snewn(num_dots, int);
398
399 for (i = 0; i < num_dots; i++) {
400 ret->looplen[i] = 1;
401 }
402
403 ret->dot_solved = snewn(num_dots, bool);
404 ret->face_solved = snewn(num_faces, bool);
405 memset(ret->dot_solved, 0, num_dots * sizeof(bool));
406 memset(ret->face_solved, 0, num_faces * sizeof(bool));
407
408 ret->dot_yes_count = snewn(num_dots, char);
409 memset(ret->dot_yes_count, 0, num_dots);
410 ret->dot_no_count = snewn(num_dots, char);
411 memset(ret->dot_no_count, 0, num_dots);
412 ret->face_yes_count = snewn(num_faces, char);
413 memset(ret->face_yes_count, 0, num_faces);
414 ret->face_no_count = snewn(num_faces, char);
415 memset(ret->face_no_count, 0, num_faces);
416
417 if (diff < DIFF_NORMAL) {
418 ret->dlines = NULL;
419 } else {
420 ret->dlines = snewn(2*num_edges, char);
421 memset(ret->dlines, 0, 2*num_edges);
422 }
423
424 if (diff < DIFF_HARD) {
425 ret->linedsf = NULL;
426 } else {
427 ret->linedsf = dsf_new_flip(state->game_grid->num_edges);
428 }
429
430 return ret;
431}
432
433static void free_solver_state(solver_state *sstate) {
434 if (sstate) {
435 free_game(sstate->state);
436 dsf_free(sstate->dotdsf);
437 sfree(sstate->looplen);
438 sfree(sstate->dot_solved);
439 sfree(sstate->face_solved);
440 sfree(sstate->dot_yes_count);
441 sfree(sstate->dot_no_count);
442 sfree(sstate->face_yes_count);
443 sfree(sstate->face_no_count);
444
445 /* OK, because sfree(NULL) is a no-op */
446 sfree(sstate->dlines);
447 dsf_free(sstate->linedsf);
448
449 sfree(sstate);
450 }
451}
452
453static solver_state *dup_solver_state(const solver_state *sstate) {
454 game_state *state = sstate->state;
455 int num_dots = state->game_grid->num_dots;
456 int num_faces = state->game_grid->num_faces;
457 int num_edges = state->game_grid->num_edges;
458 solver_state *ret = snew(solver_state);
459
460 ret->state = state = dup_game(sstate->state);
461
462 ret->solver_status = sstate->solver_status;
463 ret->diff = sstate->diff;
464
465 ret->dotdsf = dsf_new(num_dots);
466 ret->looplen = snewn(num_dots, int);
467 dsf_copy(ret->dotdsf, sstate->dotdsf);
468 memcpy(ret->looplen, sstate->looplen,
469 num_dots * sizeof(int));
470
471 ret->dot_solved = snewn(num_dots, bool);
472 ret->face_solved = snewn(num_faces, bool);
473 memcpy(ret->dot_solved, sstate->dot_solved, num_dots * sizeof(bool));
474 memcpy(ret->face_solved, sstate->face_solved, num_faces * sizeof(bool));
475
476 ret->dot_yes_count = snewn(num_dots, char);
477 memcpy(ret->dot_yes_count, sstate->dot_yes_count, num_dots);
478 ret->dot_no_count = snewn(num_dots, char);
479 memcpy(ret->dot_no_count, sstate->dot_no_count, num_dots);
480
481 ret->face_yes_count = snewn(num_faces, char);
482 memcpy(ret->face_yes_count, sstate->face_yes_count, num_faces);
483 ret->face_no_count = snewn(num_faces, char);
484 memcpy(ret->face_no_count, sstate->face_no_count, num_faces);
485
486 if (sstate->dlines) {
487 ret->dlines = snewn(2*num_edges, char);
488 memcpy(ret->dlines, sstate->dlines,
489 2*num_edges);
490 } else {
491 ret->dlines = NULL;
492 }
493
494 if (sstate->linedsf) {
495 ret->linedsf = dsf_new_flip(num_edges);
496 dsf_copy(ret->linedsf, sstate->linedsf);
497 } else {
498 ret->linedsf = NULL;
499 }
500
501 return ret;
502}
503
504static game_params *default_params(void)
505{
506 game_params *ret = snew(game_params);
507
508#ifdef SLOW_SYSTEM
509 ret->h = 7;
510 ret->w = 7;
511#else
512 ret->h = 10;
513 ret->w = 10;
514#endif
515 ret->diff = DIFF_EASY;
516 ret->type = 0;
517
518 return ret;
519}
520
521static game_params *dup_params(const game_params *params)
522{
523 game_params *ret = snew(game_params);
524
525 *ret = *params; /* structure copy */
526 return ret;
527}
528
529static const game_params loopy_presets_top[] = {
530#ifdef SMALL_SCREEN
531 { 7, 7, DIFF_EASY, LOOPY_GRID_SQUARE },
532 { 7, 7, DIFF_NORMAL, LOOPY_GRID_SQUARE },
533 { 7, 7, DIFF_HARD, LOOPY_GRID_SQUARE },
534 { 7, 7, DIFF_HARD, LOOPY_GRID_TRIANGULAR },
535 { 5, 5, DIFF_HARD, LOOPY_GRID_SNUBSQUARE },
536 { 7, 7, DIFF_HARD, LOOPY_GRID_CAIRO },
537 { 5, 5, DIFF_HARD, LOOPY_GRID_KITE },
538 { 6, 6, DIFF_HARD, LOOPY_GRID_PENROSE_P2 },
539 { 6, 6, DIFF_HARD, LOOPY_GRID_PENROSE_P3 },
540#else
541 { 7, 7, DIFF_EASY, LOOPY_GRID_SQUARE },
542 { 10, 10, DIFF_EASY, LOOPY_GRID_SQUARE },
543 { 7, 7, DIFF_NORMAL, LOOPY_GRID_SQUARE },
544 { 10, 10, DIFF_NORMAL, LOOPY_GRID_SQUARE },
545 { 7, 7, DIFF_HARD, LOOPY_GRID_SQUARE },
546 { 10, 10, DIFF_HARD, LOOPY_GRID_SQUARE },
547 { 12, 10, DIFF_HARD, LOOPY_GRID_TRIANGULAR },
548 { 7, 7, DIFF_HARD, LOOPY_GRID_SNUBSQUARE },
549 { 9, 9, DIFF_HARD, LOOPY_GRID_CAIRO },
550 { 5, 5, DIFF_HARD, LOOPY_GRID_KITE },
551 { 10, 10, DIFF_HARD, LOOPY_GRID_PENROSE_P2 },
552 { 10, 10, DIFF_HARD, LOOPY_GRID_PENROSE_P3 },
553#endif
554};
555
556static const game_params loopy_presets_more[] = {
557#ifdef SMALL_SCREEN
558 { 7, 7, DIFF_HARD, LOOPY_GRID_HONEYCOMB },
559 { 5, 4, DIFF_HARD, LOOPY_GRID_GREATHEXAGONAL },
560 { 5, 4, DIFF_HARD, LOOPY_GRID_KAGOME },
561 { 5, 5, DIFF_HARD, LOOPY_GRID_OCTAGONAL },
562 { 3, 3, DIFF_HARD, LOOPY_GRID_FLORET },
563 { 3, 3, DIFF_HARD, LOOPY_GRID_DODECAGONAL },
564 { 3, 3, DIFF_HARD, LOOPY_GRID_GREATDODECAGONAL },
565 { 3, 2, DIFF_HARD, LOOPY_GRID_GREATGREATDODECAGONAL },
566 { 3, 3, DIFF_HARD, LOOPY_GRID_COMPASSDODECAGONAL },
567 { 6, 6, DIFF_HARD, LOOPY_GRID_HATS },
568 { 6, 6, DIFF_HARD, LOOPY_GRID_SPECTRES },
569#else
570 { 10, 10, DIFF_HARD, LOOPY_GRID_HONEYCOMB },
571 { 5, 4, DIFF_HARD, LOOPY_GRID_GREATHEXAGONAL },
572 { 5, 4, DIFF_HARD, LOOPY_GRID_KAGOME },
573 { 7, 7, DIFF_HARD, LOOPY_GRID_OCTAGONAL },
574 { 5, 5, DIFF_HARD, LOOPY_GRID_FLORET },
575 { 5, 4, DIFF_HARD, LOOPY_GRID_DODECAGONAL },
576 { 5, 4, DIFF_HARD, LOOPY_GRID_GREATDODECAGONAL },
577 { 5, 3, DIFF_HARD, LOOPY_GRID_GREATGREATDODECAGONAL },
578 { 5, 4, DIFF_HARD, LOOPY_GRID_COMPASSDODECAGONAL },
579 { 10, 10, DIFF_HARD, LOOPY_GRID_HATS },
580 { 10, 10, DIFF_HARD, LOOPY_GRID_SPECTRES },
581#endif
582};
583
584static void preset_menu_add_preset_with_title(struct preset_menu *menu,
585 const game_params *params)
586{
587 char buf[80];
588 game_params *dup_params;
589
590 sprintf(buf, "%dx%d %s - %s", params->h, params->w,
591 gridnames[params->type], diffnames[params->diff]);
592
593 dup_params = snew(game_params);
594 *dup_params = *params;
595
596 preset_menu_add_preset(menu, dupstr(buf), dup_params);
597}
598
599static struct preset_menu *game_preset_menu(void)
600{
601 struct preset_menu *top, *more;
602 int i;
603
604 top = preset_menu_new();
605 for (i = 0; i < lenof(loopy_presets_top); i++)
606 preset_menu_add_preset_with_title(top, &loopy_presets_top[i]);
607
608 more = preset_menu_add_submenu(top, dupstr("More..."));
609 for (i = 0; i < lenof(loopy_presets_more); i++)
610 preset_menu_add_preset_with_title(more, &loopy_presets_more[i]);
611
612 return top;
613}
614
615static void free_params(game_params *params)
616{
617 sfree(params);
618}
619
620static void decode_params(game_params *params, char const *string)
621{
622 params->h = params->w = atoi(string);
623 params->diff = DIFF_EASY;
624 while (*string && isdigit((unsigned char)*string)) string++;
625 if (*string == 'x') {
626 string++;
627 params->h = atoi(string);
628 while (*string && isdigit((unsigned char)*string)) string++;
629 }
630 if (*string == 't') {
631 string++;
632 params->type = atoi(string);
633 while (*string && isdigit((unsigned char)*string)) string++;
634 }
635 if (*string == 'd') {
636 int i;
637 string++;
638 for (i = 0; i < DIFF_MAX; i++)
639 if (*string == diffchars[i])
640 params->diff = i;
641 if (*string) string++;
642 }
643}
644
645static char *encode_params(const game_params *params, bool full)
646{
647 char str[80];
648 sprintf(str, "%dx%dt%d", params->w, params->h, params->type);
649 if (full)
650 sprintf(str + strlen(str), "d%c", diffchars[params->diff]);
651 return dupstr(str);
652}
653
654static config_item *game_configure(const game_params *params)
655{
656 config_item *ret;
657 char buf[80];
658
659 ret = snewn(5, config_item);
660
661 ret[0].name = "Width";
662 ret[0].type = C_STRING;
663 sprintf(buf, "%d", params->w);
664 ret[0].u.string.sval = dupstr(buf);
665
666 ret[1].name = "Height";
667 ret[1].type = C_STRING;
668 sprintf(buf, "%d", params->h);
669 ret[1].u.string.sval = dupstr(buf);
670
671 ret[2].name = "Grid type";
672 ret[2].type = C_CHOICES;
673 ret[2].u.choices.choicenames = GRID_CONFIGS;
674 ret[2].u.choices.selected = params->type;
675
676 ret[3].name = "Difficulty";
677 ret[3].type = C_CHOICES;
678 ret[3].u.choices.choicenames = DIFFCONFIG;
679 ret[3].u.choices.selected = params->diff;
680
681 ret[4].name = NULL;
682 ret[4].type = C_END;
683
684 return ret;
685}
686
687static game_params *custom_params(const config_item *cfg)
688{
689 game_params *ret = snew(game_params);
690
691 ret->w = atoi(cfg[0].u.string.sval);
692 ret->h = atoi(cfg[1].u.string.sval);
693 ret->type = cfg[2].u.choices.selected;
694 ret->diff = cfg[3].u.choices.selected;
695
696 return ret;
697}
698
699static const char *validate_params(const game_params *params, bool full)
700{
701 const char *err;
702 if (params->type < 0 || params->type >= NUM_GRID_TYPES)
703 return "Illegal grid type";
704 if (params->w < grid_size_limits[params->type].amin ||
705 params->h < grid_size_limits[params->type].amin)
706 return grid_size_limits[params->type].aerr;
707 if (params->w < grid_size_limits[params->type].omin &&
708 params->h < grid_size_limits[params->type].omin)
709 return grid_size_limits[params->type].oerr;
710 err = grid_validate_params(grid_types[params->type], params->w, params->h);
711 if (err != NULL) return err;
712
713 /*
714 * This shouldn't be able to happen at all, since decode_params
715 * and custom_params will never generate anything that isn't
716 * within range.
717 */
718 assert(params->diff < DIFF_MAX);
719
720 return NULL;
721}
722
723/* Returns a newly allocated string describing the current puzzle */
724static char *state_to_text(const game_state *state)
725{
726 grid *g = state->game_grid;
727 char *retval;
728 int num_faces = g->num_faces;
729 char *description = snewn(num_faces + 1, char);
730 char *dp = description;
731 int empty_count = 0;
732 int i;
733
734 for (i = 0; i < num_faces; i++) {
735 if (state->clues[i] < 0) {
736 if (empty_count > 25) {
737 dp += sprintf(dp, "%c", (int)(empty_count + 'a' - 1));
738 empty_count = 0;
739 }
740 empty_count++;
741 } else {
742 if (empty_count) {
743 dp += sprintf(dp, "%c", (int)(empty_count + 'a' - 1));
744 empty_count = 0;
745 }
746 dp += sprintf(dp, "%c", (int)CLUE2CHAR(state->clues[i]));
747 }
748 }
749
750 if (empty_count)
751 dp += sprintf(dp, "%c", (int)(empty_count + 'a' - 1));
752
753 retval = dupstr(description);
754 sfree(description);
755
756 return retval;
757}
758
759#define GRID_DESC_SEP '_'
760
761/* Splits up a (optional) grid_desc from the game desc. Returns the
762 * grid_desc (which needs freeing) and updates the desc pointer to
763 * start of real desc, or returns NULL if no desc. */
764static char *extract_grid_desc(const char **desc)
765{
766 char *sep = strchr(*desc, GRID_DESC_SEP), *gd;
767 int gd_len;
768
769 if (!sep) return NULL;
770
771 gd_len = sep - (*desc);
772 gd = snewn(gd_len+1, char);
773 memcpy(gd, *desc, gd_len);
774 gd[gd_len] = '\0';
775
776 *desc = sep+1;
777
778 return gd;
779}
780
781/* We require that the params pass the test in validate_params and that the
782 * description fills the entire game area */
783static const char *validate_desc(const game_params *params, const char *desc)
784{
785 int count = 0;
786 grid *g;
787 char *grid_desc;
788 const char *ret;
789
790 /* It's pretty inefficient to do this just for validation. All we need to
791 * know is the precise number of faces. */
792 grid_desc = extract_grid_desc(&desc);
793 ret = grid_validate_desc(grid_types[params->type], params->w, params->h, grid_desc);
794 if (ret) {
795 sfree(grid_desc);
796 return ret;
797 }
798
799 g = loopy_generate_grid(params, grid_desc);
800 sfree(grid_desc);
801
802 for (; *desc; ++desc) {
803 if ((*desc >= '0' && *desc <= '9') || (*desc >= 'A' && *desc <= 'Z')) {
804 count++;
805 continue;
806 }
807 if (*desc >= 'a') {
808 count += *desc - 'a' + 1;
809 continue;
810 }
811 grid_free(g);
812 return "Unknown character in description";
813 }
814
815 if (count < g->num_faces) {
816 grid_free(g);
817 return "Description too short for board size";
818 }
819 if (count > g->num_faces) {
820 grid_free(g);
821 return "Description too long for board size";
822 }
823
824 grid_free(g);
825
826 return NULL;
827}
828
829/* Sums the lengths of the numbers in range [0,n) */
830/* See equivalent function in solo.c for justification of this. */
831static int len_0_to_n(int n)
832{
833 int len = 1; /* Counting 0 as a bit of a special case */
834 int i;
835
836 for (i = 1; i < n; i *= 10) {
837 len += max(n - i, 0);
838 }
839
840 return len;
841}
842
843static char *encode_solve_move(const game_state *state)
844{
845 int len;
846 char *ret, *p;
847 int i;
848 int num_edges = state->game_grid->num_edges;
849
850 /* This is going to return a string representing the moves needed to set
851 * every line in a grid to be the same as the ones in 'state'. The exact
852 * length of this string is predictable. */
853
854 len = 1; /* Count the 'S' prefix */
855 /* Numbers in all lines */
856 len += len_0_to_n(num_edges);
857 /* For each line we also have a letter */
858 len += num_edges;
859
860 ret = snewn(len + 1, char);
861 p = ret;
862
863 p += sprintf(p, "S");
864
865 for (i = 0; i < num_edges; i++) {
866 switch (state->lines[i]) {
867 case LINE_YES:
868 p += sprintf(p, "%dy", i);
869 break;
870 case LINE_NO:
871 p += sprintf(p, "%dn", i);
872 break;
873 }
874 }
875
876 /* No point in doing sums like that if they're going to be wrong */
877 assert(strlen(ret) <= (size_t)len);
878 return ret;
879}
880
881struct game_ui {
882 /*
883 * User preference: should grid lines in LINE_NO state be drawn
884 * very faintly so users can still see where they are, or should
885 * they be completely invisible?
886 */
887 bool draw_faint_lines;
888
889 /*
890 * User preference: when clicking an edge that has only one
891 * possible edge connecting to one (or both) of its ends, should
892 * that edge also change to the same state as the edge we just
893 * clicked?
894 */
895 enum {
896 AF_OFF, /* no, all grid edges are independent in the UI */
897 AF_FIXED, /* yes, but only based on the grid itself */
898 AF_ADAPTIVE /* yes, and consider edges user has already set to NO */
899 } autofollow;
900};
901
902static void legacy_prefs_override(struct game_ui *ui_out)
903{
904 static bool initialised = false;
905 static int draw_faint_lines = -1;
906 static int autofollow = -1;
907
908 if (!initialised) {
909 char *env;
910
911 initialised = true;
912 draw_faint_lines = getenv_bool("LOOPY_FAINT_LINES", -1);
913
914 if ((env = getenv("LOOPY_AUTOFOLLOW")) != NULL) {
915 if (!strcmp(env, "off"))
916 autofollow = AF_OFF;
917 else if (!strcmp(env, "fixed"))
918 autofollow = AF_FIXED;
919 else if (!strcmp(env, "adaptive"))
920 autofollow = AF_ADAPTIVE;
921 }
922 }
923
924 if (draw_faint_lines != -1)
925 ui_out->draw_faint_lines = draw_faint_lines;
926 if (autofollow != -1)
927 ui_out->autofollow = autofollow;
928}
929
930static game_ui *new_ui(const game_state *state)
931{
932 game_ui *ui = snew(game_ui);
933 ui->draw_faint_lines = true;
934 ui->autofollow = AF_OFF;
935 legacy_prefs_override(ui);
936 return ui;
937}
938
939static void free_ui(game_ui *ui)
940{
941 sfree(ui);
942}
943
944static config_item *get_prefs(game_ui *ui)
945{
946 config_item *ret;
947
948 ret = snewn(N_PREF_ITEMS+1, config_item);
949
950 ret[PREF_DRAW_FAINT_LINES].name = "Draw excluded grid lines faintly";
951 ret[PREF_DRAW_FAINT_LINES].kw = "draw-faint-lines";
952 ret[PREF_DRAW_FAINT_LINES].type = C_BOOLEAN;
953 ret[PREF_DRAW_FAINT_LINES].u.boolean.bval = ui->draw_faint_lines;
954
955 ret[PREF_AUTO_FOLLOW].name = "Auto-follow unique paths of edges";
956 ret[PREF_AUTO_FOLLOW].kw = "auto-follow";
957 ret[PREF_AUTO_FOLLOW].type = C_CHOICES;
958 ret[PREF_AUTO_FOLLOW].u.choices.choicenames =
959 ":No:Based on grid only:Based on grid and game state";
960 ret[PREF_AUTO_FOLLOW].u.choices.choicekws = ":off:fixed:adaptive";
961 ret[PREF_AUTO_FOLLOW].u.choices.selected = ui->autofollow;
962
963 ret[N_PREF_ITEMS].name = NULL;
964 ret[N_PREF_ITEMS].type = C_END;
965
966 return ret;
967}
968
969static void set_prefs(game_ui *ui, const config_item *cfg)
970{
971 ui->draw_faint_lines = cfg[PREF_DRAW_FAINT_LINES].u.boolean.bval;
972 ui->autofollow = cfg[PREF_AUTO_FOLLOW].u.choices.selected;
973}
974
975static void game_changed_state(game_ui *ui, const game_state *oldstate,
976 const game_state *newstate)
977{
978}
979
980static void game_compute_size(const game_params *params, int tilesize,
981 const game_ui *ui, int *x, int *y)
982{
983 int grid_width, grid_height, rendered_width, rendered_height;
984 int g_tilesize;
985
986 grid_compute_size(grid_types[params->type], params->w, params->h,
987 &g_tilesize, &grid_width, &grid_height);
988
989 /* multiply first to minimise rounding error on integer division */
990 rendered_width = grid_width * tilesize / g_tilesize;
991 rendered_height = grid_height * tilesize / g_tilesize;
992 *x = rendered_width + 2 * BORDER(tilesize) + 1;
993 *y = rendered_height + 2 * BORDER(tilesize) + 1;
994}
995
996static void game_set_size(drawing *dr, game_drawstate *ds,
997 const game_params *params, int tilesize)
998{
999 ds->tilesize = tilesize;
1000}
1001
1002static float *game_colours(frontend *fe, int *ncolours)
1003{
1004 float *ret = snewn(3 * NCOLOURS, float);
1005
1006 frontend_default_colour(fe, &ret[COL_BACKGROUND * 3]);
1007
1008 ret[COL_FOREGROUND * 3 + 0] = 0.0F;
1009 ret[COL_FOREGROUND * 3 + 1] = 0.0F;
1010 ret[COL_FOREGROUND * 3 + 2] = 0.0F;
1011
1012 /*
1013 * We want COL_LINEUNKNOWN to be a yellow which is a bit darker
1014 * than the background. (I previously set it to 0.8,0.8,0, but
1015 * found that this went badly with the 0.8,0.8,0.8 favoured as a
1016 * background by the Java frontend.)
1017 */
1018 ret[COL_LINEUNKNOWN * 3 + 0] = ret[COL_BACKGROUND * 3 + 0] * 0.9F;
1019 ret[COL_LINEUNKNOWN * 3 + 1] = ret[COL_BACKGROUND * 3 + 1] * 0.9F;
1020 ret[COL_LINEUNKNOWN * 3 + 2] = 0.0F;
1021
1022 ret[COL_HIGHLIGHT * 3 + 0] = 1.0F;
1023 ret[COL_HIGHLIGHT * 3 + 1] = 1.0F;
1024 ret[COL_HIGHLIGHT * 3 + 2] = 1.0F;
1025
1026 ret[COL_MISTAKE * 3 + 0] = 1.0F;
1027 ret[COL_MISTAKE * 3 + 1] = 0.0F;
1028 ret[COL_MISTAKE * 3 + 2] = 0.0F;
1029
1030 ret[COL_SATISFIED * 3 + 0] = 0.0F;
1031 ret[COL_SATISFIED * 3 + 1] = 0.0F;
1032 ret[COL_SATISFIED * 3 + 2] = 0.0F;
1033
1034 /* We want the faint lines to be a bit darker than the background.
1035 * Except if the background is pretty dark already; then it ought to be a
1036 * bit lighter. Oy vey.
1037 */
1038 ret[COL_FAINT * 3 + 0] = ret[COL_BACKGROUND * 3 + 0] * 0.9F;
1039 ret[COL_FAINT * 3 + 1] = ret[COL_BACKGROUND * 3 + 1] * 0.9F;
1040 ret[COL_FAINT * 3 + 2] = ret[COL_BACKGROUND * 3 + 2] * 0.9F;
1041
1042 *ncolours = NCOLOURS;
1043 return ret;
1044}
1045
1046static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
1047{
1048 struct game_drawstate *ds = snew(struct game_drawstate);
1049 int num_faces = state->game_grid->num_faces;
1050 int num_edges = state->game_grid->num_edges;
1051 int i;
1052
1053 ds->tilesize = 0;
1054 ds->started = false;
1055 ds->lines = snewn(num_edges, char);
1056 ds->clue_error = snewn(num_faces, bool);
1057 ds->clue_satisfied = snewn(num_faces, bool);
1058 ds->textx = snewn(num_faces, int);
1059 ds->texty = snewn(num_faces, int);
1060 ds->flashing = false;
1061
1062 memset(ds->lines, LINE_UNKNOWN, num_edges);
1063 memset(ds->clue_error, 0, num_faces * sizeof(bool));
1064 memset(ds->clue_satisfied, 0, num_faces * sizeof(bool));
1065 for (i = 0; i < num_faces; i++)
1066 ds->textx[i] = ds->texty[i] = -1;
1067
1068 return ds;
1069}
1070
1071static void game_free_drawstate(drawing *dr, game_drawstate *ds)
1072{
1073 sfree(ds->textx);
1074 sfree(ds->texty);
1075 sfree(ds->clue_error);
1076 sfree(ds->clue_satisfied);
1077 sfree(ds->lines);
1078 sfree(ds);
1079}
1080
1081static float game_anim_length(const game_state *oldstate,
1082 const game_state *newstate, int dir, game_ui *ui)
1083{
1084 return 0.0F;
1085}
1086
1087static bool game_can_format_as_text_now(const game_params *params)
1088{
1089 if (params->type != 0)
1090 return false;
1091 return true;
1092}
1093
1094static char *game_text_format(const game_state *state)
1095{
1096 int w, h, W, H;
1097 int x, y, i;
1098 int cell_size;
1099 char *ret;
1100 grid *g = state->game_grid;
1101 grid_face *f;
1102
1103 assert(state->grid_type == 0);
1104
1105 /* Work out the basic size unit */
1106 f = g->faces[0]; /* first face */
1107 assert(f->order == 4);
1108 /* The dots are ordered clockwise, so the two opposite
1109 * corners are guaranteed to span the square */
1110 cell_size = abs(f->dots[0]->x - f->dots[2]->x);
1111
1112 w = (g->highest_x - g->lowest_x) / cell_size;
1113 h = (g->highest_y - g->lowest_y) / cell_size;
1114
1115 /* Create a blank "canvas" to "draw" on */
1116 W = 2 * w + 2;
1117 H = 2 * h + 1;
1118 ret = snewn(W * H + 1, char);
1119 for (y = 0; y < H; y++) {
1120 for (x = 0; x < W-1; x++) {
1121 ret[y*W + x] = ' ';
1122 }
1123 ret[y*W + W-1] = '\n';
1124 }
1125 ret[H*W] = '\0';
1126
1127 /* Fill in edge info */
1128 for (i = 0; i < g->num_edges; i++) {
1129 grid_edge *e = g->edges[i];
1130 /* Cell coordinates, from (0,0) to (w-1,h-1) */
1131 int x1 = (e->dot1->x - g->lowest_x) / cell_size;
1132 int x2 = (e->dot2->x - g->lowest_x) / cell_size;
1133 int y1 = (e->dot1->y - g->lowest_y) / cell_size;
1134 int y2 = (e->dot2->y - g->lowest_y) / cell_size;
1135 /* Midpoint, in canvas coordinates (canvas coordinates are just twice
1136 * cell coordinates) */
1137 x = x1 + x2;
1138 y = y1 + y2;
1139 switch (state->lines[i]) {
1140 case LINE_YES:
1141 ret[y*W + x] = (y1 == y2) ? '-' : '|';
1142 break;
1143 case LINE_NO:
1144 ret[y*W + x] = 'x';
1145 break;
1146 case LINE_UNKNOWN:
1147 break; /* already a space */
1148 default:
1149 assert(!"Illegal line state");
1150 }
1151 }
1152
1153 /* Fill in clues */
1154 for (i = 0; i < g->num_faces; i++) {
1155 int x1, x2, y1, y2;
1156
1157 f = g->faces[i];
1158 assert(f->order == 4);
1159 /* Cell coordinates, from (0,0) to (w-1,h-1) */
1160 x1 = (f->dots[0]->x - g->lowest_x) / cell_size;
1161 x2 = (f->dots[2]->x - g->lowest_x) / cell_size;
1162 y1 = (f->dots[0]->y - g->lowest_y) / cell_size;
1163 y2 = (f->dots[2]->y - g->lowest_y) / cell_size;
1164 /* Midpoint, in canvas coordinates */
1165 x = x1 + x2;
1166 y = y1 + y2;
1167 ret[y*W + x] = CLUE2CHAR(state->clues[i]);
1168 }
1169 return ret;
1170}
1171
1172/* ----------------------------------------------------------------------
1173 * Debug code
1174 */
1175
1176#ifdef DEBUG_CACHES
1177static void check_caches(const solver_state* sstate)
1178{
1179 int i;
1180 const game_state *state = sstate->state;
1181 const grid *g = state->game_grid;
1182
1183 for (i = 0; i < g->num_dots; i++) {
1184 assert(dot_order(state, i, LINE_YES) == sstate->dot_yes_count[i]);
1185 assert(dot_order(state, i, LINE_NO) == sstate->dot_no_count[i]);
1186 }
1187
1188 for (i = 0; i < g->num_faces; i++) {
1189 assert(face_order(state, i, LINE_YES) == sstate->face_yes_count[i]);
1190 assert(face_order(state, i, LINE_NO) == sstate->face_no_count[i]);
1191 }
1192}
1193
1194#if 0
1195#define check_caches(s) \
1196 do { \
1197 fprintf(stderr, "check_caches at line %d\n", __LINE__); \
1198 check_caches(s); \
1199 } while (0)
1200#endif
1201#endif /* DEBUG_CACHES */
1202
1203/* ----------------------------------------------------------------------
1204 * Solver utility functions
1205 */
1206
1207/* Sets the line (with index i) to the new state 'line_new', and updates
1208 * the cached counts of any affected faces and dots.
1209 * Returns true if this actually changed the line's state. */
1210static bool solver_set_line(solver_state *sstate, int i,
1211 enum line_state line_new
1212#ifdef SHOW_WORKING
1213 , const char *reason
1214#endif
1215 )
1216{
1217 game_state *state = sstate->state;
1218 grid *g;
1219 grid_edge *e;
1220
1221 assert(line_new != LINE_UNKNOWN);
1222
1223 check_caches(sstate);
1224
1225 if (state->lines[i] == line_new) {
1226 return false; /* nothing changed */
1227 }
1228 state->lines[i] = line_new;
1229
1230#ifdef SHOW_WORKING
1231 fprintf(stderr, "solver: set line [%d] to %s (%s)\n",
1232 i, line_new == LINE_YES ? "YES" : "NO",
1233 reason);
1234#endif
1235
1236 g = state->game_grid;
1237 e = g->edges[i];
1238
1239 /* Update the cache for both dots and both faces affected by this. */
1240 if (line_new == LINE_YES) {
1241 sstate->dot_yes_count[e->dot1->index]++;
1242 sstate->dot_yes_count[e->dot2->index]++;
1243 if (e->face1) {
1244 sstate->face_yes_count[e->face1->index]++;
1245 }
1246 if (e->face2) {
1247 sstate->face_yes_count[e->face2->index]++;
1248 }
1249 } else {
1250 sstate->dot_no_count[e->dot1->index]++;
1251 sstate->dot_no_count[e->dot2->index]++;
1252 if (e->face1) {
1253 sstate->face_no_count[e->face1->index]++;
1254 }
1255 if (e->face2) {
1256 sstate->face_no_count[e->face2->index]++;
1257 }
1258 }
1259
1260 check_caches(sstate);
1261 return true;
1262}
1263
1264#ifdef SHOW_WORKING
1265#define solver_set_line(a, b, c) \
1266 solver_set_line(a, b, c, __FUNCTION__)
1267#endif
1268
1269/*
1270 * Merge two dots due to the existence of an edge between them.
1271 * Updates the dsf tracking equivalence classes, and keeps track of
1272 * the length of path each dot is currently a part of.
1273 * Returns true if the dots were already linked, ie if they are part of a
1274 * closed loop, and false otherwise.
1275 */
1276static bool merge_dots(solver_state *sstate, int edge_index)
1277{
1278 int i, j, len;
1279 grid *g = sstate->state->game_grid;
1280 grid_edge *e = g->edges[edge_index];
1281
1282 i = e->dot1->index;
1283 j = e->dot2->index;
1284
1285 i = dsf_canonify(sstate->dotdsf, i);
1286 j = dsf_canonify(sstate->dotdsf, j);
1287
1288 if (i == j) {
1289 return true;
1290 } else {
1291 len = sstate->looplen[i] + sstate->looplen[j];
1292 dsf_merge(sstate->dotdsf, i, j);
1293 i = dsf_canonify(sstate->dotdsf, i);
1294 sstate->looplen[i] = len;
1295 return false;
1296 }
1297}
1298
1299/* Merge two lines because the solver has deduced that they must be either
1300 * identical or opposite. Returns true if this is new information, otherwise
1301 * false. */
1302static bool merge_lines(solver_state *sstate, int i, int j, bool inverse
1303#ifdef SHOW_WORKING
1304 , const char *reason
1305#endif
1306 )
1307{
1308 bool inv_tmp;
1309
1310 assert(i < sstate->state->game_grid->num_edges);
1311 assert(j < sstate->state->game_grid->num_edges);
1312
1313 i = dsf_canonify_flip(sstate->linedsf, i, &inv_tmp);
1314 inverse ^= inv_tmp;
1315 j = dsf_canonify_flip(sstate->linedsf, j, &inv_tmp);
1316 inverse ^= inv_tmp;
1317
1318 dsf_merge_flip(sstate->linedsf, i, j, inverse);
1319
1320#ifdef SHOW_WORKING
1321 if (i != j) {
1322 fprintf(stderr, "%s [%d] [%d] %s(%s)\n",
1323 __FUNCTION__, i, j,
1324 inverse ? "inverse " : "", reason);
1325 }
1326#endif
1327 return (i != j);
1328}
1329
1330#ifdef SHOW_WORKING
1331#define merge_lines(a, b, c, d) \
1332 merge_lines(a, b, c, d, __FUNCTION__)
1333#endif
1334
1335/* Count the number of lines of a particular type currently going into the
1336 * given dot. */
1337static int dot_order(const game_state* state, int dot, char line_type)
1338{
1339 int n = 0;
1340 grid *g = state->game_grid;
1341 grid_dot *d = g->dots[dot];
1342 int i;
1343
1344 for (i = 0; i < d->order; i++) {
1345 grid_edge *e = d->edges[i];
1346 if (state->lines[e->index] == line_type)
1347 ++n;
1348 }
1349 return n;
1350}
1351
1352/* Count the number of lines of a particular type currently surrounding the
1353 * given face */
1354static int face_order(const game_state* state, int face, char line_type)
1355{
1356 int n = 0;
1357 grid *g = state->game_grid;
1358 grid_face *f = g->faces[face];
1359 int i;
1360
1361 for (i = 0; i < f->order; i++) {
1362 grid_edge *e = f->edges[i];
1363 if (state->lines[e->index] == line_type)
1364 ++n;
1365 }
1366 return n;
1367}
1368
1369/* Set all lines bordering a dot of type old_type to type new_type
1370 * Return value tells caller whether this function actually did anything */
1371static bool dot_setall(solver_state *sstate, int dot,
1372 char old_type, char new_type)
1373{
1374 bool retval = false, r;
1375 game_state *state = sstate->state;
1376 grid *g;
1377 grid_dot *d;
1378 int i;
1379
1380 if (old_type == new_type)
1381 return false;
1382
1383 g = state->game_grid;
1384 d = g->dots[dot];
1385
1386 for (i = 0; i < d->order; i++) {
1387 int line_index = d->edges[i]->index;
1388 if (state->lines[line_index] == old_type) {
1389 r = solver_set_line(sstate, line_index, new_type);
1390 assert(r);
1391 retval = true;
1392 }
1393 }
1394 return retval;
1395}
1396
1397/* Set all lines bordering a face of type old_type to type new_type */
1398static bool face_setall(solver_state *sstate, int face,
1399 char old_type, char new_type)
1400{
1401 bool retval = false, r;
1402 game_state *state = sstate->state;
1403 grid *g;
1404 grid_face *f;
1405 int i;
1406
1407 if (old_type == new_type)
1408 return false;
1409
1410 g = state->game_grid;
1411 f = g->faces[face];
1412
1413 for (i = 0; i < f->order; i++) {
1414 int line_index = f->edges[i]->index;
1415 if (state->lines[line_index] == old_type) {
1416 r = solver_set_line(sstate, line_index, new_type);
1417 assert(r);
1418 retval = true;
1419 }
1420 }
1421 return retval;
1422}
1423
1424/* ----------------------------------------------------------------------
1425 * Loop generation and clue removal
1426 */
1427
1428static void add_full_clues(game_state *state, random_state *rs)
1429{
1430 signed char *clues = state->clues;
1431 grid *g = state->game_grid;
1432 char *board = snewn(g->num_faces, char);
1433 int i;
1434
1435 generate_loop(g, board, rs, NULL, NULL);
1436
1437 /* Fill out all the clues by initialising to 0, then iterating over
1438 * all edges and incrementing each clue as we find edges that border
1439 * between BLACK/WHITE faces. While we're at it, we verify that the
1440 * algorithm does work, and there aren't any GREY faces still there. */
1441 memset(clues, 0, g->num_faces);
1442 for (i = 0; i < g->num_edges; i++) {
1443 grid_edge *e = g->edges[i];
1444 grid_face *f1 = e->face1;
1445 grid_face *f2 = e->face2;
1446 enum face_colour c1 = FACE_COLOUR(f1);
1447 enum face_colour c2 = FACE_COLOUR(f2);
1448 assert(c1 != FACE_GREY);
1449 assert(c2 != FACE_GREY);
1450 if (c1 != c2) {
1451 if (f1) clues[f1->index]++;
1452 if (f2) clues[f2->index]++;
1453 }
1454 }
1455 sfree(board);
1456}
1457
1458
1459static bool game_has_unique_soln(const game_state *state, int diff)
1460{
1461 bool ret;
1462 solver_state *sstate_new;
1463 solver_state *sstate = new_solver_state(state, diff);
1464
1465 sstate_new = solve_game_rec(sstate);
1466
1467 assert(sstate_new->solver_status != SOLVER_MISTAKE);
1468 ret = (sstate_new->solver_status == SOLVER_SOLVED);
1469
1470 free_solver_state(sstate_new);
1471 free_solver_state(sstate);
1472
1473 return ret;
1474}
1475
1476
1477/* Remove clues one at a time at random. */
1478static game_state *remove_clues(game_state *state, random_state *rs,
1479 int diff)
1480{
1481 int *face_list;
1482 int num_faces = state->game_grid->num_faces;
1483 game_state *ret = dup_game(state), *saved_ret;
1484 int n;
1485
1486 /* We need to remove some clues. We'll do this by forming a list of all
1487 * available clues, shuffling it, then going along one at a
1488 * time clearing each clue in turn for which doing so doesn't render the
1489 * board unsolvable. */
1490 face_list = snewn(num_faces, int);
1491 for (n = 0; n < num_faces; ++n) {
1492 face_list[n] = n;
1493 }
1494
1495 shuffle(face_list, num_faces, sizeof(int), rs);
1496
1497 for (n = 0; n < num_faces; ++n) {
1498 saved_ret = dup_game(ret);
1499 ret->clues[face_list[n]] = -1;
1500
1501 if (game_has_unique_soln(ret, diff)) {
1502 free_game(saved_ret);
1503 } else {
1504 free_game(ret);
1505 ret = saved_ret;
1506 }
1507 }
1508 sfree(face_list);
1509
1510 return ret;
1511}
1512
1513
1514static char *new_game_desc(const game_params *params, random_state *rs,
1515 char **aux, bool interactive)
1516{
1517 /* solution and description both use run-length encoding in obvious ways */
1518 char *retval, *game_desc, *grid_desc;
1519 grid *g;
1520 game_state *state = snew(game_state);
1521 game_state *state_new;
1522
1523 grid_desc = grid_new_desc(grid_types[params->type], params->w, params->h, rs);
1524 state->game_grid = g = loopy_generate_grid(params, grid_desc);
1525
1526 state->clues = snewn(g->num_faces, signed char);
1527 state->lines = snewn(g->num_edges, char);
1528 state->line_errors = snewn(g->num_edges, bool);
1529 state->exactly_one_loop = false;
1530
1531 state->grid_type = params->type;
1532
1533 newboard_please:
1534
1535 memset(state->lines, LINE_UNKNOWN, g->num_edges);
1536 memset(state->line_errors, 0, g->num_edges * sizeof(bool));
1537
1538 state->solved = false;
1539 state->cheated = false;
1540
1541 /* Get a new random solvable board with all its clues filled in. Yes, this
1542 * can loop for ever if the params are suitably unfavourable, but
1543 * preventing games smaller than 4x4 seems to stop this happening */
1544 do {
1545 add_full_clues(state, rs);
1546 } while (!game_has_unique_soln(state, params->diff));
1547
1548 state_new = remove_clues(state, rs, params->diff);
1549 free_game(state);
1550 state = state_new;
1551
1552
1553 if (params->diff > 0 && game_has_unique_soln(state, params->diff-1)) {
1554#ifdef SHOW_WORKING
1555 fprintf(stderr, "Rejecting board, it is too easy\n");
1556#endif
1557 goto newboard_please;
1558 }
1559
1560 game_desc = state_to_text(state);
1561
1562 free_game(state);
1563
1564 if (grid_desc) {
1565 retval = snewn(strlen(grid_desc) + 1 + strlen(game_desc) + 1, char);
1566 sprintf(retval, "%s%c%s", grid_desc, (int)GRID_DESC_SEP, game_desc);
1567 sfree(grid_desc);
1568 sfree(game_desc);
1569 } else {
1570 retval = game_desc;
1571 }
1572
1573 assert(!validate_desc(params, retval));
1574
1575 return retval;
1576}
1577
1578static game_state *new_game(midend *me, const game_params *params,
1579 const char *desc)
1580{
1581 int i;
1582 game_state *state = snew(game_state);
1583 int empties_to_make = 0;
1584 int n,n2;
1585 const char *dp;
1586 char *grid_desc;
1587 grid *g;
1588 int num_faces, num_edges;
1589
1590 grid_desc = extract_grid_desc(&desc);
1591 state->game_grid = g = loopy_generate_grid(params, grid_desc);
1592 if (grid_desc) sfree(grid_desc);
1593
1594 dp = desc;
1595
1596 num_faces = g->num_faces;
1597 num_edges = g->num_edges;
1598
1599 state->clues = snewn(num_faces, signed char);
1600 state->lines = snewn(num_edges, char);
1601 state->line_errors = snewn(num_edges, bool);
1602 state->exactly_one_loop = false;
1603
1604 state->solved = state->cheated = false;
1605
1606 state->grid_type = params->type;
1607
1608 for (i = 0; i < num_faces; i++) {
1609 if (empties_to_make) {
1610 empties_to_make--;
1611 state->clues[i] = -1;
1612 continue;
1613 }
1614
1615 assert(*dp);
1616 n = *dp - '0';
1617 n2 = *dp - 'A' + 10;
1618 if (n >= 0 && n < 10) {
1619 state->clues[i] = n;
1620 } else if (n2 >= 10 && n2 < 36) {
1621 state->clues[i] = n2;
1622 } else {
1623 n = *dp - 'a' + 1;
1624 assert(n > 0);
1625 state->clues[i] = -1;
1626 empties_to_make = n - 1;
1627 }
1628 ++dp;
1629 }
1630
1631 memset(state->lines, LINE_UNKNOWN, num_edges);
1632 memset(state->line_errors, 0, num_edges * sizeof(bool));
1633 return state;
1634}
1635
1636/* Calculates the line_errors data, and checks if the current state is a
1637 * solution */
1638static bool check_completion(game_state *state)
1639{
1640 grid *g = state->game_grid;
1641 int i;
1642 bool ret;
1643 DSF *dsf;
1644 int *component_state;
1645 int nsilly, nloop, npath, largest_comp, largest_size, total_pathsize;
1646 enum { COMP_NONE, COMP_LOOP, COMP_PATH, COMP_SILLY, COMP_EMPTY };
1647
1648 memset(state->line_errors, 0, g->num_edges * sizeof(bool));
1649
1650 /*
1651 * Find loops in the grid, and determine whether the puzzle is
1652 * solved.
1653 *
1654 * Loopy is a bit more complicated than most puzzles that care
1655 * about loop detection. In most of them, loops are simply
1656 * _forbidden_; so the obviously right way to do
1657 * error-highlighting during play is to light up a graph edge red
1658 * iff it is part of a loop, which is exactly what the centralised
1659 * findloop.c makes easy.
1660 *
1661 * But Loopy is unusual in that you're _supposed_ to be making a
1662 * loop - and yet _some_ loops are not the right loop. So we need
1663 * to be more discriminating, by identifying loops one by one and
1664 * then thinking about which ones to highlight, and so findloop.c
1665 * isn't quite the right tool for the job in this case.
1666 *
1667 * Worse still, consider situations in which the grid contains a
1668 * loop and also some non-loop edges: there are some cases like
1669 * this in which the user's intuitive expectation would be to
1670 * highlight the loop (if you're only about half way through the
1671 * puzzle and have accidentally made a little loop in some corner
1672 * of the grid), and others in which they'd be more likely to
1673 * expect you to highlight the non-loop edges (if you've just
1674 * closed off a whole loop that you thought was the entire
1675 * solution, but forgot some disconnected edges in a corner
1676 * somewhere). So while it's easy enough to check whether the
1677 * solution is _right_, highlighting the wrong parts is a tricky
1678 * problem for this puzzle!
1679 *
1680 * I'd quite like, in some situations, to identify the largest
1681 * loop among the player's YES edges, and then light up everything
1682 * other than that. But finding the longest cycle in a graph is an
1683 * NP-complete problem (because, in particular, it must return a
1684 * Hamilton cycle if one exists).
1685 *
1686 * However, I think we can make the problem tractable by
1687 * exercising the Puzzles principle that it isn't absolutely
1688 * necessary to highlight _all_ errors: the key point is that by
1689 * the time the user has filled in the whole grid, they should
1690 * either have seen a completion flash, or have _some_ error
1691 * highlight showing them why the solution isn't right. So in
1692 * principle it would be *just about* good enough to highlight
1693 * just one error in the whole grid, if there was really no better
1694 * way. But we'd like to highlight as many errors as possible.
1695 *
1696 * In this case, I think the simple approach is to make use of the
1697 * fact that no vertex may have degree > 2, and that's really
1698 * simple to detect. So the plan goes like this:
1699 *
1700 * - Form the dsf of connected components of the graph vertices.
1701 *
1702 * - Highlight an error at any vertex with degree > 2. (It so
1703 * happens that we do this by lighting up all the edges
1704 * incident to that vertex, but that's an output detail.)
1705 *
1706 * - Any component that contains such a vertex is now excluded
1707 * from further consideration, because it already has a
1708 * highlight.
1709 *
1710 * - The remaining components have no vertex with degree > 2, and
1711 * hence they all consist of either a simple loop, or a simple
1712 * path with two endpoints.
1713 *
1714 * - For these purposes, group together all the paths and imagine
1715 * them to be a single component (because in most normal
1716 * situations the player will gradually build up the solution
1717 * _not_ all in one connected segment, but as lots of separate
1718 * little path pieces that gradually connect to each other).
1719 *
1720 * - After doing that, if there is exactly one (sensible)
1721 * component - be it a collection of paths or a loop - then
1722 * highlight no further edge errors. (The former case is normal
1723 * during play, and the latter is a potentially solved puzzle.)
1724 *
1725 * - Otherwise, find the largest of the sensible components,
1726 * leave that one unhighlighted, and light the rest up in red.
1727 */
1728
1729 dsf = dsf_new(g->num_dots);
1730
1731 /* Build the dsf. */
1732 for (i = 0; i < g->num_edges; i++) {
1733 if (state->lines[i] == LINE_YES) {
1734 grid_edge *e = g->edges[i];
1735 int d1 = e->dot1->index, d2 = e->dot2->index;
1736 dsf_merge(dsf, d1, d2);
1737 }
1738 }
1739
1740 /* Initialise a state variable for each connected component. */
1741 component_state = snewn(g->num_dots, int);
1742 for (i = 0; i < g->num_dots; i++) {
1743 if (dsf_canonify(dsf, i) == i)
1744 component_state[i] = COMP_LOOP;
1745 else
1746 component_state[i] = COMP_NONE;
1747 }
1748
1749 /* Check for dots with degree > 3. Here we also spot dots of
1750 * degree 1 in which the user has marked all the non-edges as
1751 * LINE_NO, because those are also clear vertex-level errors, so
1752 * we give them the same treatment of excluding their connected
1753 * component from the subsequent loop analysis. */
1754 for (i = 0; i < g->num_dots; i++) {
1755 int comp = dsf_canonify(dsf, i);
1756 int yes = dot_order(state, i, LINE_YES);
1757 int unknown = dot_order(state, i, LINE_UNKNOWN);
1758 if ((yes == 1 && unknown == 0) || (yes >= 3)) {
1759 /* violation, so mark all YES edges as errors */
1760 grid_dot *d = g->dots[i];
1761 int j;
1762 for (j = 0; j < d->order; j++) {
1763 int e = d->edges[j]->index;
1764 if (state->lines[e] == LINE_YES)
1765 state->line_errors[e] = true;
1766 }
1767 /* And mark this component as not worthy of further
1768 * consideration. */
1769 component_state[comp] = COMP_SILLY;
1770
1771 } else if (yes == 0) {
1772 /* A completely isolated dot must also be excluded it from
1773 * the subsequent loop highlighting pass, but we tag it
1774 * with a different enum value to avoid it counting
1775 * towards the components that inhibit returning a win
1776 * status. */
1777 component_state[comp] = COMP_EMPTY;
1778 } else if (yes == 1) {
1779 /* A dot with degree 1 that didn't fall into the 'clearly
1780 * erroneous' case above indicates that this connected
1781 * component will be a path rather than a loop - unless
1782 * something worse elsewhere in the component has
1783 * classified it as silly. */
1784 if (component_state[comp] != COMP_SILLY)
1785 component_state[comp] = COMP_PATH;
1786 }
1787 }
1788
1789 /* Count up the components. Also, find the largest sensible
1790 * component. (Tie-breaking condition is derived from the order of
1791 * vertices in the grid data structure, which is fairly arbitrary
1792 * but at least stays stable throughout the game.) */
1793 nsilly = nloop = npath = 0;
1794 total_pathsize = 0;
1795 largest_comp = largest_size = -1;
1796 for (i = 0; i < g->num_dots; i++) {
1797 if (component_state[i] == COMP_SILLY) {
1798 nsilly++;
1799 } else if (component_state[i] == COMP_PATH) {
1800 total_pathsize += dsf_size(dsf, i);
1801 npath = 1;
1802 } else if (component_state[i] == COMP_LOOP) {
1803 int this_size;
1804
1805 nloop++;
1806
1807 if ((this_size = dsf_size(dsf, i)) > largest_size) {
1808 largest_comp = i;
1809 largest_size = this_size;
1810 }
1811 }
1812 }
1813 if (largest_size < total_pathsize) {
1814 largest_comp = -1; /* means the paths */
1815 largest_size = total_pathsize;
1816 }
1817
1818 if (nloop > 0 && nloop + npath > 1) {
1819 /*
1820 * If there are at least two sensible components including at
1821 * least one loop, highlight all edges in every sensible
1822 * component that is not the largest one.
1823 */
1824 for (i = 0; i < g->num_edges; i++) {
1825 if (state->lines[i] == LINE_YES) {
1826 grid_edge *e = g->edges[i];
1827 int d1 = e->dot1->index; /* either endpoint is good enough */
1828 int comp = dsf_canonify(dsf, d1);
1829 if ((component_state[comp] == COMP_PATH &&
1830 -1 != largest_comp) ||
1831 (component_state[comp] == COMP_LOOP &&
1832 comp != largest_comp))
1833 state->line_errors[i] = true;
1834 }
1835 }
1836 }
1837
1838 if (nloop == 1 && npath == 0 && nsilly == 0) {
1839 /*
1840 * If there is exactly one component and it is a loop, then
1841 * the puzzle is potentially complete, so check the clues.
1842 */
1843 ret = true;
1844
1845 for (i = 0; i < g->num_faces; i++) {
1846 int c = state->clues[i];
1847 if (c >= 0 && face_order(state, i, LINE_YES) != c) {
1848 ret = false;
1849 break;
1850 }
1851 }
1852
1853 /*
1854 * Also, whether or not the puzzle is actually complete, set
1855 * the flag that says this game_state has exactly one loop and
1856 * nothing else, which will be used to vary the semantics of
1857 * clue highlighting at display time.
1858 */
1859 state->exactly_one_loop = true;
1860 } else {
1861 ret = false;
1862 state->exactly_one_loop = false;
1863 }
1864
1865 sfree(component_state);
1866 dsf_free(dsf);
1867
1868 return ret;
1869}
1870
1871/* ----------------------------------------------------------------------
1872 * Solver logic
1873 *
1874 * Our solver modes operate as follows. Each mode also uses the modes above it.
1875 *
1876 * Easy Mode
1877 * Just implement the rules of the game.
1878 *
1879 * Normal and Tricky Modes
1880 * For each (adjacent) pair of lines through each dot we store a bit for
1881 * whether at least one of them is on and whether at most one is on. (If we
1882 * know both or neither is on that's already stored more directly.)
1883 *
1884 * Advanced Mode
1885 * Use flip dsf data structure to make equivalence classes of lines that are
1886 * known identical to or opposite to one another.
1887 */
1888
1889
1890/* DLines:
1891 * For general grids, we consider "dlines" to be pairs of lines joined
1892 * at a dot. The lines must be adjacent around the dot, so we can think of
1893 * a dline as being a dot+face combination. Or, a dot+edge combination where
1894 * the second edge is taken to be the next clockwise edge from the dot.
1895 * Original loopy code didn't have this extra restriction of the lines being
1896 * adjacent. From my tests with square grids, this extra restriction seems to
1897 * take little, if anything, away from the quality of the puzzles.
1898 * A dline can be uniquely identified by an edge/dot combination, given that
1899 * a dline-pair always goes clockwise around its common dot. The edge/dot
1900 * combination can be represented by an edge/bool combination - if bool is
1901 * true, use edge->dot1 else use edge->dot2. So the total number of dlines is
1902 * exactly twice the number of edges in the grid - although the dlines
1903 * spanning the infinite face are not all that useful to the solver.
1904 * Note that, by convention, a dline goes clockwise around its common dot,
1905 * which means the dline goes anti-clockwise around its common face.
1906 */
1907
1908/* Helper functions for obtaining an index into an array of dlines, given
1909 * various information. We assume the grid layout conventions about how
1910 * the various lists are interleaved - see grid_make_consistent() for
1911 * details. */
1912
1913/* i points to the first edge of the dline pair, reading clockwise around
1914 * the dot. */
1915static int dline_index_from_dot(grid *g, grid_dot *d, int i)
1916{
1917 grid_edge *e = d->edges[i];
1918 int ret;
1919#ifdef DEBUG_DLINES
1920 grid_edge *e2;
1921 int i2 = i+1;
1922 if (i2 == d->order) i2 = 0;
1923 e2 = d->edges[i2];
1924#endif
1925 ret = 2 * (e->index) + ((e->dot1 == d) ? 1 : 0);
1926#ifdef DEBUG_DLINES
1927 printf("dline_index_from_dot: d=%d,i=%d, edges [%d,%d] - %d\n",
1928 (int)(d->index), i, (int)(e->index), (int)(e2 ->index), ret);
1929#endif
1930 return ret;
1931}
1932/* i points to the second edge of the dline pair, reading clockwise around
1933 * the face. That is, the edges of the dline, starting at edge{i}, read
1934 * anti-clockwise around the face. By layout conventions, the common dot
1935 * of the dline will be f->dots[i] */
1936static int dline_index_from_face(grid *g, grid_face *f, int i)
1937{
1938 grid_edge *e = f->edges[i];
1939 grid_dot *d = f->dots[i];
1940 int ret;
1941#ifdef DEBUG_DLINES
1942 grid_edge *e2;
1943 int i2 = i - 1;
1944 if (i2 < 0) i2 += f->order;
1945 e2 = f->edges[i2];
1946#endif
1947 ret = 2 * (e->index) + ((e->dot1 == d) ? 1 : 0);
1948#ifdef DEBUG_DLINES
1949 printf("dline_index_from_face: f=%d,i=%d, edges [%d,%d] - %d\n",
1950 (int)(f->index), i, (int)(e->index), (int)(e2->index), ret);
1951#endif
1952 return ret;
1953}
1954static bool is_atleastone(const char *dline_array, int index)
1955{
1956 return BIT_SET(dline_array[index], 0);
1957}
1958static bool set_atleastone(char *dline_array, int index)
1959{
1960 return SET_BIT(dline_array[index], 0);
1961}
1962static bool is_atmostone(const char *dline_array, int index)
1963{
1964 return BIT_SET(dline_array[index], 1);
1965}
1966static bool set_atmostone(char *dline_array, int index)
1967{
1968 return SET_BIT(dline_array[index], 1);
1969}
1970
1971static void array_setall(char *array, char from, char to, int len)
1972{
1973 char *p = array, *p_old = p;
1974 int len_remaining = len;
1975
1976 while ((p = memchr(p, from, len_remaining))) {
1977 *p = to;
1978 len_remaining -= p - p_old;
1979 p_old = p;
1980 }
1981}
1982
1983/* Helper, called when doing dline dot deductions, in the case where we
1984 * have 4 UNKNOWNs, and two of them (adjacent) have *exactly* one YES between
1985 * them (because of dline atmostone/atleastone).
1986 * On entry, edge points to the first of these two UNKNOWNs. This function
1987 * will find the opposite UNKNOWNS (if they are adjacent to one another)
1988 * and set their corresponding dline to atleastone. (Setting atmostone
1989 * already happens in earlier dline deductions) */
1990static bool dline_set_opp_atleastone(solver_state *sstate,
1991 grid_dot *d, int edge)
1992{
1993 game_state *state = sstate->state;
1994 grid *g = state->game_grid;
1995 int N = d->order;
1996 int opp, opp2;
1997 for (opp = 0; opp < N; opp++) {
1998 int opp_dline_index;
1999 if (opp == edge || opp == edge+1 || opp == edge-1)
2000 continue;
2001 if (opp == 0 && edge == N-1)
2002 continue;
2003 if (opp == N-1 && edge == 0)
2004 continue;
2005 opp2 = opp + 1;
2006 if (opp2 == N) opp2 = 0;
2007 /* Check if opp, opp2 point to LINE_UNKNOWNs */
2008 if (state->lines[d->edges[opp]->index] != LINE_UNKNOWN)
2009 continue;
2010 if (state->lines[d->edges[opp2]->index] != LINE_UNKNOWN)
2011 continue;
2012 /* Found opposite UNKNOWNS and they're next to each other */
2013 opp_dline_index = dline_index_from_dot(g, d, opp);
2014 return set_atleastone(sstate->dlines, opp_dline_index);
2015 }
2016 return false;
2017}
2018
2019
2020/* Set pairs of lines around this face which are known to be identical, to
2021 * the given line_state */
2022static bool face_setall_identical(solver_state *sstate, int face_index,
2023 enum line_state line_new)
2024{
2025 /* can[dir] contains the canonical line associated with the line in
2026 * direction dir from the square in question. Similarly inv[dir] is
2027 * whether or not the line in question is inverse to its canonical
2028 * element. */
2029 bool retval = false;
2030 game_state *state = sstate->state;
2031 grid *g = state->game_grid;
2032 grid_face *f = g->faces[face_index];
2033 int N = f->order;
2034 int i, j;
2035 int can1, can2;
2036 bool inv1, inv2;
2037
2038 for (i = 0; i < N; i++) {
2039 int line1_index = f->edges[i]->index;
2040 if (state->lines[line1_index] != LINE_UNKNOWN)
2041 continue;
2042 for (j = i + 1; j < N; j++) {
2043 int line2_index = f->edges[j]->index;
2044 if (state->lines[line2_index] != LINE_UNKNOWN)
2045 continue;
2046
2047 /* Found two UNKNOWNS */
2048 can1 = dsf_canonify_flip(sstate->linedsf, line1_index, &inv1);
2049 can2 = dsf_canonify_flip(sstate->linedsf, line2_index, &inv2);
2050 if (can1 == can2 && inv1 == inv2) {
2051 solver_set_line(sstate, line1_index, line_new);
2052 solver_set_line(sstate, line2_index, line_new);
2053 }
2054 }
2055 }
2056 return retval;
2057}
2058
2059/* Given a dot or face, and a count of LINE_UNKNOWNs, find them and
2060 * return the edge indices into e. */
2061static void find_unknowns(game_state *state,
2062 grid_edge **edge_list, /* Edge list to search (from a face or a dot) */
2063 int expected_count, /* Number of UNKNOWNs (comes from solver's cache) */
2064 int *e /* Returned edge indices */)
2065{
2066 int c = 0;
2067 while (c < expected_count) {
2068 int line_index = (*edge_list)->index;
2069 if (state->lines[line_index] == LINE_UNKNOWN) {
2070 e[c] = line_index;
2071 c++;
2072 }
2073 ++edge_list;
2074 }
2075}
2076
2077/* If we have a list of edges, and we know whether the number of YESs should
2078 * be odd or even, and there are only a few UNKNOWNs, we can do some simple
2079 * linedsf deductions. This can be used for both face and dot deductions.
2080 * Returns the difficulty level of the next solver that should be used,
2081 * or DIFF_MAX if no progress was made. */
2082static int parity_deductions(solver_state *sstate,
2083 grid_edge **edge_list, /* Edge list (from a face or a dot) */
2084 int total_parity, /* Expected number of YESs modulo 2 (either 0 or 1) */
2085 int unknown_count)
2086{
2087 game_state *state = sstate->state;
2088 int diff = DIFF_MAX;
2089 DSF *linedsf = sstate->linedsf;
2090
2091 if (unknown_count == 2) {
2092 /* Lines are known alike/opposite, depending on inv. */
2093 int e[2];
2094 find_unknowns(state, edge_list, 2, e);
2095 if (merge_lines(sstate, e[0], e[1], total_parity))
2096 diff = min(diff, DIFF_HARD);
2097 } else if (unknown_count == 3) {
2098 int e[3];
2099 int can[3]; /* canonical edges */
2100 bool inv[3]; /* whether can[x] is inverse to e[x] */
2101 find_unknowns(state, edge_list, 3, e);
2102 can[0] = dsf_canonify_flip(linedsf, e[0], inv);
2103 can[1] = dsf_canonify_flip(linedsf, e[1], inv+1);
2104 can[2] = dsf_canonify_flip(linedsf, e[2], inv+2);
2105 if (can[0] == can[1]) {
2106 if (solver_set_line(sstate, e[2], (total_parity^inv[0]^inv[1]) ?
2107 LINE_YES : LINE_NO))
2108 diff = min(diff, DIFF_EASY);
2109 }
2110 if (can[0] == can[2]) {
2111 if (solver_set_line(sstate, e[1], (total_parity^inv[0]^inv[2]) ?
2112 LINE_YES : LINE_NO))
2113 diff = min(diff, DIFF_EASY);
2114 }
2115 if (can[1] == can[2]) {
2116 if (solver_set_line(sstate, e[0], (total_parity^inv[1]^inv[2]) ?
2117 LINE_YES : LINE_NO))
2118 diff = min(diff, DIFF_EASY);
2119 }
2120 } else if (unknown_count == 4) {
2121 int e[4];
2122 int can[4]; /* canonical edges */
2123 bool inv[4]; /* whether can[x] is inverse to e[x] */
2124 find_unknowns(state, edge_list, 4, e);
2125 can[0] = dsf_canonify_flip(linedsf, e[0], inv);
2126 can[1] = dsf_canonify_flip(linedsf, e[1], inv+1);
2127 can[2] = dsf_canonify_flip(linedsf, e[2], inv+2);
2128 can[3] = dsf_canonify_flip(linedsf, e[3], inv+3);
2129 if (can[0] == can[1]) {
2130 if (merge_lines(sstate, e[2], e[3], total_parity^inv[0]^inv[1]))
2131 diff = min(diff, DIFF_HARD);
2132 } else if (can[0] == can[2]) {
2133 if (merge_lines(sstate, e[1], e[3], total_parity^inv[0]^inv[2]))
2134 diff = min(diff, DIFF_HARD);
2135 } else if (can[0] == can[3]) {
2136 if (merge_lines(sstate, e[1], e[2], total_parity^inv[0]^inv[3]))
2137 diff = min(diff, DIFF_HARD);
2138 } else if (can[1] == can[2]) {
2139 if (merge_lines(sstate, e[0], e[3], total_parity^inv[1]^inv[2]))
2140 diff = min(diff, DIFF_HARD);
2141 } else if (can[1] == can[3]) {
2142 if (merge_lines(sstate, e[0], e[2], total_parity^inv[1]^inv[3]))
2143 diff = min(diff, DIFF_HARD);
2144 } else if (can[2] == can[3]) {
2145 if (merge_lines(sstate, e[0], e[1], total_parity^inv[2]^inv[3]))
2146 diff = min(diff, DIFF_HARD);
2147 }
2148 }
2149 return diff;
2150}
2151
2152
2153/*
2154 * These are the main solver functions.
2155 *
2156 * Their return values are diff values corresponding to the lowest mode solver
2157 * that would notice the work that they have done. For example if the normal
2158 * mode solver adds actual lines or crosses, it will return DIFF_EASY as the
2159 * easy mode solver might be able to make progress using that. It doesn't make
2160 * sense for one of them to return a diff value higher than that of the
2161 * function itself.
2162 *
2163 * Each function returns the lowest value it can, as early as possible, in
2164 * order to try and pass as much work as possible back to the lower level
2165 * solvers which progress more quickly.
2166 */
2167
2168/* PROPOSED NEW DESIGN:
2169 * We have a work queue consisting of 'events' notifying us that something has
2170 * happened that a particular solver mode might be interested in. For example
2171 * the hard mode solver might do something that helps the normal mode solver at
2172 * dot [x,y] in which case it will enqueue an event recording this fact. Then
2173 * we pull events off the work queue, and hand each in turn to the solver that
2174 * is interested in them. If a solver reports that it failed we pass the same
2175 * event on to progressively more advanced solvers and the loop detector. Once
2176 * we've exhausted an event, or it has helped us progress, we drop it and
2177 * continue to the next one. The events are sorted first in order of solver
2178 * complexity (easy first) then order of insertion (oldest first).
2179 * Once we run out of events we loop over each permitted solver in turn
2180 * (easiest first) until either a deduction is made (and an event therefore
2181 * emerges) or no further deductions can be made (in which case we've failed).
2182 *
2183 * QUESTIONS:
2184 * * How do we 'loop over' a solver when both dots and squares are concerned.
2185 * Answer: first all squares then all dots.
2186 */
2187
2188static int trivial_deductions(solver_state *sstate)
2189{
2190 int i, current_yes, current_no;
2191 game_state *state = sstate->state;
2192 grid *g = state->game_grid;
2193 int diff = DIFF_MAX;
2194
2195 /* Per-face deductions */
2196 for (i = 0; i < g->num_faces; i++) {
2197 grid_face *f = g->faces[i];
2198
2199 if (sstate->face_solved[i])
2200 continue;
2201
2202 current_yes = sstate->face_yes_count[i];
2203 current_no = sstate->face_no_count[i];
2204
2205 if (current_yes + current_no == f->order) {
2206 sstate->face_solved[i] = true;
2207 continue;
2208 }
2209
2210 if (state->clues[i] < 0)
2211 continue;
2212
2213 /*
2214 * This code checks whether the numeric clue on a face is so
2215 * large as to permit all its remaining LINE_UNKNOWNs to be
2216 * filled in as LINE_YES, or alternatively so small as to
2217 * permit them all to be filled in as LINE_NO.
2218 */
2219
2220 if (state->clues[i] < current_yes) {
2221 sstate->solver_status = SOLVER_MISTAKE;
2222 return DIFF_EASY;
2223 }
2224 if (state->clues[i] == current_yes) {
2225 if (face_setall(sstate, i, LINE_UNKNOWN, LINE_NO))
2226 diff = min(diff, DIFF_EASY);
2227 sstate->face_solved[i] = true;
2228 continue;
2229 }
2230
2231 if (f->order - state->clues[i] < current_no) {
2232 sstate->solver_status = SOLVER_MISTAKE;
2233 return DIFF_EASY;
2234 }
2235 if (f->order - state->clues[i] == current_no) {
2236 if (face_setall(sstate, i, LINE_UNKNOWN, LINE_YES))
2237 diff = min(diff, DIFF_EASY);
2238 sstate->face_solved[i] = true;
2239 continue;
2240 }
2241
2242 if (f->order - state->clues[i] == current_no + 1 &&
2243 f->order - current_yes - current_no > 2) {
2244 /*
2245 * One small refinement to the above: we also look for any
2246 * adjacent pair of LINE_UNKNOWNs around the face with
2247 * some LINE_YES incident on it from elsewhere. If we find
2248 * one, then we know that pair of LINE_UNKNOWNs can't
2249 * _both_ be LINE_YES, and hence that pushes us one line
2250 * closer to being able to determine all the rest.
2251 */
2252 int j, k, e1, e2, e, d;
2253
2254 for (j = 0; j < f->order; j++) {
2255 e1 = f->edges[j]->index;
2256 e2 = f->edges[j+1 < f->order ? j+1 : 0]->index;
2257
2258 if (g->edges[e1]->dot1 == g->edges[e2]->dot1 ||
2259 g->edges[e1]->dot1 == g->edges[e2]->dot2) {
2260 d = g->edges[e1]->dot1->index;
2261 } else {
2262 assert(g->edges[e1]->dot2 == g->edges[e2]->dot1 ||
2263 g->edges[e1]->dot2 == g->edges[e2]->dot2);
2264 d = g->edges[e1]->dot2->index;
2265 }
2266
2267 if (state->lines[e1] == LINE_UNKNOWN &&
2268 state->lines[e2] == LINE_UNKNOWN) {
2269 for (k = 0; k < g->dots[d]->order; k++) {
2270 int e = g->dots[d]->edges[k]->index;
2271 if (state->lines[e] == LINE_YES)
2272 goto found; /* multi-level break */
2273 }
2274 }
2275 }
2276 continue;
2277
2278 found:
2279 /*
2280 * If we get here, we've found such a pair of edges, and
2281 * they're e1 and e2.
2282 */
2283 for (j = 0; j < f->order; j++) {
2284 e = f->edges[j]->index;
2285 if (state->lines[e] == LINE_UNKNOWN && e != e1 && e != e2) {
2286 bool r = solver_set_line(sstate, e, LINE_YES);
2287 assert(r);
2288 diff = min(diff, DIFF_EASY);
2289 }
2290 }
2291 }
2292 }
2293
2294 check_caches(sstate);
2295
2296 /* Per-dot deductions */
2297 for (i = 0; i < g->num_dots; i++) {
2298 grid_dot *d = g->dots[i];
2299 int yes, no, unknown;
2300
2301 if (sstate->dot_solved[i])
2302 continue;
2303
2304 yes = sstate->dot_yes_count[i];
2305 no = sstate->dot_no_count[i];
2306 unknown = d->order - yes - no;
2307
2308 if (yes == 0) {
2309 if (unknown == 0) {
2310 sstate->dot_solved[i] = true;
2311 } else if (unknown == 1) {
2312 dot_setall(sstate, i, LINE_UNKNOWN, LINE_NO);
2313 diff = min(diff, DIFF_EASY);
2314 sstate->dot_solved[i] = true;
2315 }
2316 } else if (yes == 1) {
2317 if (unknown == 0) {
2318 sstate->solver_status = SOLVER_MISTAKE;
2319 return DIFF_EASY;
2320 } else if (unknown == 1) {
2321 dot_setall(sstate, i, LINE_UNKNOWN, LINE_YES);
2322 diff = min(diff, DIFF_EASY);
2323 }
2324 } else if (yes == 2) {
2325 if (unknown > 0) {
2326 dot_setall(sstate, i, LINE_UNKNOWN, LINE_NO);
2327 diff = min(diff, DIFF_EASY);
2328 }
2329 sstate->dot_solved[i] = true;
2330 } else {
2331 sstate->solver_status = SOLVER_MISTAKE;
2332 return DIFF_EASY;
2333 }
2334 }
2335
2336 check_caches(sstate);
2337
2338 return diff;
2339}
2340
2341static int dline_deductions(solver_state *sstate)
2342{
2343 game_state *state = sstate->state;
2344 grid *g = state->game_grid;
2345 char *dlines = sstate->dlines;
2346 int i;
2347 int diff = DIFF_MAX;
2348
2349 /* ------ Face deductions ------ */
2350
2351 /* Given a set of dline atmostone/atleastone constraints, need to figure
2352 * out if we can deduce any further info. For more general faces than
2353 * squares, this turns out to be a tricky problem.
2354 * The approach taken here is to define (per face) NxN matrices:
2355 * "maxs" and "mins".
2356 * The entries maxs(j,k) and mins(j,k) define the upper and lower limits
2357 * for the possible number of edges that are YES between positions j and k
2358 * going clockwise around the face. Can think of j and k as marking dots
2359 * around the face (recall the labelling scheme: edge0 joins dot0 to dot1,
2360 * edge1 joins dot1 to dot2 etc).
2361 * Trivially, mins(j,j) = maxs(j,j) = 0, and we don't even bother storing
2362 * these. mins(j,j+1) and maxs(j,j+1) are determined by whether edge{j}
2363 * is YES, NO or UNKNOWN. mins(j,j+2) and maxs(j,j+2) are related to
2364 * the dline atmostone/atleastone status for edges j and j+1.
2365 *
2366 * Then we calculate the remaining entries recursively. We definitely
2367 * know that
2368 * mins(j,k) >= { mins(j,u) + mins(u,k) } for any u between j and k.
2369 * This is because any valid placement of YESs between j and k must give
2370 * a valid placement between j and u, and also between u and k.
2371 * I believe it's sufficient to use just the two values of u:
2372 * j+1 and j+2. Seems to work well in practice - the bounds we compute
2373 * are rigorous, even if they might not be best-possible.
2374 *
2375 * Once we have maxs and mins calculated, we can make inferences about
2376 * each dline{j,j+1} by looking at the possible complementary edge-counts
2377 * mins(j+2,j) and maxs(j+2,j) and comparing these with the face clue.
2378 * As well as dlines, we can make similar inferences about single edges.
2379 * For example, consider a pentagon with clue 3, and we know at most one
2380 * of (edge0, edge1) is YES, and at most one of (edge2, edge3) is YES.
2381 * We could then deduce edge4 is YES, because maxs(0,4) would be 2, so
2382 * that final edge would have to be YES to make the count up to 3.
2383 */
2384
2385 /* Much quicker to allocate arrays on the stack than the heap, so
2386 * define the largest possible face size, and base our array allocations
2387 * on that. We check this with an assertion, in case someone decides to
2388 * make a grid which has larger faces than this. Note, this algorithm
2389 * could get quite expensive if there are many large faces. */
2390#define MAX_FACE_SIZE 14
2391
2392 for (i = 0; i < g->num_faces; i++) {
2393 int maxs[MAX_FACE_SIZE][MAX_FACE_SIZE];
2394 int mins[MAX_FACE_SIZE][MAX_FACE_SIZE];
2395 grid_face *f = g->faces[i];
2396 int N = f->order;
2397 int j,m;
2398 int clue = state->clues[i];
2399 assert(N <= MAX_FACE_SIZE);
2400 if (sstate->face_solved[i])
2401 continue;
2402 if (clue < 0) continue;
2403
2404 /* Calculate the (j,j+1) entries */
2405 for (j = 0; j < N; j++) {
2406 int edge_index = f->edges[j]->index;
2407 int dline_index;
2408 enum line_state line1 = state->lines[edge_index];
2409 enum line_state line2;
2410 int tmp;
2411 int k = j + 1;
2412 if (k >= N) k = 0;
2413 maxs[j][k] = (line1 == LINE_NO) ? 0 : 1;
2414 mins[j][k] = (line1 == LINE_YES) ? 1 : 0;
2415 /* Calculate the (j,j+2) entries */
2416 dline_index = dline_index_from_face(g, f, k);
2417 edge_index = f->edges[k]->index;
2418 line2 = state->lines[edge_index];
2419 k++;
2420 if (k >= N) k = 0;
2421
2422 /* max */
2423 tmp = 2;
2424 if (line1 == LINE_NO) tmp--;
2425 if (line2 == LINE_NO) tmp--;
2426 if (tmp == 2 && is_atmostone(dlines, dline_index))
2427 tmp = 1;
2428 maxs[j][k] = tmp;
2429
2430 /* min */
2431 tmp = 0;
2432 if (line1 == LINE_YES) tmp++;
2433 if (line2 == LINE_YES) tmp++;
2434 if (tmp == 0 && is_atleastone(dlines, dline_index))
2435 tmp = 1;
2436 mins[j][k] = tmp;
2437 }
2438
2439 /* Calculate the (j,j+m) entries for m between 3 and N-1 */
2440 for (m = 3; m < N; m++) {
2441 for (j = 0; j < N; j++) {
2442 int k = j + m;
2443 int u = j + 1;
2444 int v = j + 2;
2445 int tmp;
2446 if (k >= N) k -= N;
2447 if (u >= N) u -= N;
2448 if (v >= N) v -= N;
2449 maxs[j][k] = maxs[j][u] + maxs[u][k];
2450 mins[j][k] = mins[j][u] + mins[u][k];
2451 tmp = maxs[j][v] + maxs[v][k];
2452 maxs[j][k] = min(maxs[j][k], tmp);
2453 tmp = mins[j][v] + mins[v][k];
2454 mins[j][k] = max(mins[j][k], tmp);
2455 }
2456 }
2457
2458 /* See if we can make any deductions */
2459 for (j = 0; j < N; j++) {
2460 int k;
2461 grid_edge *e = f->edges[j];
2462 int line_index = e->index;
2463 int dline_index;
2464
2465 if (state->lines[line_index] != LINE_UNKNOWN)
2466 continue;
2467 k = j + 1;
2468 if (k >= N) k = 0;
2469
2470 /* minimum YESs in the complement of this edge */
2471 if (mins[k][j] > clue) {
2472 sstate->solver_status = SOLVER_MISTAKE;
2473 return DIFF_EASY;
2474 }
2475 if (mins[k][j] == clue) {
2476 /* setting this edge to YES would make at least
2477 * (clue+1) edges - contradiction */
2478 solver_set_line(sstate, line_index, LINE_NO);
2479 diff = min(diff, DIFF_EASY);
2480 }
2481 if (maxs[k][j] < clue - 1) {
2482 sstate->solver_status = SOLVER_MISTAKE;
2483 return DIFF_EASY;
2484 }
2485 if (maxs[k][j] == clue - 1) {
2486 /* Only way to satisfy the clue is to set edge{j} as YES */
2487 solver_set_line(sstate, line_index, LINE_YES);
2488 diff = min(diff, DIFF_EASY);
2489 }
2490
2491 /* More advanced deduction that allows propagation along diagonal
2492 * chains of faces connected by dots, for example, 3-2-...-2-3
2493 * in square grids. */
2494 if (sstate->diff >= DIFF_TRICKY) {
2495 /* Now see if we can make dline deduction for edges{j,j+1} */
2496 e = f->edges[k];
2497 if (state->lines[e->index] != LINE_UNKNOWN)
2498 /* Only worth doing this for an UNKNOWN,UNKNOWN pair.
2499 * Dlines where one of the edges is known, are handled in the
2500 * dot-deductions */
2501 continue;
2502
2503 dline_index = dline_index_from_face(g, f, k);
2504 k++;
2505 if (k >= N) k = 0;
2506
2507 /* minimum YESs in the complement of this dline */
2508 if (mins[k][j] > clue - 2) {
2509 /* Adding 2 YESs would break the clue */
2510 if (set_atmostone(dlines, dline_index))
2511 diff = min(diff, DIFF_NORMAL);
2512 }
2513 /* maximum YESs in the complement of this dline */
2514 if (maxs[k][j] < clue) {
2515 /* Adding 2 NOs would mean not enough YESs */
2516 if (set_atleastone(dlines, dline_index))
2517 diff = min(diff, DIFF_NORMAL);
2518 }
2519 }
2520 }
2521 }
2522
2523 if (diff < DIFF_NORMAL)
2524 return diff;
2525
2526 /* ------ Dot deductions ------ */
2527
2528 for (i = 0; i < g->num_dots; i++) {
2529 grid_dot *d = g->dots[i];
2530 int N = d->order;
2531 int yes, no, unknown;
2532 int j;
2533 if (sstate->dot_solved[i])
2534 continue;
2535 yes = sstate->dot_yes_count[i];
2536 no = sstate->dot_no_count[i];
2537 unknown = N - yes - no;
2538
2539 for (j = 0; j < N; j++) {
2540 int k;
2541 int dline_index;
2542 int line1_index, line2_index;
2543 enum line_state line1, line2;
2544 k = j + 1;
2545 if (k >= N) k = 0;
2546 dline_index = dline_index_from_dot(g, d, j);
2547 line1_index = d->edges[j]->index;
2548 line2_index = d->edges[k] ->index;
2549 line1 = state->lines[line1_index];
2550 line2 = state->lines[line2_index];
2551
2552 /* Infer dline state from line state */
2553 if (line1 == LINE_NO || line2 == LINE_NO) {
2554 if (set_atmostone(dlines, dline_index))
2555 diff = min(diff, DIFF_NORMAL);
2556 }
2557 if (line1 == LINE_YES || line2 == LINE_YES) {
2558 if (set_atleastone(dlines, dline_index))
2559 diff = min(diff, DIFF_NORMAL);
2560 }
2561 /* Infer line state from dline state */
2562 if (is_atmostone(dlines, dline_index)) {
2563 if (line1 == LINE_YES && line2 == LINE_UNKNOWN) {
2564 solver_set_line(sstate, line2_index, LINE_NO);
2565 diff = min(diff, DIFF_EASY);
2566 }
2567 if (line2 == LINE_YES && line1 == LINE_UNKNOWN) {
2568 solver_set_line(sstate, line1_index, LINE_NO);
2569 diff = min(diff, DIFF_EASY);
2570 }
2571 }
2572 if (is_atleastone(dlines, dline_index)) {
2573 if (line1 == LINE_NO && line2 == LINE_UNKNOWN) {
2574 solver_set_line(sstate, line2_index, LINE_YES);
2575 diff = min(diff, DIFF_EASY);
2576 }
2577 if (line2 == LINE_NO && line1 == LINE_UNKNOWN) {
2578 solver_set_line(sstate, line1_index, LINE_YES);
2579 diff = min(diff, DIFF_EASY);
2580 }
2581 }
2582 /* Deductions that depend on the numbers of lines.
2583 * Only bother if both lines are UNKNOWN, otherwise the
2584 * easy-mode solver (or deductions above) would have taken
2585 * care of it. */
2586 if (line1 != LINE_UNKNOWN || line2 != LINE_UNKNOWN)
2587 continue;
2588
2589 if (yes == 0 && unknown == 2) {
2590 /* Both these unknowns must be identical. If we know
2591 * atmostone or atleastone, we can make progress. */
2592 if (is_atmostone(dlines, dline_index)) {
2593 solver_set_line(sstate, line1_index, LINE_NO);
2594 solver_set_line(sstate, line2_index, LINE_NO);
2595 diff = min(diff, DIFF_EASY);
2596 }
2597 if (is_atleastone(dlines, dline_index)) {
2598 solver_set_line(sstate, line1_index, LINE_YES);
2599 solver_set_line(sstate, line2_index, LINE_YES);
2600 diff = min(diff, DIFF_EASY);
2601 }
2602 }
2603 if (yes == 1) {
2604 if (set_atmostone(dlines, dline_index))
2605 diff = min(diff, DIFF_NORMAL);
2606 if (unknown == 2) {
2607 if (set_atleastone(dlines, dline_index))
2608 diff = min(diff, DIFF_NORMAL);
2609 }
2610 }
2611
2612 /* More advanced deduction that allows propagation along diagonal
2613 * chains of faces connected by dots, for example: 3-2-...-2-3
2614 * in square grids. */
2615 if (sstate->diff >= DIFF_TRICKY) {
2616 /* If we have atleastone set for this dline, infer
2617 * atmostone for each "opposite" dline (that is, each
2618 * dline without edges in common with this one).
2619 * Again, this test is only worth doing if both these
2620 * lines are UNKNOWN. For if one of these lines were YES,
2621 * the (yes == 1) test above would kick in instead. */
2622 if (is_atleastone(dlines, dline_index)) {
2623 int opp;
2624 for (opp = 0; opp < N; opp++) {
2625 int opp_dline_index;
2626 if (opp == j || opp == j+1 || opp == j-1)
2627 continue;
2628 if (j == 0 && opp == N-1)
2629 continue;
2630 if (j == N-1 && opp == 0)
2631 continue;
2632 opp_dline_index = dline_index_from_dot(g, d, opp);
2633 if (set_atmostone(dlines, opp_dline_index))
2634 diff = min(diff, DIFF_NORMAL);
2635 }
2636 if (yes == 0 && is_atmostone(dlines, dline_index)) {
2637 /* This dline has *exactly* one YES and there are no
2638 * other YESs. This allows more deductions. */
2639 if (unknown == 3) {
2640 /* Third unknown must be YES */
2641 for (opp = 0; opp < N; opp++) {
2642 int opp_index;
2643 if (opp == j || opp == k)
2644 continue;
2645 opp_index = d->edges[opp]->index;
2646 if (state->lines[opp_index] == LINE_UNKNOWN) {
2647 solver_set_line(sstate, opp_index,
2648 LINE_YES);
2649 diff = min(diff, DIFF_EASY);
2650 }
2651 }
2652 } else if (unknown == 4) {
2653 /* Exactly one of opposite UNKNOWNS is YES. We've
2654 * already set atmostone, so set atleastone as
2655 * well.
2656 */
2657 if (dline_set_opp_atleastone(sstate, d, j))
2658 diff = min(diff, DIFF_NORMAL);
2659 }
2660 }
2661 }
2662 }
2663 }
2664 }
2665 return diff;
2666}
2667
2668static int linedsf_deductions(solver_state *sstate)
2669{
2670 game_state *state = sstate->state;
2671 grid *g = state->game_grid;
2672 char *dlines = sstate->dlines;
2673 int i;
2674 int diff = DIFF_MAX;
2675 int diff_tmp;
2676
2677 /* ------ Face deductions ------ */
2678
2679 /* A fully-general linedsf deduction seems overly complicated
2680 * (I suspect the problem is NP-complete, though in practice it might just
2681 * be doable because faces are limited in size).
2682 * For simplicity, we only consider *pairs* of LINE_UNKNOWNS that are
2683 * known to be identical. If setting them both to YES (or NO) would break
2684 * the clue, set them to NO (or YES). */
2685
2686 for (i = 0; i < g->num_faces; i++) {
2687 int N, yes, no, unknown;
2688 int clue;
2689
2690 if (sstate->face_solved[i])
2691 continue;
2692 clue = state->clues[i];
2693 if (clue < 0)
2694 continue;
2695
2696 N = g->faces[i]->order;
2697 yes = sstate->face_yes_count[i];
2698 if (yes + 1 == clue) {
2699 if (face_setall_identical(sstate, i, LINE_NO))
2700 diff = min(diff, DIFF_EASY);
2701 }
2702 no = sstate->face_no_count[i];
2703 if (no + 1 == N - clue) {
2704 if (face_setall_identical(sstate, i, LINE_YES))
2705 diff = min(diff, DIFF_EASY);
2706 }
2707
2708 /* Reload YES count, it might have changed */
2709 yes = sstate->face_yes_count[i];
2710 unknown = N - no - yes;
2711
2712 /* Deductions with small number of LINE_UNKNOWNs, based on overall
2713 * parity of lines. */
2714 diff_tmp = parity_deductions(sstate, g->faces[i]->edges,
2715 (clue - yes) % 2, unknown);
2716 diff = min(diff, diff_tmp);
2717 }
2718
2719 /* ------ Dot deductions ------ */
2720 for (i = 0; i < g->num_dots; i++) {
2721 grid_dot *d = g->dots[i];
2722 int N = d->order;
2723 int j;
2724 int yes, no, unknown;
2725 /* Go through dlines, and do any dline<->linedsf deductions wherever
2726 * we find two UNKNOWNS. */
2727 for (j = 0; j < N; j++) {
2728 int dline_index = dline_index_from_dot(g, d, j);
2729 int line1_index;
2730 int line2_index;
2731 int can1, can2;
2732 bool inv1, inv2;
2733 int j2;
2734 line1_index = d->edges[j]->index;
2735 if (state->lines[line1_index] != LINE_UNKNOWN)
2736 continue;
2737 j2 = j + 1;
2738 if (j2 == N) j2 = 0;
2739 line2_index = d->edges[j2]->index;
2740 if (state->lines[line2_index] != LINE_UNKNOWN)
2741 continue;
2742 /* Infer dline flags from linedsf */
2743 can1 = dsf_canonify_flip(sstate->linedsf, line1_index, &inv1);
2744 can2 = dsf_canonify_flip(sstate->linedsf, line2_index, &inv2);
2745 if (can1 == can2 && inv1 != inv2) {
2746 /* These are opposites, so set dline atmostone/atleastone */
2747 if (set_atmostone(dlines, dline_index))
2748 diff = min(diff, DIFF_NORMAL);
2749 if (set_atleastone(dlines, dline_index))
2750 diff = min(diff, DIFF_NORMAL);
2751 continue;
2752 }
2753 /* Infer linedsf from dline flags */
2754 if (is_atmostone(dlines, dline_index)
2755 && is_atleastone(dlines, dline_index)) {
2756 if (merge_lines(sstate, line1_index, line2_index, true))
2757 diff = min(diff, DIFF_HARD);
2758 }
2759 }
2760
2761 /* Deductions with small number of LINE_UNKNOWNs, based on overall
2762 * parity of lines. */
2763 yes = sstate->dot_yes_count[i];
2764 no = sstate->dot_no_count[i];
2765 unknown = N - yes - no;
2766 diff_tmp = parity_deductions(sstate, d->edges,
2767 yes % 2, unknown);
2768 diff = min(diff, diff_tmp);
2769 }
2770
2771 /* ------ Edge dsf deductions ------ */
2772
2773 /* If the state of a line is known, deduce the state of its canonical line
2774 * too, and vice versa. */
2775 for (i = 0; i < g->num_edges; i++) {
2776 int can;
2777 bool inv;
2778 enum line_state s;
2779 can = dsf_canonify_flip(sstate->linedsf, i, &inv);
2780 if (can == i)
2781 continue;
2782 s = sstate->state->lines[can];
2783 if (s != LINE_UNKNOWN) {
2784 if (solver_set_line(sstate, i, inv ? OPP(s) : s))
2785 diff = min(diff, DIFF_EASY);
2786 } else {
2787 s = sstate->state->lines[i];
2788 if (s != LINE_UNKNOWN) {
2789 if (solver_set_line(sstate, can, inv ? OPP(s) : s))
2790 diff = min(diff, DIFF_EASY);
2791 }
2792 }
2793 }
2794
2795 return diff;
2796}
2797
2798static int loop_deductions(solver_state *sstate)
2799{
2800 int edgecount = 0, clues = 0, satclues = 0, sm1clues = 0;
2801 game_state *state = sstate->state;
2802 grid *g = state->game_grid;
2803 int shortest_chainlen = g->num_dots;
2804 int dots_connected;
2805 bool progress = false;
2806 int i;
2807
2808 /*
2809 * Go through the grid and update for all the new edges.
2810 * Since merge_dots() is idempotent, the simplest way to
2811 * do this is just to update for _all_ the edges.
2812 * Also, while we're here, we count the edges.
2813 */
2814 for (i = 0; i < g->num_edges; i++) {
2815 if (state->lines[i] == LINE_YES) {
2816 merge_dots(sstate, i);
2817 edgecount++;
2818 }
2819 }
2820
2821 /*
2822 * Count the clues, count the satisfied clues, and count the
2823 * satisfied-minus-one clues.
2824 */
2825 for (i = 0; i < g->num_faces; i++) {
2826 int c = state->clues[i];
2827 if (c >= 0) {
2828 int o = sstate->face_yes_count[i];
2829 if (o == c)
2830 satclues++;
2831 else if (o == c-1)
2832 sm1clues++;
2833 clues++;
2834 }
2835 }
2836
2837 for (i = 0; i < g->num_dots; ++i) {
2838 dots_connected =
2839 sstate->looplen[dsf_canonify(sstate->dotdsf, i)];
2840 if (dots_connected > 1)
2841 shortest_chainlen = min(shortest_chainlen, dots_connected);
2842 }
2843
2844 assert(sstate->solver_status == SOLVER_INCOMPLETE);
2845
2846 if (satclues == clues && shortest_chainlen == edgecount) {
2847 sstate->solver_status = SOLVER_SOLVED;
2848 /* This discovery clearly counts as progress, even if we haven't
2849 * just added any lines or anything */
2850 progress = true;
2851 goto finished_loop_deductionsing;
2852 }
2853
2854 /*
2855 * Now go through looking for LINE_UNKNOWN edges which
2856 * connect two dots that are already in the same
2857 * equivalence class. If we find one, test to see if the
2858 * loop it would create is a solution.
2859 */
2860 for (i = 0; i < g->num_edges; i++) {
2861 grid_edge *e = g->edges[i];
2862 int d1 = e->dot1->index;
2863 int d2 = e->dot2->index;
2864 int eqclass, val;
2865 if (state->lines[i] != LINE_UNKNOWN)
2866 continue;
2867
2868 eqclass = dsf_canonify(sstate->dotdsf, d1);
2869 if (eqclass != dsf_canonify(sstate->dotdsf, d2))
2870 continue;
2871
2872 val = LINE_NO; /* loop is bad until proven otherwise */
2873
2874 /*
2875 * This edge would form a loop. Next
2876 * question: how long would the loop be?
2877 * Would it equal the total number of edges
2878 * (plus the one we'd be adding if we added
2879 * it)?
2880 */
2881 if (sstate->looplen[eqclass] == edgecount + 1) {
2882 int sm1_nearby;
2883
2884 /*
2885 * This edge would form a loop which
2886 * took in all the edges in the entire
2887 * grid. So now we need to work out
2888 * whether it would be a valid solution
2889 * to the puzzle, which means we have to
2890 * check if it satisfies all the clues.
2891 * This means that every clue must be
2892 * either satisfied or satisfied-minus-
2893 * 1, and also that the number of
2894 * satisfied-minus-1 clues must be at
2895 * most two and they must lie on either
2896 * side of this edge.
2897 */
2898 sm1_nearby = 0;
2899 if (e->face1) {
2900 int f = e->face1->index;
2901 int c = state->clues[f];
2902 if (c >= 0 && sstate->face_yes_count[f] == c - 1)
2903 sm1_nearby++;
2904 }
2905 if (e->face2) {
2906 int f = e->face2->index;
2907 int c = state->clues[f];
2908 if (c >= 0 && sstate->face_yes_count[f] == c - 1)
2909 sm1_nearby++;
2910 }
2911 if (sm1clues == sm1_nearby &&
2912 sm1clues + satclues == clues) {
2913 val = LINE_YES; /* loop is good! */
2914 }
2915 }
2916
2917 /*
2918 * Right. Now we know that adding this edge
2919 * would form a loop, and we know whether
2920 * that loop would be a viable solution or
2921 * not.
2922 *
2923 * If adding this edge produces a solution,
2924 * then we know we've found _a_ solution but
2925 * we don't know that it's _the_ solution -
2926 * if it were provably the solution then
2927 * we'd have deduced this edge some time ago
2928 * without the need to do loop detection. So
2929 * in this state we return SOLVER_AMBIGUOUS,
2930 * which has the effect that hitting Solve
2931 * on a user-provided puzzle will fill in a
2932 * solution but using the solver to
2933 * construct new puzzles won't consider this
2934 * a reasonable deduction for the user to
2935 * make.
2936 */
2937 progress = solver_set_line(sstate, i, val);
2938 assert(progress);
2939 if (val == LINE_YES) {
2940 sstate->solver_status = SOLVER_AMBIGUOUS;
2941 goto finished_loop_deductionsing;
2942 }
2943 }
2944
2945 finished_loop_deductionsing:
2946 return progress ? DIFF_EASY : DIFF_MAX;
2947}
2948
2949/* This will return a dynamically allocated solver_state containing the (more)
2950 * solved grid */
2951static solver_state *solve_game_rec(const solver_state *sstate_start)
2952{
2953 solver_state *sstate;
2954
2955 /* Index of the solver we should call next. */
2956 int i = 0;
2957
2958 /* As a speed-optimisation, we avoid re-running solvers that we know
2959 * won't make any progress. This happens when a high-difficulty
2960 * solver makes a deduction that can only help other high-difficulty
2961 * solvers.
2962 * For example: if a new 'dline' flag is set by dline_deductions, the
2963 * trivial_deductions solver cannot do anything with this information.
2964 * If we've already run the trivial_deductions solver (because it's
2965 * earlier in the list), there's no point running it again.
2966 *
2967 * Therefore: if a solver is earlier in the list than "threshold_index",
2968 * we don't bother running it if it's difficulty level is less than
2969 * "threshold_diff".
2970 */
2971 int threshold_diff = 0;
2972 int threshold_index = 0;
2973
2974 sstate = dup_solver_state(sstate_start);
2975
2976 check_caches(sstate);
2977
2978 while (i < NUM_SOLVERS) {
2979 if (sstate->solver_status == SOLVER_MISTAKE)
2980 return sstate;
2981 if (sstate->solver_status == SOLVER_SOLVED ||
2982 sstate->solver_status == SOLVER_AMBIGUOUS) {
2983 /* solver finished */
2984 break;
2985 }
2986
2987 if ((solver_diffs[i] >= threshold_diff || i >= threshold_index)
2988 && solver_diffs[i] <= sstate->diff) {
2989 /* current_solver is eligible, so use it */
2990 int next_diff = solver_fns[i](sstate);
2991 if (next_diff != DIFF_MAX) {
2992 /* solver made progress, so use new thresholds and
2993 * start again at top of list. */
2994 threshold_diff = next_diff;
2995 threshold_index = i;
2996 i = 0;
2997 continue;
2998 }
2999 }
3000 /* current_solver is ineligible, or failed to make progress, so
3001 * go to the next solver in the list */
3002 i++;
3003 }
3004
3005 if (sstate->solver_status == SOLVER_SOLVED ||
3006 sstate->solver_status == SOLVER_AMBIGUOUS) {
3007 /* s/LINE_UNKNOWN/LINE_NO/g */
3008 array_setall(sstate->state->lines, LINE_UNKNOWN, LINE_NO,
3009 sstate->state->game_grid->num_edges);
3010 return sstate;
3011 }
3012
3013 return sstate;
3014}
3015
3016static char *solve_game(const game_state *state, const game_state *currstate,
3017 const char *aux, const char **error)
3018{
3019 char *soln = NULL;
3020 solver_state *sstate, *new_sstate;
3021
3022 sstate = new_solver_state(state, DIFF_MAX);
3023 new_sstate = solve_game_rec(sstate);
3024
3025 if (new_sstate->solver_status == SOLVER_SOLVED) {
3026 soln = encode_solve_move(new_sstate->state);
3027 } else if (new_sstate->solver_status == SOLVER_AMBIGUOUS) {
3028 soln = encode_solve_move(new_sstate->state);
3029 /**error = "Solver found ambiguous solutions"; */
3030 } else {
3031 soln = encode_solve_move(new_sstate->state);
3032 /**error = "Solver failed"; */
3033 }
3034
3035 free_solver_state(new_sstate);
3036 free_solver_state(sstate);
3037
3038 return soln;
3039}
3040
3041/* ----------------------------------------------------------------------
3042 * Drawing and mouse-handling
3043 */
3044
3045static char *interpret_move(const game_state *state, game_ui *ui,
3046 const game_drawstate *ds,
3047 int x, int y, int button)
3048{
3049 grid *g = state->game_grid;
3050 grid_edge *e;
3051 int i;
3052 char *movebuf;
3053 int movelen, movesize;
3054 char button_char = ' ';
3055 enum line_state old_state;
3056
3057 button = STRIP_BUTTON_MODIFIERS(button);
3058
3059 /* Convert mouse-click (x,y) to grid coordinates */
3060 x -= BORDER(ds->tilesize);
3061 y -= BORDER(ds->tilesize);
3062 x = x * g->tilesize / ds->tilesize;
3063 y = y * g->tilesize / ds->tilesize;
3064 x += g->lowest_x;
3065 y += g->lowest_y;
3066
3067 e = grid_nearest_edge(g, x, y);
3068 if (e == NULL)
3069 return NULL;
3070
3071 i = e->index;
3072
3073 /* I think it's only possible to play this game with mouse clicks, sorry */
3074 /* Maybe will add mouse drag support some time */
3075 old_state = state->lines[i];
3076
3077 switch (button) {
3078 case LEFT_BUTTON:
3079 switch (old_state) {
3080 case LINE_UNKNOWN:
3081 button_char = 'y';
3082 break;
3083 case LINE_YES:
3084#ifdef STYLUS_BASED
3085 button_char = 'n';
3086 break;
3087#endif
3088 case LINE_NO:
3089 button_char = 'u';
3090 break;
3091 }
3092 break;
3093 case MIDDLE_BUTTON:
3094 button_char = 'u';
3095 break;
3096 case RIGHT_BUTTON:
3097 switch (old_state) {
3098 case LINE_UNKNOWN:
3099 button_char = 'n';
3100 break;
3101 case LINE_NO:
3102#ifdef STYLUS_BASED
3103 button_char = 'y';
3104 break;
3105#endif
3106 case LINE_YES:
3107 button_char = 'u';
3108 break;
3109 }
3110 break;
3111 default:
3112 return NULL;
3113 }
3114
3115 movelen = 0;
3116 movesize = 80;
3117 movebuf = snewn(movesize, char);
3118 movelen = sprintf(movebuf, "%d%c", i, (int)button_char);
3119
3120 if (ui->autofollow != AF_OFF) {
3121 int dotid;
3122 for (dotid = 0; dotid < 2; dotid++) {
3123 grid_dot *dot = (dotid == 0 ? e->dot1 : e->dot2);
3124 grid_edge *e_this = e;
3125
3126 while (1) {
3127 int j, n_found;
3128 grid_edge *e_next = NULL;
3129
3130 for (j = n_found = 0; j < dot->order; j++) {
3131 grid_edge *e_candidate = dot->edges[j];
3132 int i_candidate = e_candidate->index;
3133 if (e_candidate != e_this &&
3134 (ui->autofollow == AF_FIXED ||
3135 state->lines[i] == LINE_NO ||
3136 state->lines[i_candidate] != LINE_NO)) {
3137 e_next = e_candidate;
3138 n_found++;
3139 }
3140 }
3141
3142 if (n_found != 1 ||
3143 state->lines[e_next->index] != state->lines[i])
3144 break;
3145
3146 if (e_next == e) {
3147 /*
3148 * Special case: we might have come all the way
3149 * round a loop and found our way back to the same
3150 * edge we started from. In that situation, we
3151 * must terminate not only this while loop, but
3152 * the 'for' outside it that was tracing in both
3153 * directions from the starting edge, because if
3154 * we let it trace in the second direction then
3155 * we'll only find ourself traversing the same
3156 * loop in the other order and generate an encoded
3157 * move string that mentions the same set of edges
3158 * twice.
3159 */
3160 goto autofollow_done;
3161 }
3162
3163 dot = (e_next->dot1 != dot ? e_next->dot1 : e_next->dot2);
3164 if (movelen > movesize - 40) {
3165 movesize = movesize * 5 / 4 + 128;
3166 movebuf = sresize(movebuf, movesize, char);
3167 }
3168 e_this = e_next;
3169 movelen += sprintf(movebuf+movelen, "%d%c",
3170 (int)(e_this->index), button_char);
3171 }
3172 autofollow_done:;
3173 }
3174 }
3175
3176 return sresize(movebuf, movelen+1, char);
3177}
3178
3179static game_state *execute_move(const game_state *state, const char *move)
3180{
3181 int i;
3182 game_state *newstate = dup_game(state);
3183
3184 if (move[0] == 'S') {
3185 move++;
3186 newstate->cheated = true;
3187 }
3188
3189 while (*move) {
3190 i = atoi(move);
3191 if (i < 0 || i >= newstate->game_grid->num_edges)
3192 goto fail;
3193 move += strspn(move, "1234567890");
3194 switch (*(move++)) {
3195 case 'y':
3196 newstate->lines[i] = LINE_YES;
3197 break;
3198 case 'n':
3199 newstate->lines[i] = LINE_NO;
3200 break;
3201 case 'u':
3202 newstate->lines[i] = LINE_UNKNOWN;
3203 break;
3204 default:
3205 goto fail;
3206 }
3207 }
3208
3209 /*
3210 * Check for completion.
3211 */
3212 if (check_completion(newstate))
3213 newstate->solved = true;
3214
3215 return newstate;
3216
3217 fail:
3218 free_game(newstate);
3219 return NULL;
3220}
3221
3222/* ----------------------------------------------------------------------
3223 * Drawing routines.
3224 */
3225
3226/* Convert from grid coordinates to screen coordinates */
3227static void grid_to_screen(const game_drawstate *ds, const grid *g,
3228 int grid_x, int grid_y, int *x, int *y)
3229{
3230 *x = grid_x - g->lowest_x;
3231 *y = grid_y - g->lowest_y;
3232 *x = *x * ds->tilesize / g->tilesize;
3233 *y = *y * ds->tilesize / g->tilesize;
3234 *x += BORDER(ds->tilesize);
3235 *y += BORDER(ds->tilesize);
3236}
3237
3238/* Returns (into x,y) position of centre of face for rendering the text clue.
3239 */
3240static void face_text_pos(const game_drawstate *ds, const grid *g,
3241 grid_face *f, int *xret, int *yret)
3242{
3243 int faceindex = f->index;
3244
3245 /*
3246 * Return the cached position for this face, if we've already
3247 * worked it out.
3248 */
3249 if (ds->textx[faceindex] >= 0) {
3250 *xret = ds->textx[faceindex];
3251 *yret = ds->texty[faceindex];
3252 return;
3253 }
3254
3255 /*
3256 * Otherwise, use the incentre computed by grid.c and convert it
3257 * to screen coordinates.
3258 */
3259 grid_find_incentre(f);
3260 grid_to_screen(ds, g, f->ix, f->iy,
3261 &ds->textx[faceindex], &ds->texty[faceindex]);
3262
3263 *xret = ds->textx[faceindex];
3264 *yret = ds->texty[faceindex];
3265}
3266
3267static void face_text_bbox(game_drawstate *ds, grid *g, grid_face *f,
3268 int *x, int *y, int *w, int *h)
3269{
3270 int xx, yy;
3271 face_text_pos(ds, g, f, &xx, &yy);
3272
3273 /* There seems to be a certain amount of trial-and-error involved
3274 * in working out the correct bounding-box for the text. */
3275
3276 *x = xx - ds->tilesize * 5 / 4 - 1;
3277 *y = yy - ds->tilesize/4 - 3;
3278 *w = ds->tilesize * 5 / 2 + 2;
3279 *h = ds->tilesize/2 + 5;
3280}
3281
3282static void game_redraw_clue(drawing *dr, game_drawstate *ds,
3283 const game_state *state, int i)
3284{
3285 grid *g = state->game_grid;
3286 grid_face *f = g->faces[i];
3287 int x, y;
3288 char c[20];
3289
3290 sprintf(c, "%d", state->clues[i]);
3291
3292 face_text_pos(ds, g, f, &x, &y);
3293 draw_text(dr, x, y,
3294 FONT_VARIABLE, ds->tilesize/2,
3295 ALIGN_VCENTRE | ALIGN_HCENTRE,
3296 ds->clue_error[i] ? COL_MISTAKE :
3297 ds->clue_satisfied[i] ? COL_SATISFIED : COL_FOREGROUND, c);
3298}
3299
3300static void edge_bbox(game_drawstate *ds, grid *g, grid_edge *e,
3301 int *x, int *y, int *w, int *h)
3302{
3303 int x1 = e->dot1->x;
3304 int y1 = e->dot1->y;
3305 int x2 = e->dot2->x;
3306 int y2 = e->dot2->y;
3307 int xmin, xmax, ymin, ymax;
3308
3309 grid_to_screen(ds, g, x1, y1, &x1, &y1);
3310 grid_to_screen(ds, g, x2, y2, &x2, &y2);
3311 /* Allow extra margin for dots, and thickness of lines */
3312 xmin = min(x1, x2) - (ds->tilesize + 15) / 16;
3313 xmax = max(x1, x2) + (ds->tilesize + 15) / 16;
3314 ymin = min(y1, y2) - (ds->tilesize + 15) / 16;
3315 ymax = max(y1, y2) + (ds->tilesize + 15) / 16;
3316
3317 *x = xmin;
3318 *y = ymin;
3319 *w = xmax - xmin + 1;
3320 *h = ymax - ymin + 1;
3321}
3322
3323static void dot_bbox(game_drawstate *ds, grid *g, grid_dot *d,
3324 int *x, int *y, int *w, int *h)
3325{
3326 int x1, y1;
3327 int xmin, xmax, ymin, ymax;
3328
3329 grid_to_screen(ds, g, d->x, d->y, &x1, &y1);
3330
3331 xmin = x1 - (ds->tilesize * 5 + 63) / 64;
3332 xmax = x1 + (ds->tilesize * 5 + 63) / 64;
3333 ymin = y1 - (ds->tilesize * 5 + 63) / 64;
3334 ymax = y1 + (ds->tilesize * 5 + 63) / 64;
3335
3336 *x = xmin;
3337 *y = ymin;
3338 *w = xmax - xmin + 1;
3339 *h = ymax - ymin + 1;
3340}
3341
3342static const int loopy_line_redraw_phases[] = {
3343 COL_FAINT, COL_LINEUNKNOWN, COL_FOREGROUND, COL_HIGHLIGHT, COL_MISTAKE
3344};
3345#define NPHASES lenof(loopy_line_redraw_phases)
3346
3347static void game_redraw_line(drawing *dr, game_drawstate *ds,const game_ui *ui,
3348 const game_state *state, int i, int phase)
3349{
3350 grid *g = state->game_grid;
3351 grid_edge *e = g->edges[i];
3352 int x1, x2, y1, y2;
3353 int line_colour;
3354
3355 if (state->line_errors[i])
3356 line_colour = COL_MISTAKE;
3357 else if (state->lines[i] == LINE_UNKNOWN)
3358 line_colour = COL_LINEUNKNOWN;
3359 else if (state->lines[i] == LINE_NO)
3360 line_colour = COL_FAINT;
3361 else if (ds->flashing)
3362 line_colour = COL_HIGHLIGHT;
3363 else
3364 line_colour = COL_FOREGROUND;
3365 if (line_colour != loopy_line_redraw_phases[phase])
3366 return;
3367
3368 /* Convert from grid to screen coordinates */
3369 grid_to_screen(ds, g, e->dot1->x, e->dot1->y, &x1, &y1);
3370 grid_to_screen(ds, g, e->dot2->x, e->dot2->y, &x2, &y2);
3371
3372 if (line_colour == COL_FAINT) {
3373 if (ui->draw_faint_lines)
3374 draw_thick_line(dr, ds->tilesize/24.0,
3375 x1 + 0.5, y1 + 0.5,
3376 x2 + 0.5, y2 + 0.5,
3377 line_colour);
3378 } else {
3379 draw_thick_line(dr, ds->tilesize*3/32.0,
3380 x1 + 0.5, y1 + 0.5,
3381 x2 + 0.5, y2 + 0.5,
3382 line_colour);
3383 }
3384}
3385
3386static void game_redraw_dot(drawing *dr, game_drawstate *ds,
3387 const game_state *state, int i)
3388{
3389 grid *g = state->game_grid;
3390 grid_dot *d = g->dots[i];
3391 int x, y;
3392
3393 grid_to_screen(ds, g, d->x, d->y, &x, &y);
3394 draw_circle(dr, x, y, ds->tilesize*2.5/32.0, COL_FOREGROUND, COL_FOREGROUND);
3395}
3396
3397static bool boxes_intersect(int x0, int y0, int w0, int h0,
3398 int x1, int y1, int w1, int h1)
3399{
3400 /*
3401 * Two intervals intersect iff neither is wholly on one side of
3402 * the other. Two boxes intersect iff their horizontal and
3403 * vertical intervals both intersect.
3404 */
3405 return (x0 < x1+w1 && x1 < x0+w0 && y0 < y1+h1 && y1 < y0+h0);
3406}
3407
3408static void game_redraw_in_rect(drawing *dr, game_drawstate *ds,
3409 const game_ui *ui, const game_state *state,
3410 int x, int y, int w, int h)
3411{
3412 grid *g = state->game_grid;
3413 int i, phase;
3414 int bx, by, bw, bh;
3415
3416 clip(dr, x, y, w, h);
3417 draw_rect(dr, x, y, w, h, COL_BACKGROUND);
3418
3419 for (i = 0; i < g->num_faces; i++) {
3420 if (state->clues[i] >= 0) {
3421 face_text_bbox(ds, g, g->faces[i], &bx, &by, &bw, &bh);
3422 if (boxes_intersect(x, y, w, h, bx, by, bw, bh))
3423 game_redraw_clue(dr, ds, state, i);
3424 }
3425 }
3426 for (phase = 0; phase < NPHASES; phase++) {
3427 for (i = 0; i < g->num_edges; i++) {
3428 edge_bbox(ds, g, g->edges[i], &bx, &by, &bw, &bh);
3429 if (boxes_intersect(x, y, w, h, bx, by, bw, bh))
3430 game_redraw_line(dr, ds, ui, state, i, phase);
3431 }
3432 }
3433 for (i = 0; i < g->num_dots; i++) {
3434 dot_bbox(ds, g, g->dots[i], &bx, &by, &bw, &bh);
3435 if (boxes_intersect(x, y, w, h, bx, by, bw, bh))
3436 game_redraw_dot(dr, ds, state, i);
3437 }
3438
3439 unclip(dr);
3440 draw_update(dr, x, y, w, h);
3441}
3442
3443static void game_redraw(drawing *dr, game_drawstate *ds,
3444 const game_state *oldstate, const game_state *state,
3445 int dir, const game_ui *ui,
3446 float animtime, float flashtime)
3447{
3448#define REDRAW_OBJECTS_LIMIT 16 /* Somewhat arbitrary tradeoff */
3449
3450 grid *g = state->game_grid;
3451 int border = BORDER(ds->tilesize);
3452 int i;
3453 bool flash_changed;
3454 bool redraw_everything = false;
3455
3456 int edges[REDRAW_OBJECTS_LIMIT], nedges = 0;
3457 int faces[REDRAW_OBJECTS_LIMIT], nfaces = 0;
3458
3459 /* Redrawing is somewhat involved.
3460 *
3461 * An update can theoretically affect an arbitrary number of edges
3462 * (consider, for example, completing or breaking a cycle which doesn't
3463 * satisfy all the clues -- we'll switch many edges between error and
3464 * normal states). On the other hand, redrawing the whole grid takes a
3465 * while, making the game feel sluggish, and many updates are actually
3466 * quite well localized.
3467 *
3468 * This redraw algorithm attempts to cope with both situations gracefully
3469 * and correctly. For localized changes, we set a clip rectangle, fill
3470 * it with background, and then redraw (a plausible but conservative
3471 * guess at) the objects which intersect the rectangle; if several
3472 * objects need redrawing, we'll do them individually. However, if lots
3473 * of objects are affected, we'll just redraw everything.
3474 *
3475 * The reason for all of this is that it's just not safe to do the redraw
3476 * piecemeal. If you try to draw an antialiased diagonal line over
3477 * itself, you get a slightly thicker antialiased diagonal line, which
3478 * looks rather ugly after a while.
3479 *
3480 * So, we take two passes over the grid. The first attempts to work out
3481 * what needs doing, and the second actually does it.
3482 */
3483
3484 if (!ds->started) {
3485 redraw_everything = true;
3486 /*
3487 * But we must still go through the upcoming loops, so that we
3488 * set up stuff in ds correctly for the initial redraw.
3489 */
3490 }
3491
3492 /* First, trundle through the faces. */
3493 for (i = 0; i < g->num_faces; i++) {
3494 grid_face *f = g->faces[i];
3495 int sides = f->order;
3496 int yes_order, no_order;
3497 bool clue_mistake;
3498 bool clue_satisfied;
3499 int n = state->clues[i];
3500 if (n < 0)
3501 continue;
3502
3503 yes_order = face_order(state, i, LINE_YES);
3504 if (state->exactly_one_loop) {
3505 /*
3506 * Special case: if the set of LINE_YES edges in the grid
3507 * consists of exactly one loop and nothing else, then we
3508 * switch to treating LINE_UNKNOWN the same as LINE_NO for
3509 * purposes of clue checking.
3510 *
3511 * This is because some people like to play Loopy without
3512 * using the right-click, i.e. never setting anything to
3513 * LINE_NO. Without this special case, if a person playing
3514 * in that style fills in what they think is a correct
3515 * solution loop but in fact it has an underfilled clue,
3516 * then we will display no victory flash and also no error
3517 * highlight explaining why not. With this special case,
3518 * we light up underfilled clues at the instant the loop
3519 * is closed. (Of course, *overfilled* clues are fine
3520 * either way.)
3521 *
3522 * (It might still be considered unfortunate that we can't
3523 * warn this style of player any earlier, if they make a
3524 * mistake very near the beginning which doesn't show up
3525 * until they close the last edge of the loop. One other
3526 * thing we _could_ do here is to treat any LINE_UNKNOWN
3527 * as LINE_NO if either of its endpoints has yes-degree 2,
3528 * reflecting the fact that setting that line to YES would
3529 * be an obvious error. But I don't think even that could
3530 * catch _all_ clue errors in a timely manner; I think
3531 * there are some that won't be displayed until the loop
3532 * is filled in, even so, and there's no way to avoid that
3533 * with complete reliability except to switch to being a
3534 * player who sets things to LINE_NO.)
3535 */
3536 no_order = sides - yes_order;
3537 } else {
3538 no_order = face_order(state, i, LINE_NO);
3539 }
3540
3541 clue_mistake = (yes_order > n || no_order > (sides-n));
3542 clue_satisfied = (yes_order == n && no_order == (sides-n));
3543
3544 if (clue_mistake != ds->clue_error[i] ||
3545 clue_satisfied != ds->clue_satisfied[i]) {
3546 ds->clue_error[i] = clue_mistake;
3547 ds->clue_satisfied[i] = clue_satisfied;
3548 if (nfaces == REDRAW_OBJECTS_LIMIT)
3549 redraw_everything = true;
3550 else
3551 faces[nfaces++] = i;
3552 }
3553 }
3554
3555 /* Work out what the flash state needs to be. */
3556 if (flashtime > 0 &&
3557 (flashtime <= FLASH_TIME/3 ||
3558 flashtime >= FLASH_TIME*2/3)) {
3559 flash_changed = !ds->flashing;
3560 ds->flashing = true;
3561 } else {
3562 flash_changed = ds->flashing;
3563 ds->flashing = false;
3564 }
3565
3566 /* Now, trundle through the edges. */
3567 for (i = 0; i < g->num_edges; i++) {
3568 char new_ds =
3569 state->line_errors[i] ? DS_LINE_ERROR : state->lines[i];
3570 if (new_ds != ds->lines[i] ||
3571 (flash_changed && state->lines[i] == LINE_YES)) {
3572 ds->lines[i] = new_ds;
3573 if (nedges == REDRAW_OBJECTS_LIMIT)
3574 redraw_everything = true;
3575 else
3576 edges[nedges++] = i;
3577 }
3578 }
3579
3580 /* Pass one is now done. Now we do the actual drawing. */
3581 if (redraw_everything) {
3582 int grid_width = g->highest_x - g->lowest_x;
3583 int grid_height = g->highest_y - g->lowest_y;
3584 int w = grid_width * ds->tilesize / g->tilesize;
3585 int h = grid_height * ds->tilesize / g->tilesize;
3586
3587 game_redraw_in_rect(dr, ds, ui, state,
3588 0, 0, w + 2*border + 1, h + 2*border + 1);
3589 } else {
3590
3591 /* Right. Now we roll up our sleeves. */
3592
3593 for (i = 0; i < nfaces; i++) {
3594 grid_face *f = g->faces[faces[i]];
3595 int x, y, w, h;
3596
3597 face_text_bbox(ds, g, f, &x, &y, &w, &h);
3598 game_redraw_in_rect(dr, ds, ui, state, x, y, w, h);
3599 }
3600
3601 for (i = 0; i < nedges; i++) {
3602 grid_edge *e = g->edges[edges[i]];
3603 int x, y, w, h;
3604
3605 edge_bbox(ds, g, e, &x, &y, &w, &h);
3606 game_redraw_in_rect(dr, ds, ui, state, x, y, w, h);
3607 }
3608 }
3609
3610 ds->started = true;
3611}
3612
3613static float game_flash_length(const game_state *oldstate,
3614 const game_state *newstate, int dir, game_ui *ui)
3615{
3616 if (!oldstate->solved && newstate->solved &&
3617 !oldstate->cheated && !newstate->cheated) {
3618 return FLASH_TIME;
3619 }
3620
3621 return 0.0F;
3622}
3623
3624static void game_get_cursor_location(const game_ui *ui,
3625 const game_drawstate *ds,
3626 const game_state *state,
3627 const game_params *params,
3628 int *x, int *y, int *w, int *h)
3629{
3630}
3631
3632static int game_status(const game_state *state)
3633{
3634 return state->solved ? +1 : 0;
3635}
3636
3637static void game_print_size(const game_params *params, const game_ui *ui,
3638 float *x, float *y)
3639{
3640 int pw, ph;
3641
3642 /*
3643 * I'll use 7mm "squares" by default.
3644 */
3645 game_compute_size(params, 700, ui, &pw, &ph);
3646 *x = pw / 100.0F;
3647 *y = ph / 100.0F;
3648}
3649
3650static void game_print(drawing *dr, const game_state *state, const game_ui *ui,
3651 int tilesize)
3652{
3653 int ink = print_mono_colour(dr, 0);
3654 int i;
3655 game_drawstate ads, *ds = &ads;
3656 grid *g = state->game_grid;
3657
3658 ds->tilesize = tilesize;
3659 ds->textx = snewn(g->num_faces, int);
3660 ds->texty = snewn(g->num_faces, int);
3661 for (i = 0; i < g->num_faces; i++)
3662 ds->textx[i] = ds->texty[i] = -1;
3663
3664 for (i = 0; i < g->num_dots; i++) {
3665 int x, y;
3666 grid_to_screen(ds, g, g->dots[i]->x, g->dots[i]->y, &x, &y);
3667 draw_circle(dr, x, y, ds->tilesize / 15, ink, ink);
3668 }
3669
3670 /*
3671 * Clues.
3672 */
3673 for (i = 0; i < g->num_faces; i++) {
3674 grid_face *f = g->faces[i];
3675 int clue = state->clues[i];
3676 if (clue >= 0) {
3677 char c[20];
3678 int x, y;
3679 sprintf(c, "%d", state->clues[i]);
3680 face_text_pos(ds, g, f, &x, &y);
3681 draw_text(dr, x, y,
3682 FONT_VARIABLE, ds->tilesize / 2,
3683 ALIGN_VCENTRE | ALIGN_HCENTRE, ink, c);
3684 }
3685 }
3686
3687 /*
3688 * Lines.
3689 */
3690 for (i = 0; i < g->num_edges; i++) {
3691 int thickness = (state->lines[i] == LINE_YES) ? 30 : 150;
3692 grid_edge *e = g->edges[i];
3693 int x1, y1, x2, y2;
3694 grid_to_screen(ds, g, e->dot1->x, e->dot1->y, &x1, &y1);
3695 grid_to_screen(ds, g, e->dot2->x, e->dot2->y, &x2, &y2);
3696 if (state->lines[i] == LINE_YES)
3697 {
3698 /* (dx, dy) points from (x1, y1) to (x2, y2).
3699 * The line is then "fattened" in a perpendicular
3700 * direction to create a thin rectangle. */
3701 double d = sqrt(SQ((double)x1 - x2) + SQ((double)y1 - y2));
3702 double dx = (x2 - x1) / d;
3703 double dy = (y2 - y1) / d;
3704 int points[8];
3705
3706 dx = (dx * ds->tilesize) / thickness;
3707 dy = (dy * ds->tilesize) / thickness;
3708 points[0] = x1 + (int)dy;
3709 points[1] = y1 - (int)dx;
3710 points[2] = x1 - (int)dy;
3711 points[3] = y1 + (int)dx;
3712 points[4] = x2 - (int)dy;
3713 points[5] = y2 + (int)dx;
3714 points[6] = x2 + (int)dy;
3715 points[7] = y2 - (int)dx;
3716 draw_polygon(dr, points, 4, ink, ink);
3717 }
3718 else
3719 {
3720 /* Draw a dotted line */
3721 int divisions = 6;
3722 int j;
3723 for (j = 1; j < divisions; j++) {
3724 /* Weighted average */
3725 int x = (x1 * (divisions -j) + x2 * j) / divisions;
3726 int y = (y1 * (divisions -j) + y2 * j) / divisions;
3727 draw_circle(dr, x, y, ds->tilesize / thickness, ink, ink);
3728 }
3729 }
3730 }
3731
3732 sfree(ds->textx);
3733 sfree(ds->texty);
3734}
3735
3736#ifdef COMBINED
3737#define thegame loopy
3738#endif
3739
3740const struct game thegame = {
3741 "Loopy", "games.loopy", "loopy",
3742 default_params,
3743 NULL, game_preset_menu,
3744 decode_params,
3745 encode_params,
3746 free_params,
3747 dup_params,
3748 true, game_configure, custom_params,
3749 validate_params,
3750 new_game_desc,
3751 validate_desc,
3752 new_game,
3753 dup_game,
3754 free_game,
3755 true, solve_game,
3756 true, game_can_format_as_text_now, game_text_format,
3757 get_prefs, set_prefs,
3758 new_ui,
3759 free_ui,
3760 NULL, /* encode_ui */
3761 NULL, /* decode_ui */
3762 NULL, /* game_request_keys */
3763 game_changed_state,
3764 NULL, /* current_key_label */
3765 interpret_move,
3766 execute_move,
3767 PREFERRED_TILE_SIZE, game_compute_size, game_set_size,
3768 game_colours,
3769 game_new_drawstate,
3770 game_free_drawstate,
3771 game_redraw,
3772 game_anim_length,
3773 game_flash_length,
3774 game_get_cursor_location,
3775 game_status,
3776 true, false, game_print_size, game_print,
3777 false /* wants_statusbar */,
3778 false, NULL, /* timing_state */
3779 0, /* mouse_priorities */
3780};
3781
3782#ifdef STANDALONE_SOLVER
3783
3784/*
3785 * Half-hearted standalone solver. It can't output the solution to
3786 * anything but a square puzzle, and it can't log the deductions
3787 * it makes either. But it can solve square puzzles, and more
3788 * importantly it can use its solver to grade the difficulty of
3789 * any puzzle you give it.
3790 */
3791
3792#include <stdarg.h>
3793
3794int main(int argc, char **argv)
3795{
3796 game_params *p;
3797 game_state *s;
3798 char *id = NULL, *desc;
3799 const char *err;
3800 bool grade = false;
3801 int ret, diff;
3802#if 0 /* verbose solver not supported here (yet) */
3803 bool really_verbose = false;
3804#endif
3805
3806 while (--argc > 0) {
3807 char *p = *++argv;
3808#if 0 /* verbose solver not supported here (yet) */
3809 if (!strcmp(p, "-v")) {
3810 really_verbose = true;
3811 } else
3812#endif
3813 if (!strcmp(p, "-g")) {
3814 grade = true;
3815 } else if (*p == '-') {
3816 fprintf(stderr, "%s: unrecognised option `%s'\n", argv[0], p);
3817 return 1;
3818 } else {
3819 id = p;
3820 }
3821 }
3822
3823 if (!id) {
3824 fprintf(stderr, "usage: %s [-g | -v] <game_id>\n", argv[0]);
3825 return 1;
3826 }
3827
3828 desc = strchr(id, ':');
3829 if (!desc) {
3830 fprintf(stderr, "%s: game id expects a colon in it\n", argv[0]);
3831 return 1;
3832 }
3833 *desc++ = '\0';
3834
3835 p = default_params();
3836 decode_params(p, id);
3837 err = validate_desc(p, desc);
3838 if (err) {
3839 fprintf(stderr, "%s: %s\n", argv[0], err);
3840 return 1;
3841 }
3842 s = new_game(NULL, p, desc);
3843
3844 /*
3845 * When solving an Easy puzzle, we don't want to bother the
3846 * user with Hard-level deductions. For this reason, we grade
3847 * the puzzle internally before doing anything else.
3848 */
3849 ret = -1; /* placate optimiser */
3850 for (diff = 0; diff < DIFF_MAX; diff++) {
3851 solver_state *sstate_new;
3852 solver_state *sstate = new_solver_state((game_state *)s, diff);
3853
3854 sstate_new = solve_game_rec(sstate);
3855
3856 if (sstate_new->solver_status == SOLVER_MISTAKE)
3857 ret = 0;
3858 else if (sstate_new->solver_status == SOLVER_SOLVED)
3859 ret = 1;
3860 else
3861 ret = 2;
3862
3863 free_solver_state(sstate_new);
3864 free_solver_state(sstate);
3865
3866 if (ret < 2)
3867 break;
3868 }
3869
3870 if (diff == DIFF_MAX) {
3871 if (grade)
3872 printf("Difficulty rating: harder than Hard, or ambiguous\n");
3873 else
3874 printf("Unable to find a unique solution\n");
3875 } else {
3876 if (grade) {
3877 if (ret == 0)
3878 printf("Difficulty rating: impossible (no solution exists)\n");
3879 else if (ret == 1)
3880 printf("Difficulty rating: %s\n", diffnames[diff]);
3881 } else {
3882 solver_state *sstate_new;
3883 solver_state *sstate = new_solver_state((game_state *)s, diff);
3884
3885 /* If we supported a verbose solver, we'd set verbosity here */
3886
3887 sstate_new = solve_game_rec(sstate);
3888
3889 if (sstate_new->solver_status == SOLVER_MISTAKE)
3890 printf("Puzzle is inconsistent\n");
3891 else {
3892 assert(sstate_new->solver_status == SOLVER_SOLVED);
3893 if (s->grid_type == 0) {
3894 fputs(game_text_format(sstate_new->state), stdout);
3895 } else {
3896 printf("Unable to output non-square grids\n");
3897 }
3898 }
3899
3900 free_solver_state(sstate_new);
3901 free_solver_state(sstate);
3902 }
3903 }
3904
3905 return 0;
3906}
3907
3908#endif
3909
3910/* vim: set shiftwidth=4 tabstop=8: */