regnault.dev
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Day 7
+2
src/aoc.gleam
+2
src/aoc.gleam
···
6
6
import days/day4
7
7
import days/day5
8
8
import days/day6
9
+
import days/day7
9
10
import gleam/erlang
10
11
import gleam/int
11
12
import gleam/io
···
31
32
4 -> day4.start()
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33
5 -> day5.start()
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34
6 -> day6.start()
35
+
7 -> day7.start()
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_ -> io.println("Tried to run day " <> int.to_string(day))
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37
}
36
38
birl.now()
+164
src/days/day7.gleam
+164
src/days/day7.gleam
···
1
+
import gleam/dict
2
+
import gleam/float
3
+
import gleam/function
4
+
import gleam/int
5
+
import gleam/io
6
+
import gleam/list
7
+
import gleam/otp/task
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+
import gleam/result
9
+
import gleam/set
10
+
import gleam/string
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+
import simplifile
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import utils/utils
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+
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type Type {
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Tachion
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Splitter
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}
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+
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+
type Position {
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Position(x: Int)
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+
}
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+
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+
type Cell {
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+
Cell(pos: Position, typ: Type)
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+
}
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+
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+
pub fn start() -> Nil {
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+
let assert Ok(content) = simplifile.read("inputs/day7.txt")
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+
let data = parse(content)
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+
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+
let _ = io.debug(part1(data))
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+
let _ = io.debug(part2(data))
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+
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+
Nil
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+
}
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+
37
+
fn parse(data: String) {
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+
string.split(data, "\n")
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+
|> list.index_map(fn(l, y) {
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+
list.index_map(string.to_graphemes(l), fn(c, x) {
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+
case c {
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+
"S" -> Ok(Cell(Position(x), Tachion))
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+
"^" -> Ok(Cell(Position(x), Splitter))
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+
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+
// Should never happen
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+
_ -> Error(Nil)
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+
}
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+
})
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+
|> list.filter_map(function.identity)
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+
})
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+
|> list.filter(fn(x) { !list.is_empty(x) })
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+
}
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+
54
+
type Res {
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+
Res(splits: Int, tachions: List(Cell))
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+
}
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+
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+
fn part1(data: List(List(Cell))) {
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+
let res =
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+
list.fold(data, Res(0, []), fn(acc, cells_on_line) {
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+
let new_tachions =
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+
list.map(cells_on_line, fn(c) {
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+
case c.typ {
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+
Tachion -> #([c], 0, [])
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+
Splitter -> {
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+
let Position(cx) = c.pos
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+
case list.find(acc.tachions, fn(x) { x.pos.x == cx }) {
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+
Ok(c) -> #(
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+
[
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+
Cell(Position(cx - 1), Tachion),
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+
Cell(Position(cx + 1), Tachion),
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+
],
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+
1,
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+
[c],
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+
)
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+
Error(_) -> #([], 0, [])
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+
}
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+
}
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+
}
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+
})
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+
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+
let used_tachions =
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+
list.fold(new_tachions, [], fn(acc, x) { [x.2, ..acc] })
84
+
|> list.flatten
85
+
|> list.fold(set.new(), set.insert)
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+
|> set.to_list
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+
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+
let new_splits =
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+
acc.splits + list.fold(new_tachions, 0, fn(acc, t) { acc + t.1 })
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+
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+
let new_tachions =
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+
list.map(new_tachions, fn(x) { x.0 })
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+
|> list.filter(fn(x) { !list.is_empty(x) })
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+
|> list.flatten
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+
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+
let tachions =
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+
list.filter(acc.tachions, fn(x) { !list.contains(used_tachions, x) })
98
+
|> list.append(new_tachions)
99
+
|> list.fold(set.new(), set.insert)
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+
|> set.to_list
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+
102
+
Res(new_splits, tachions)
103
+
})
104
+
105
+
res.splits
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+
}
107
+
108
+
type Cache =
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+
dict.Dict(#(Int, Int), Int)
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+
111
+
fn rec(
112
+
line: Int,
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+
next: List(List(Cell)),
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+
depth: Int,
115
+
cache: Cache,
116
+
) -> #(Int, Cache) {
117
+
let next_splitter =
118
+
utils.list_find_indexes(next, fn(x) {
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+
result.is_ok(list.find(x, fn(y) { y.pos.x == line && y.typ == Splitter }))
120
+
})
121
+
|> list.filter(fn(x) { x > depth })
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+
|> list.first()
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+
124
+
case next_splitter {
125
+
Ok(lidx) -> {
126
+
let assert Ok(l) = list.drop(next, lidx) |> list.first
127
+
let assert Ok(splitter) =
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+
list.find(l, fn(y) { y.pos.x == line && y.typ == Splitter })
129
+
130
+
// Check left Side
131
+
let #(left, cache) = case
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+
dict.has_key(cache, #(splitter.pos.x - 1, lidx))
133
+
{
134
+
True -> {
135
+
let assert Ok(v) = dict.get(cache, #(splitter.pos.x - 1, lidx))
136
+
#(v, cache)
137
+
}
138
+
False -> rec(splitter.pos.x - 1, next, lidx, cache)
139
+
}
140
+
let cache = dict.insert(cache, #(splitter.pos.x - 1, lidx), left)
141
+
142
+
// Check right Side
143
+
let #(right, cache) = case
144
+
dict.has_key(cache, #(splitter.pos.x + 1, lidx))
145
+
{
146
+
True -> {
147
+
let assert Ok(v) = dict.get(cache, #(splitter.pos.x + 1, lidx))
148
+
#(v, cache)
149
+
}
150
+
False -> rec(splitter.pos.x + 1, next, lidx, cache)
151
+
}
152
+
let cache = dict.insert(cache, #(splitter.pos.x + 1, lidx), right)
153
+
154
+
#(left + right, cache)
155
+
}
156
+
Error(_) -> #(1, cache)
157
+
}
158
+
}
159
+
160
+
fn part2(data: List(List(Cell))) {
161
+
let assert Ok(fl) = list.first(data)
162
+
let assert Ok(t) = list.first(fl)
163
+
rec(t.pos.x, data, 0, dict.new()).0
164
+
}