bwc9876.dev
Advent of Code solutions
Day 4
+83
-8
+7
utils/src/grid.rs
+7
utils/src/grid.rs
···
156
156
.and_then(|row| row.get(pos.x as usize))
157
157
}
158
158
159
+
/// Obtain a mutable reference to a tile in the grid
160
+
pub fn get_mut<'a>(&'a mut self, pos: Position) -> Option<&'a mut T> {
161
+
self.data
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+
.get_mut(pos.y as usize)
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+
.and_then(|row| row.get_mut(pos.x as usize))
164
+
}
165
+
159
166
/// Get a value from the grid at the given position,
160
167
/// panicking if the position is out of bounds.
161
168
///
+2
-2
years/2025/src/day_2.rs
+2
-2
years/2025/src/day_2.rs
···
28
28
.flat_map(|r| {
29
29
r.into_iter().filter(|x| {
30
30
let digs = num_digits(*x);
31
-
(2..=digs).into_iter().filter(|n| digs % n == 0).any(|n| {
31
+
(2..=digs).filter(|n| digs.is_multiple_of(*n)).any(|n| {
32
32
let mut parts = Vec::with_capacity(n);
33
33
let mut current = *x;
34
34
let split_at = digs / n;
···
40
40
parts
41
41
.first()
42
42
.copied()
43
-
.map_or(false, |first| parts.into_iter().all(|x| x == first))
43
+
.is_some_and(|first| parts.into_iter().all(|x| x == first))
44
44
})
45
45
})
46
46
})
+54
-6
years/2025/src/day_4.rs
+54
-6
years/2025/src/day_4.rs
···
1
-
2
1
use advent_core::{Day, day_stuff, ex_for_day};
2
+
use utils::{dir::ALL_8, tiles};
3
3
4
4
pub struct Day4;
5
5
6
+
tiles!(Tile, [
7
+
'@' => Paper,
8
+
'.' => Empty
9
+
]);
10
+
11
+
type Grid = utils::grid::Grid<Tile>;
12
+
6
13
impl Day for Day4 {
14
+
day_stuff!(4, "13", "43", Grid);
7
15
8
-
day_stuff!(4, "", "");
16
+
fn part_1(input: Self::Input) -> Option<String> {
17
+
let ans = input
18
+
.iter()
19
+
.filter(|(_, t)| **t == Tile::Paper)
20
+
.filter(|(pos, _)| {
21
+
input
22
+
.relatives(*pos, &ALL_8)
23
+
.filter(|(_, _, t)| **t == Tile::Paper)
24
+
.count()
25
+
< 4
26
+
})
27
+
.count();
9
28
10
-
fn part_1(_input: Self::Input) -> Option<String> {
11
-
None
29
+
Some(ans.to_string())
12
30
}
13
31
14
-
fn part_2(_input: Self::Input) -> Option<String> {
15
-
None
32
+
fn part_2(mut input: Self::Input) -> Option<String> {
33
+
let mut i = 0;
34
+
35
+
loop {
36
+
let next = input
37
+
.iter()
38
+
.filter(|(_, t)| **t == Tile::Paper)
39
+
.filter(|(pos, _)| {
40
+
input
41
+
.relatives(*pos, &ALL_8)
42
+
.filter(|(_, _, t)| **t == Tile::Paper)
43
+
.count()
44
+
< 4
45
+
})
46
+
.map(|(p, _)| p)
47
+
.collect::<Vec<_>>();
48
+
49
+
if next.is_empty() {
50
+
break;
51
+
} else {
52
+
i += next.len();
53
+
for pos in next {
54
+
*(input.get_mut(pos).unwrap()) = Tile::Empty;
55
+
}
56
+
}
57
+
}
58
+
59
+
Some(i.to_string())
60
+
}
61
+
62
+
fn parse_input(input: &str) -> Self::Input {
63
+
Grid::parse(input)
16
64
}
17
65
}
+10
years/2025/src/examples/day_4/1.txt
+10
years/2025/src/examples/day_4/1.txt