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add neighbour and cardinal iterators to grid

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This commit is contained in:
Keenan Tims
2025-12-04 15:49:37 -08:00
parent 2d9abb841b
commit faa452149a
2 changed files with 127 additions and 26 deletions
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5
src/day4.rs
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@@ -10,11 +10,10 @@ fn parse(input: &str) -> Grid<u8> {
fn part1(input: &Grid<u8>) -> u64 {
(0..input.height() * input.width())
.filter(|i| *input.get(&input.coord(*i as i64).unwrap()).unwrap() == b'@')
.map(|i| input.neighbours_count(input.coord(i as i64).unwrap(), |c| *c == b'@'))
.map(|i| input.neighbours_count(&input.coord(i as i64).unwrap(), |c| *c == b'@'))
.filter(|n| *n < 4)
.count() as u64
}
#[aoc(day4, part2)]
fn part2(input: &Grid<u8>) -> u64 {
let mut grid = input.clone();
@@ -25,7 +24,7 @@ fn part2(input: &Grid<u8>) -> u64 {
for i in 0..grid.width() * grid.height() {
let pos = grid.coord(i as i64).unwrap();
if grid.get(&pos).is_some_and(|c| *c == b'@')
&& grid.neighbours_count(pos, |c| *c == b'@') < 4
&& grid.neighbours_count(&pos, |c| *c == b'@') < 4
{
// remove the roll
grid.set(&pos, b'.');