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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,94 @@ | ||
| #![feature(test)] | ||
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| use std::collections::VecDeque; | ||
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| use aoc::grid::Direction; | ||
| use itertools::Itertools; | ||
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| struct Input { | ||
| width: usize, | ||
| height: usize, | ||
| grid: Vec<usize>, | ||
| prefix_len: usize, | ||
| bytes: Vec<(usize, usize)>, | ||
| } | ||
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| fn setup(input: &str) -> Input { | ||
| let mut lines = input.trim().lines().peekable(); | ||
| let (width, height, prefix_len) = match lines.next_if(|l| l.starts_with('#')) { | ||
| Some(line) => line | ||
| .trim_start_matches('#') | ||
| .split_whitespace() | ||
| .map(|n| n.parse().unwrap()) | ||
| .collect_tuple() | ||
| .unwrap(), | ||
| None => (71, 71, 1024), | ||
| }; | ||
|
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| let bytes = lines | ||
| .map(|l| { | ||
| l.split(',') | ||
| .map(|n| n.parse().unwrap()) | ||
| .collect_tuple() | ||
| .unwrap() | ||
| }) | ||
| .collect::<Vec<_>>(); | ||
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| let mut grid = vec![usize::MAX; width * height]; | ||
| for (i, &(x, y)) in bytes.iter().enumerate() { | ||
| grid[y * width + x] = i; | ||
| } | ||
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| Input { | ||
| width, | ||
| height, | ||
| grid, | ||
| prefix_len, | ||
| bytes, | ||
| } | ||
| } | ||
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| fn bfs(input: &Input, prefix_len: usize) -> Option<usize> { | ||
| let mut queue = VecDeque::from([(0, 0, 0)]); | ||
| let mut visited = vec![false; input.width * input.height]; | ||
| while let Some((d, x, y)) = queue.pop_front() { | ||
| let idx = y * input.width + x; | ||
| if std::mem::replace(&mut visited[idx], true) { | ||
| continue; | ||
| } | ||
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| if (x, y) == (input.width - 1, input.height - 1) { | ||
| return Some(d); | ||
| } | ||
|
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| queue.extend( | ||
| Direction::iter() | ||
| .flat_map(|d| d.step(x, y, input.width, input.height)) | ||
| .filter(|&(nx, ny)| input.grid[ny * input.width + nx] >= prefix_len) | ||
| .map(|(nx, ny)| (d + 1, nx, ny)), | ||
| ); | ||
| } | ||
|
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| None | ||
| } | ||
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| fn part1(input: &Input) -> usize { | ||
| bfs(input, input.prefix_len).unwrap() | ||
| } | ||
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| fn part2(input: &Input) -> String { | ||
| let mut left = 0; | ||
| let mut right = input.bytes.len(); | ||
| while left + 1 < right { | ||
| let m = left.midpoint(right); | ||
| match bfs(input, m) { | ||
| Some(_) => left = m, | ||
| None => right = m, | ||
| } | ||
| } | ||
| debug_assert_eq!(left + 1, right); | ||
| let (x, y) = input.bytes[right - 1]; | ||
| format!("{x},{y}") | ||
| } | ||
|
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| aoc::main!(2024, 18, ex: 1); |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -16,7 +16,7 @@ aoc::year! { | |
| "15.rs", | ||
| "16.rs", | ||
| "17.rs", | ||
| // "18.rs", | ||
| "18.rs", | ||
| // "19.rs", | ||
| // "20.rs", | ||
| // "21.rs", | ||
|
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||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
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@@ -411,3 +411,6 @@ path = "2024/16.rs" | |
| [[bin]] | ||
| name = "2024_17" | ||
| path = "2024/17.rs" | ||
| [[bin]] | ||
| name = "2024_18" | ||
| path = "2024/18.rs" | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,26 @@ | ||
| # 7 7 12 | ||
| 5,4 | ||
| 4,2 | ||
| 4,5 | ||
| 3,0 | ||
| 2,1 | ||
| 6,3 | ||
| 2,4 | ||
| 1,5 | ||
| 0,6 | ||
| 3,3 | ||
| 2,6 | ||
| 5,1 | ||
| 1,2 | ||
| 5,5 | ||
| 2,5 | ||
| 6,5 | ||
| 1,4 | ||
| 0,4 | ||
| 6,4 | ||
| 1,1 | ||
| 6,1 | ||
| 1,0 | ||
| 0,5 | ||
| 1,6 | ||
| 2,0 |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1 @@ | ||
| 22 |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1 @@ | ||
| 6,1 |