Added day 12 solutions

src/day12/1.rs

@@ -0,0 +1,108 @@
+#![feature(test)]
+
+use std::collections::VecDeque;
+extern crate test;
+
+const INPUTS: [&[u8]; 2] = [
+    include_bytes!("./sample.txt"),
+    include_bytes!("./input.txt"),
+];
+
+struct Grid<const M: usize, const N: usize> {
+    grid: [[u8; N]; M],
+    start: (usize, usize),
+    end: (usize, usize),
+}
+
+fn parse<const M: usize, const N: usize>(input: &[u8]) -> Grid<M, N> {
+    let mut out = [[0; N]; M];
+    let mut start = (0, 0);
+    let mut end = (0, 0);
+
+    for (i, row) in input.split(|&c| c == b'\n').enumerate() {
+        for (j, v) in row.iter().enumerate() {
+            out[i][j] = match *v {
+                b'E' => {
+                    end = (i, j);
+                    b'z'
+                }
+                b'S' => {
+                    start = (i, j);
+                    b'a'
+                }
+                v => v,
+            };
+        }
+    }
+
+    Grid {
+        grid: out,
+        start,
+        end,
+    }
+}
+
+fn main() {
+    let output = parse::<5, 8>(INPUTS[0]);
+    let score = solution::<5, 8>(output);
+    println!("{}", score);
+    let output = parse::<41, 61>(INPUTS[1]);
+    let score = solution::<41, 61>(output);
+    println!("{}", score);
+}
+
+fn solution<const M: usize, const N: usize>(input: Grid<M, N>) -> usize {
+    let mut q = VecDeque::with_capacity(500);
+    q.push_back((input.start.0, input.start.1, 0));
+
+    let mut visited = [[false; N]; M];
+
+    while !q.is_empty() {
+        let l = q.len();
+
+        for _ in 0..l {
+            let next = q.pop_front().unwrap();
+            let cheight = input.grid[next.0][next.1];
+
+            if next.0 == input.end.0 && next.1 == input.end.1 {
+                return next.2;
+            }
+
+            if visited[next.0][next.1] {
+                continue;
+            }
+            visited[next.0][next.1] = true;
+
+            for (x, y) in [(-1, 0), (1, 0), (0, -1), (0, 1)] {
+                let i = next.0 as i32 + x;
+                let j = next.1 as i32 + y;
+
+                if i < 0
+                    || j < 0
+                    || i >= M as i32
+                    || j >= N as i32
+                    || visited[i as usize][j as usize]
+                {
+                    continue;
+                }
+
+                let nheight = input.grid[i as usize][j as usize];
+
+                if nheight - cheight <= 1 || nheight <= cheight {
+                    q.push_back((i as usize, j as usize, next.2 + 1))
+                }
+            }
+        }
+    }
+
+    0
+}
+
+#[bench]
+fn solution_bench(b: &mut test::Bencher) {
+    b.iter(|| {
+        let input = parse::<41, 61>(INPUTS[1]);
+        let result = solution(input);
+        test::black_box(result);
+    })
+}

src/day12/2.rs

@@ -0,0 +1,107 @@
+#![feature(test)]
+
+use std::collections::VecDeque;
+extern crate test;
+
+const INPUTS: [&[u8]; 2] = [
+    include_bytes!("./sample.txt"),
+    include_bytes!("./input.txt"),
+];
+
+struct Grid<const M: usize, const N: usize> {
+    grid: [[u8; N]; M],
+    end: (usize, usize),
+}
+
+fn parse<const M: usize, const N: usize>(input: &[u8]) -> Grid<M, N> {
+    let mut out = [[0; N]; M];
+    let mut end = (0, 0);
+
+    for (i, row) in input.split(|&c| c == b'\n').enumerate() {
+        for (j, v) in row.iter().enumerate() {
+            out[i][j] = match *v {
+                b'E' => {
+                    end = (i, j);
+                    b'z'
+                }
+                b'S' => b'a',
+                v => v,
+            };
+        }
+    }
+
+    Grid { grid: out, end }
+}
+
+fn main() {
+    let output = parse::<5, 8>(INPUTS[0]);
+    let score = solution::<5, 8>(output);
+    println!("{}", score);
+    let output = parse::<41, 61>(INPUTS[1]);
+    let score = solution::<41, 61>(output);
+    println!("{}", score);
+}
+
+fn solution<const M: usize, const N: usize>(input: Grid<M, N>) -> usize {
+    // Find a path from b'E' to the closest b'a'
+    bfs::<M, N>(&input.grid, (input.end.0, input.end.1, 0))
+}
+
+fn bfs<const M: usize, const N: usize>(
+    input: &[[u8; N]; M],
+    start: (usize, usize, usize),
+) -> usize {
+    let mut q = VecDeque::with_capacity(500);
+    q.push_back(start);
+
+    let mut visited = [[false; N]; M];
+
+    while !q.is_empty() {
+        let l = q.len();
+
+        for _ in 0..l {
+            let next = q.pop_front().unwrap();
+            let cheight = input[next.0][next.1];
+
+            if cheight == b'a' {
+                return next.2;
+            }
+
+            if visited[next.0][next.1] {
+                continue;
+            }
+            visited[next.0][next.1] = true;
+
+            for (x, y) in [(-1, 0), (1, 0), (0, -1), (0, 1)] {
+                let i = next.0 as i32 + x;
+                let j = next.1 as i32 + y;
+
+                if i < 0
+                    || j < 0
+                    || i >= M as i32
+                    || j >= N as i32
+                    || visited[i as usize][j as usize]
+                {
+                    continue;
+                }
+
+                let nheight = input[i as usize][j as usize];
+
+                if cheight - nheight <= 1 || cheight <= nheight {
+                    q.push_back((i as usize, j as usize, next.2 + 1))
+                }
+            }
+        }
+    }
+
+    std::usize::MAX
+}
+
+#[bench]
+fn solution_bench(b: &mut test::Bencher) {
+    b.iter(|| {
+        let input = parse::<41, 61>(INPUTS[1]);
+        let result = solution(input);
+        test::black_box(result);
+    })
+}

src/day12/input.txt

@@ -0,0 +1,41 @@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src/day12/sample.txt

@@ -0,0 +1,5 @@
+Sabqponm
+abcryxxl
+accszExk
+acctuvwj
+abdefghi