solved day 11

Author: devzero

day11/Cargo.lock

@@ -0,0 +1,8 @@
+[package]
+name = "day11"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day11/Cargo.toml

@@ -0,0 +1,10 @@
+3322874652
+5636588857
+7755117548
+5854121833
+2856682477
+3124873812
+1541372254
+8634383236
+2424323348
+2265635842

day11/input

@@ -0,0 +1,115 @@
+type Board = [u8; 100];
+
+fn parse(fname: &str) -> Board {
+    std::fs::read_to_string(fname)
+        .unwrap()
+        .lines()
+        .map(|l| {
+            l.chars()
+                .map(|c| c.to_digit(10).unwrap() as u8)
+                .collect::<Vec<u8>>()
+        })
+        .flatten()
+        .collect::<Vec<u8>>()
+        .try_into()
+        .unwrap()
+}
+
+fn adjacents(i: usize) -> Vec<usize> {
+    let x = i % 10;
+    let y = i / 10;
+    let mut adjs = Vec::new();
+    if (y > 0) && (x > 0) {
+        adjs.push(i - 11);
+    }
+    if y > 0 {
+        adjs.push(i - 10);
+    }
+    if (y > 0) && (x < 9) {
+        adjs.push(i - 9)
+    }
+    if x > 0 {
+        adjs.push(i - 1);
+    }
+    if x < 9 {
+        adjs.push(i + 1);
+    }
+    if (y < 9) && (x > 0) {
+        adjs.push(i + 9);
+    }
+    if y < 9 {
+        adjs.push(i + 10);
+    }
+    if (y < 9) && (x < 9) {
+        adjs.push(i + 11);
+    }
+    adjs
+}
+
+fn step(b: Board) -> (Board, Vec<usize>) {
+    let mut flashes = Vec::new();
+    let mut next = [0u8; 100];
+    for i in 0..100 {
+        next[i] = b[i] + 1;
+    }
+    while next
+        .iter()
+        .enumerate()
+        .any(|(i, &x)| (x > 9) && (!flashes.contains(&i)))
+    {
+        for (i, x) in next.into_iter().enumerate() {
+            if (x > 9) && !flashes.contains(&i) {
+                for j in adjacents(i) {
+                    next[j] += 1;
+                }
+                flashes.push(i);
+            }
+        }
+    }
+
+    for (i, x) in next.into_iter().enumerate() {
+        if x > 9 {
+            next[i] = 0;
+        }
+    }
+    (next, flashes)
+}
+
+fn part1(b: Board) -> usize {
+    let mut board = b;
+    let mut seen_flashes = 0;
+    for _ in 0..100 {
+        let (x, flashes) = step(board);
+        seen_flashes += flashes.len();
+        board = x;
+    }
+    seen_flashes
+}
+
+fn part2(b: Board) -> usize {
+    let mut steps = 0;
+    let mut flashes_this_step = 0;
+    let mut board = b;
+    while flashes_this_step < 100 {
+        let (x, flashes) = step(board);
+        flashes_this_step = flashes.len();
+        board = x;
+        steps += 1;
+    }
+    steps
+}
+
+#[test]
+fn test_part1() {
+    assert_eq!(part1(parse("test0")), 1656)
+}
+
+#[test]
+fn test_part2() {
+    assert_eq!(part2(parse("test0")), 195)
+}
+
+fn main() {
+    println!("{:?}", part1(parse("input")));
+    println!("{:?}", part2(parse("input")));
+}

day11/src/main.rs

@@ -0,0 +1,10 @@
+5483143223
+2745854711
+5264556173
+6141336146
+6357385478
+4167524645
+2176841721
+6882881134
+4846848554
+5283751526