Day 25

Author: prevostc

README.md

@@ -35,8 +35,9 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 22](./src/bin/22.rs) | `624.7µs` | `8.1ms` |
 | [Day 23](./src/bin/23.rs) | `157.2µs` | `620.5µs` |
 | [Day 24](./src/bin/24.rs) | `61.8µs` | `16.9µs` |
+| [Day 25](./src/bin/25.rs) | `88.7µs` | `84.3µs` |
 
-**Total: 26.27ms**
+**Total: 26.45ms**
 <!--- benchmarking table --->
 
 ---

data/examples/25.txt

@@ -0,0 +1,39 @@
+#####
+.####
+.####
+.####
+.#.#.
+.#...
+.....
+
+#####
+##.##
+.#.##
+...##
+...#.
+...#.
+.....
+
+.....
+#....
+#....
+#...#
+#.#.#
+#.###
+#####
+
+.....
+.....
+#.#..
+###..
+###.#
+###.#
+#####
+
+.....
+.....
+.....
+#....
+#.#..
+#.#.#
+#####

src/bin/25.rs

@@ -0,0 +1,71 @@
+use itertools::Itertools;
+
+advent_of_code::solution!(25);
+
+const WIDTH: usize = 5;
+const HEIGHT: usize = 6;
+
+fn parse_input(input: &str) -> (Vec<[usize; WIDTH]>, Vec<[usize; WIDTH]>) {
+    let mut keys = Vec::new();
+    let mut padlocks = Vec::new();
+
+    for block in input.split("\n\n") {
+        let mut data = [0; WIDTH];
+        for line in block.lines().filter(|l| !l.is_empty()) {
+            for (i, c) in line.chars().enumerate() {
+                if c == '#' {
+                    data[i] += 1;
+                }
+            }
+        }
+        let is_padlock = block.lines().next().unwrap() == "#".repeat(WIDTH);
+
+        if is_padlock {
+            padlocks.push(data);
+        } else {
+            keys.push(data);
+        }
+    }
+
+    (keys, padlocks)
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let (keys, padlocks) = parse_input(input);
+
+    let overlaps = keys
+        .iter()
+        .cartesian_product(padlocks.iter())
+        .filter(|(&key, &padlock)| {
+            let overlap = key
+                .iter()
+                .zip(padlock.iter())
+                .any(|(k, p)| *k + *p > (HEIGHT + 1));
+
+            !overlap
+        })
+        .count();
+
+    Some(overlaps)
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    part_one(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(3));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(3));
+    }
+}