solve: day25

Author: tom-anders

Cargo.toml

@@ -2,7 +2,7 @@
 resolver = "2"
 members = [
     "utils",
-    "aoc_derive", "day1", "day2", "day3", "day4", "day5", "day6", "day7", "day8", "day9", "day10", "day11", "day12", "day13", "day14", "day15", "day16", "day17", "day18", "day19", "day20", "day21", "day22", "day23", "day24",
+    "aoc_derive", "day1", "day2", "day3", "day4", "day5", "day6", "day7", "day8", "day9", "day10", "day11", "day12", "day13", "day14", "day15", "day16", "day17", "day18", "day19", "day20", "day21", "day22", "day23", "day24", "day25",
 ]
 
 [workspace.dependencies]

day25/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "day25"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+aoc_derive.path = '../aoc_derive'
+utils.path = '../utils'
+derive_more.workspace = true
+itertools.workspace = true
+lazy-regex.workspace = true
+parse-display.workspace = true
+rayon.workspace = true
+regex.workspace = true
+num.workspace = true
+
+[dev-dependencies]
+pretty_assertions.workspace = true

day25/src/main.rs

@@ -0,0 +1,73 @@
+use aoc_derive::aoc_main;
+use grid::Grid;
+use itertools::iproduct;
+use utils::*;
+
+#[aoc_main]
+fn solve(input: Input) -> impl Into<Solution> {
+    let (locks, keys): (Vec<_>, Vec<_>) = input
+        .blocks()
+        .map(|block| Grid::<char>::from_iter(block.lines().map(|l| l.chars())))
+        .partition(|grid| grid.row(0).all(|(_, &c)| c == '#'));
+
+    iproduct!(locks, keys)
+        .filter(|(lock, key)| {
+            lock.cols().zip(key.cols()).all(|(lhs, rhs)| {
+                lhs.values().filter(|&&c| c == '#').count()
+                    + rhs.values().filter(|&&c| c == '#').count()
+                    <= 7
+            })
+        })
+        .count()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_examples() {
+        use utils::assert_example;
+        assert_example!(
+            r#"#####
+.####
+.####
+.####
+.#.#.
+.#...
+.....
+
+#####
+##.##
+.#.##
+...##
+...#.
+...#.
+.....
+
+.....
+#....
+#....
+#...#
+#.#.#
+#.###
+#####
+
+.....
+.....
+#.#..
+###..
+###.#
+###.#
+#####
+
+.....
+.....
+.....
+#....
+#.#..
+#.#.#
+#####"#,
+            3
+        );
+    }
+}

utils/src/grid.rs

@@ -254,6 +254,10 @@ impl<'a, T> ColIter<'a, T> {
     fn new(grid: &'a Grid<T>, col: usize) -> Self {
         ColIter { grid, row: 0, row_back: grid.num_rows(), col }
     }
+
+    pub fn values(self) -> impl Iterator<Item = &'a T> {
+        self.map(|(_, val)| val)
+    }
 }
 
 impl<'a, T> Iterator for ColIter<'a, T> {