solve: day19

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",
+    "aoc_derive", "day1", "day2", "day3", "day4", "day5", "day6", "day7", "day8", "day9", "day10", "day11", "day12", "day13", "day14", "day15", "day16", "day17", "day18", "day19",
 ]
 
 [workspace.dependencies]

day19/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "day19"
+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

day19/src/main.rs

@@ -0,0 +1,66 @@
+use std::collections::HashMap;
+
+use aoc_derive::aoc_main;
+use itertools::Itertools;
+use utils::*;
+
+fn part1<'a>(patterns: &[&'a str], target: &'a str) -> bool {
+    patterns.iter().any(|pattern| match target.strip_prefix(pattern) {
+        Some("") => true,
+        Some(target) => part1(patterns, target),
+        None => false,
+    })
+}
+
+fn part2<'a>(patterns: &[&'a str], target: &'a str, cache: &mut HashMap<&'a str, usize>) -> usize {
+    cache.get(&target).copied().unwrap_or_else(|| {
+        let res = patterns
+            .iter()
+            .map(|&pattern| match target.strip_prefix(pattern) {
+                Some("") => 1,
+                Some(target) => part2(patterns, target, cache),
+                None => 0,
+            })
+            .sum();
+        cache.insert(target, res);
+        res
+    })
+}
+
+#[aoc_main]
+fn solve(input: Input) -> impl Into<Solution> {
+    let (patterns, designs) = input.blocks().collect_tuple().unwrap();
+
+    let patterns = patterns.split(", ").collect_vec();
+    let designs = designs.lines().collect_vec();
+
+    let part1 = designs.iter().filter(|design| part1(&patterns, design)).count();
+
+    let part2 =
+        designs.iter().map(|design| part2(&patterns, design, &mut HashMap::new())).sum_usize();
+
+    (part1, part2)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_examples() {
+        use utils::assert_example;
+        assert_example!(
+            r#"r, wr, b, g, bwu, rb, gb, br
+
+brwrr
+bggr
+gbbr
+rrbgbr
+ubwu
+bwurrg
+brgr
+bbrgwb"#,
+            6,
+            16
+        );
+    }
+}