Day 19 solutions

Author: Cadiac

README.md

@@ -104,3 +104,4 @@ This should start the server at `localhost:8080`.
 ❄️ [Day 16](aoc-solver/src/y2024/day16.rs)
 ❄️ [Day 17](aoc-solver/src/y2024/day17.rs)
 ❄️ [Day 18](aoc-solver/src/y2024/day18.rs)
+❄️ [Day 19](aoc-solver/src/y2024/day19.rs)

aoc-solver/src/y2024/day19.rs

@@ -0,0 +1,111 @@
+use std::collections::HashMap;
+
+use crate::solution::{AocError, Solution};
+
+fn parse(input: &str) -> Result<(Vec<String>, Vec<String>), AocError> {
+    let (towels, designs) = input
+        .split_once("\n\n")
+        .ok_or_else(|| AocError::parse(input, "Missing towel and designs sections"))?;
+
+    let towels: Vec<String> = towels.split(", ").map(|towel| towel.to_owned()).collect();
+    let designs: Vec<String> = designs.lines().map(|towel| towel.to_owned()).collect();
+
+    Ok((towels, designs))
+}
+
+fn count_possible(towels: &[String], design: &str, cache: &mut HashMap<String, usize>) -> usize {
+    if design.is_empty() {
+        return 1;
+    }
+
+    if let Some(&count) = cache.get(design) {
+        return count;
+    }
+
+    let possible = towels
+        .iter()
+        .filter_map(|towel| design.strip_suffix(towel))
+        .map(|remaining| count_possible(towels, remaining, cache))
+        .sum();
+
+    cache.insert(design.to_owned(), possible);
+
+    possible
+}
+
+pub struct Day19;
+impl Solution for Day19 {
+    type A = usize;
+    type B = usize;
+
+    fn default_input(&self) -> &'static str {
+        include_str!("../../../inputs/2024/day19.txt")
+    }
+
+    fn part_1(&self, input: &str) -> Result<usize, AocError> {
+        let (towels, designs) = parse(input)?;
+
+        let mut cache = HashMap::new();
+        let possible = designs
+            .iter()
+            .filter(|design| count_possible(&towels, design, &mut cache) > 0)
+            .count();
+
+        Ok(possible)
+    }
+
+    fn part_2(&self, input: &str) -> Result<usize, AocError> {
+        let (towels, designs) = parse(input)?;
+
+        let mut cache = HashMap::new();
+        let possible = designs
+            .iter()
+            .map(|design| count_possible(&towels, design, &mut cache))
+            .sum();
+
+        Ok(possible)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_solves_part1_example() {
+        assert_eq!(
+            Day19.part_1(
+                "r, wr, b, g, bwu, rb, gb, br\n\
+                 \n\
+                 brwrr\n\
+                 bggr\n\
+                 gbbr\n\
+                 rrbgbr\n\
+                 ubwu\n\
+                 bwurrg\n\
+                 brgr\n\
+                 bbrgwb"
+            ),
+            Ok(6)
+        );
+    }
+
+    #[test]
+    fn it_solves_part2_example() {
+        assert_eq!(
+            Day19.part_2(
+                "r, wr, b, g, bwu, rb, gb, br\n\
+                 \n\
+                 brwrr\n\
+                 bggr\n\
+                 gbbr\n\
+                 rrbgbr\n\
+                 ubwu\n\
+                 bwurrg\n\
+                 brgr\n\
+                 bbrgwb"
+            ),
+            Ok(16)
+        );
+    }
+}

aoc-solver/src/y2024/mod.rs

@@ -18,15 +18,15 @@ pub mod day15;
 pub mod day16;
 pub mod day17;
 pub mod day18;
-// pub mod day19;
+pub mod day19;
 // pub mod day20;
 // pub mod day21;
 // pub mod day22;
 // pub mod day23;
 // pub mod day24;
 // pub mod day25;
 
-pub const MAX_DAYS: u8 = 18;
+pub const MAX_DAYS: u8 = 19;
 
 pub struct Y2024;
 
@@ -51,7 +51,7 @@ impl Solver for Y2024 {
             16 => day16::Day16.run(input, 16, 2024),
             17 => day17::Day17.run(input, 17, 2024),
             18 => day18::Day18.run(input, 18, 2024),
-            // 19 => day19::Day19.run(input, 19, 2024),
+            19 => day19::Day19.run(input, 19, 2024),
             // 20 => day20::Day20.run(input, 20, 2024),
             // 21 => day21::Day21.run(input, 21, 2024),
             // 22 => day22::Day22.run(input, 22, 2024),
@@ -93,7 +93,7 @@ impl Solver for Y2024 {
             16 => include_str!("./day16.rs"),
             17 => include_str!("./day17.rs"),
             18 => include_str!("./day18.rs"),
-            // 19 => include_str!("./day19.rs"),
+            19 => include_str!("./day19.rs"),
             // 20 => include_str!("./day20.rs"),
             // 21 => include_str!("./day21.rs"),
             // 22 => include_str!("./day22.rs"),

aoc-web/src/header.rs

@@ -39,6 +39,7 @@ pub fn header(props: &HeaderProps) -> Html {
                                     <NavLink route={Route::Solution { year: 2024, day: 16 }} current={props.route.clone()} text={"16"}/>
                                     <NavLink route={Route::Solution { year: 2024, day: 17 }} current={props.route.clone()} text={"17"}/>
                                     <NavLink route={Route::Solution { year: 2024, day: 18 }} current={props.route.clone()} text={"18"}/>
+                                    <NavLink route={Route::Solution { year: 2024, day: 19 }} current={props.route.clone()} text={"19"}/>
                                 </>
                             }
                         },