From 0d8abe63863f2f1e376b0e5fd1d2ef09ef69cd5b Mon Sep 17 00:00:00 2001
From: Himangshu Saikia <himangshu.saikia.iitg@gmail.com>
Date: Thu, 19 Dec 2024 06:22:58 +0100
Subject: [PATCH] 2024_19

---
 src/bin/2024_19/main.rs | 84 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 src/bin/2024_19/main.rs

diff --git a/src/bin/2024_19/main.rs b/src/bin/2024_19/main.rs
new file mode 100644
index 0000000..07621f8
--- /dev/null
+++ b/src/bin/2024_19/main.rs
@@ -0,0 +1,84 @@
+use std::collections::HashMap;
+
+use aoc::{common, io};
+
+fn possible_ways(patterns: &[&str], towel: &str, map: &mut HashMap<String, usize>) -> usize {
+    if towel.is_empty() {
+        return 1;
+    }
+    if map.get(towel).is_some() {
+        return *map.get(towel).unwrap();
+    }
+    let mut ways = 0;
+    for p in patterns.iter() {
+        if p.len() > towel.len() {
+            continue;
+        }
+        if **p == towel[0..p.len()] {
+            ways += possible_ways(patterns, &towel[p.len()..], map);
+        }
+    }
+    map.insert(towel.to_string(), ways);
+    ways
+}
+
+fn possible(patterns: &[&str], towel: &str, map: &mut HashMap<String, bool>) -> bool {
+    if towel.is_empty() {
+        return true;
+    }
+    if map.get(towel).is_some() {
+        return *map.get(towel).unwrap();
+    }
+    let mut status = false;
+    for p in patterns.iter() {
+        if p.len() > towel.len() {
+            continue;
+        }
+        if **p == towel[0..p.len()] {
+            status |= possible(patterns, &towel[p.len()..], map);
+        }
+    }
+    map.insert(towel.to_string(), status);
+    status
+}
+
+fn solve<const PART: usize>(input: &str) -> usize {
+    let mut ans = 0;
+    let batches = io::line_batches(input);
+    let patterns = io::tokenize(batches[0][0], ", ");
+    //println!("{:?}", patterns);
+
+    let mut cache: HashMap<String, bool> = HashMap::new();
+    let mut cache2: HashMap<String, usize> = HashMap::new();
+
+    for towel in batches[1].iter() {
+        //println!("Checking {}", towel);
+        if PART == 1 && possible(&patterns, towel, &mut cache) {
+            ans += 1;
+        }
+        if PART == 2 {
+            ans += possible_ways(&patterns, towel, &mut cache2);
+        }
+    }
+    ans
+}
+
+fn main() {
+    let input = common::get_input();
+    println!("{input:?}");
+    common::timed(&input, solve::<1>, true);
+    common::timed(&input, solve::<2>, false);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_samples() {
+        let sample_input =
+            "r, wr, b, g, bwu, rb, gb, br\n\nbrwrr\nbggr\ngbbr\nrrbgbr\nubwu\nbwurrg\nbrgr\nbbrgwb";
+        assert_eq!(solve::<1>(sample_input), 6);
+        assert_eq!(solve::<2>(sample_input), 16);
+    }
+}