Add day11

Cargo.toml

@@ -6,4 +6,5 @@ edition = "2021"
 [dependencies]
 aoc-runner = "0.3.0"
 aoc-runner-derive = "0.3.0"
+memoize = "0.4.2"
 regex = "1.11.1"

input/2024/day11.txt

@@ -0,0 +1 @@
+4329 385 0 1444386 600463 19 1 56615

src/day11.rs

@@ -0,0 +1,101 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+use memoize::memoize;
+
+#[aoc_generator(day11)]
+pub fn input_generator(input: &str) -> Vec<usize> {
+    input.split(" ").map(|s| s.parse().unwrap()).collect()
+}
+
+#[memoize]
+pub fn blink(stone: usize, counter: usize, limit: usize) -> usize {
+    let mut stack = 0;
+    if counter == limit {
+        return 1;
+    }
+
+    if stone == 0 {
+        stack += blink(1, counter + 1, limit);
+    } else {
+        let mut div = stone;
+        let mut count = 0;
+        while div > 0 {
+            div /= 10;
+            count += 1;
+        }
+        if count % 2 == 0 {
+            stack += blink(stone / 10_usize.pow(count / 2), counter + 1, limit);
+            stack += blink(stone % 10_usize.pow(count / 2), counter + 1, limit);
+        } else {
+            stack += blink(stone * 2024, counter + 1, limit);
+        }
+    }
+    stack
+}
+
+#[aoc(day11, part1)]
+pub fn part1(input: &[usize]) -> usize {
+    let mut lenght = 0;
+    for stone in input {
+        lenght += blink(*stone, 0, 25);
+    }
+    lenght
+}
+
+#[aoc(day11, part2)]
+pub fn part2(input: &[usize]) -> usize {
+    let mut lenght = 0;
+    for stone in input {
+        lenght += blink(*stone, 0, 75);
+    }
+    lenght
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT: &str = "125 17";
+
+    #[test]
+    fn test_part1() {
+        assert_eq!(55312, part1(&input_generator(INPUT)))
+    }
+
+    #[test]
+    fn test_part2() {
+        assert_eq!(55312, part2(&input_generator(INPUT)))
+    }
+}
+
+// First implementation: too slow and no memoization possible.
+
+// pub fn blink(stones: Vec<usize>, counter: usize, limit: usize) -> Vec<usize> {
+//     if counter == limit {
+//         return stones;
+//     }
+//     let stones = stones.iter().fold(vec![], |mut acc, stone| {
+//         if *stone == 0 {
+//             acc.push(1);
+//             return acc;
+//         }
+//         let mut div = *stone;
+//         let mut count = 0;
+//         while div > 0 {
+//             div /= 10;
+//             count += 1;
+//         }
+//         if count % 2 == 0 {
+//             acc.push(*stone / 10_usize.pow(count / 2));
+//             acc.push(*stone % 10_usize.pow(count / 2));
+//             return acc;
+//         }
+//         acc.push(2024 * *stone);
+//         acc
+//     });
+//     blink(stones, counter + 1, limit)
+// }
+
+// #[aoc(day11, part1)]
+// pub fn part1(input: &[usize]) -> usize {
+//     blink(input.to_vec(), 0, 25).len()
+// }

src/lib.rs

@@ -1,12 +1,12 @@
 use aoc_runner_derive::aoc_lib;
 
 mod day1;
+mod day11;
 mod day2;
 mod day3;
 mod day4;
 mod day5;
 mod day6;
 mod day7;
-mod day8;
 
 aoc_lib! { year = 2024 }