Part 1

2024/rust/src/day11.rs

@@ -0,0 +1,56 @@
+mod prelude;
+pub use crate::prelude::*;
+
+fn main() {
+    let input = day_input(11);
+    show_answers(part1(&input), part2(&input));
+}
+
+fn part1(input: &str) -> usize {
+    stone_blinks(input, 25)
+}
+
+fn stone_blinks(input: &str, count: usize) -> usize {
+    let mut stones: Vec<usize> = input
+        .trim()
+        .split(" ")
+        .map(|s| s.parse().unwrap())
+        .collect();
+    let mut next_stones = vec![];
+    for blink in 0..count {
+        println!("{blink} {}", stones.len());
+        for (_i, s) in stones.iter().enumerate() {
+            // next_stones.push(*s)
+            if *s == 0 {
+                next_stones.push(1);
+                continue;
+            }
+            let ss = s.to_string();
+            if ss.len() % 2 == 0 {
+                let mid = ss.len() / 2;
+                let (s1, s2) = (ss[0..mid].parse().unwrap(), ss[mid..].parse().unwrap());
+                next_stones.push(s1);
+                next_stones.push(s2);
+                continue;
+            }
+            next_stones.push(s * 2024)
+        }
+        stones = next_stones;
+        next_stones = vec![];
+    }
+    stones.len()
+}
+
+fn part2(input: &str) -> usize {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = r#"125 17"#;
+        assert_eq!(part1(input), 55312);
+        assert_eq!(part2(input), 0);
+    }
+}