add: day 11, stub of day12

src/bin/d11p1.rs

@@ -0,0 +1,82 @@
+use std::collections::{HashMap, HashSet, VecDeque};
+
+use advent_of_code_2024::{add_pair, make_main, mul_pair, next, nexti64, Pair, SResult};
+
+make_main!();
+
+fn solve(lines: Vec<String>) -> SResult<(usize, usize)> {
+    assert_eq!(1, lines.len());
+    let state: Vec<usize> = lines[0]
+        .split_ascii_whitespace()
+        .map(|c| c.parse::<usize>().unwrap())
+        .collect();
+
+    let mut total = 0;
+    for digit in state.iter() {
+        total += one(vec!(*digit), 75);
+    }
+
+    Ok((one(state, 25), total))
+}
+
+fn one(vstate: Vec<usize>, reps: usize) -> usize {
+    let mut state: HashMap<usize, usize> = HashMap::default();
+    for n in vstate {
+        *state.entry(n).or_insert(0) += 1;
+    }
+    for _ in 0..reps {
+        let mut next: HashMap<usize, usize> = HashMap::with_capacity(state.len());
+        for (key, count) in state.into_iter() {
+            if key == 0 {
+                *next.entry(1).or_insert(0) += count;
+            } else if digit_count(key) % 2 == 0 {
+                let new_digits = split(key);
+                *next.entry(new_digits.0).or_insert(0) += count;
+                *next.entry(new_digits.1).or_insert(0) += count;
+            } else {
+
+                *next.entry(key*2024).or_insert(0) += count;
+            }
+        }
+
+        state = next;
+    }
+
+    state.iter().map(|a| a.1).sum()
+
+}
+
+fn digit_count(mut n: usize) -> usize {
+    let mut count = 0;
+    while n > 0 {
+        count += 1;
+        n /= 10;
+    }
+    count
+}
+
+fn split(mut n: usize) -> (usize, usize) {
+    let size = digit_count(n);
+    let mut a = 0;
+    let mut off = 1;
+    for _ in 0..size/2 {
+        a += (n % 10) * off;
+        off *= 10;
+        n /= 10;
+    }
+    (n, a)
+}
+
+
+#[cfg(test)]
+mod tests {
+    use advent_of_code_2024::input;
+
+    use super::*;
+    #[test]
+    fn sample_input() {
+        let strings: Vec<String> = input!("d11p1.txt");
+        let got = solve(strings).unwrap();
+        assert_eq!(got, (55312, 65601038650482));
+    }
+}