From 000001502271adcc13d5ba3fee615c92a5ea1c33 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matej=20Jane=C5=BEi=C4=8D?= <janezic.mj@gmail.com>
Date: Wed, 11 Dec 2024 06:37:27 +0100
Subject: [PATCH] solution: day 11

---
 data/examples/11.txt |  1 +
 src/bin/11.rs        | 72 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)
 create mode 100644 data/examples/11.txt
 create mode 100644 src/bin/11.rs

diff --git a/data/examples/11.txt b/data/examples/11.txt
new file mode 100644
index 000000000..9b26c84
--- /dev/null
+++ b/data/examples/11.txt
@@ -0,0 +1 @@
+125 17
diff --git a/src/bin/11.rs b/src/bin/11.rs
new file mode 100644
index 000000000..1422a97
--- /dev/null
+++ b/src/bin/11.rs
@@ -0,0 +1,72 @@
+use std::mem::swap;
+
+use hashbrown::HashMap;
+use itertools::Itertools;
+
+fn blink(map: &HashMap<usize, usize>, nmap: &mut HashMap<usize, usize>) {
+    for (&k, &v) in map.iter() {
+        match k {
+            0 => *nmap.entry(1).or_default() += v,
+            x if (x.ilog10() + 1) % 2 == 0 => {
+                let xlen = x.ilog10() + 1;
+                let xhalf = 10_usize.pow(xlen / 2);
+
+                *nmap.entry(x / xhalf).or_default() += v;
+                *nmap.entry(x % xhalf).or_default() += v;
+            }
+            x => *nmap.entry(x * 2024).or_default() += v,
+        }
+    }
+}
+
+fn solve(input: &str, blinks: usize) -> usize {
+    let v = input
+        .split(" ")
+        .filter_map(|x| x.parse().ok())
+        .collect_vec();
+
+    let mut map = HashMap::<usize, usize>::new();
+
+    for vv in v {
+        *map.entry(vv).or_default() += 1;
+    }
+
+    let mut nmap = HashMap::<usize, usize>::new();
+
+    for _ in 0..blinks {
+        blink(&map, &mut nmap);
+        map.clear();
+        swap(&mut map, &mut nmap);
+    }
+
+    map.values().sum()
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    solve(input, 25).into()
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    solve(input, 75).into()
+}
+
+aoc::solution!(11);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(
+            part_one(&aoc::template::read_file("examples", 11)),
+            Some(55312)
+        );
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(
+            part_two(&aoc::template::read_file("examples", 11)),
+            Some(65601038650482)
+        );
+    }
+}