From 9e25265af581a2afa49677281a4f656d0a60ab29 Mon Sep 17 00:00:00 2001
From: YK <yk@qcl.one>
Date: Thu, 12 Dec 2024 04:30:39 +0300
Subject: [PATCH] solution: day 11

mostly stolen..........................
---
 src/days.rs     |  2 +-
 src/days/d11.rs | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+), 1 deletion(-)
 create mode 100644 src/days/d11.rs

diff --git a/src/days.rs b/src/days.rs
index 7f0258a..1c4b09e 100644
--- a/src/days.rs
+++ b/src/days.rs
@@ -8,7 +8,7 @@ pub mod d7;
 pub mod d8;
 pub mod d9;
 pub mod d10;
-// pub mod d11;
+pub mod d11;
 // pub mod d12;
 // pub mod d13;
 // pub mod d14;
diff --git a/src/days/d11.rs b/src/days/d11.rs
new file mode 100644
index 0000000..2645fb5
--- /dev/null
+++ b/src/days/d11.rs
@@ -0,0 +1,84 @@
+use cached::proc_macro::cached;
+
+use crate::prelude::*;
+
+pub type I = Vec<u128>;
+pub type O = u128;
+
+fn _parse (data: &str) -> I {
+    data.trim().split_ascii_whitespace().map(|e| p!(e)).collect()
+}
+
+fn _solve (data: I, iterations: u32) -> O {
+    data.into_iter().map(|stone| count(stone, iterations)).sum()
+}
+
+fn count_digits (i: u128) -> u32 {
+    i.checked_ilog10().unwrap_or(0) + 1
+}
+
+#[cached]
+fn count (stone: u128, blinks: u32) -> u128 {
+    match blinks {
+        0 => 1,
+        _ => next(stone).into_iter().flatten().map(|stone| count(stone, blinks - 1)).sum()
+    }
+}
+
+#[cached]
+fn next (i: u128) -> [Option<u128>; 2] {
+    match i {
+        0 => [Some(1), None],
+        i if let a = count_digits(i) && a % 2 == 0 => {
+            let div = 10u128.pow(a / 2);
+            let left = i / div;
+            let right = i % div;
+
+            [Some(left), Some(right)]
+        },
+        i => [Some(i * 2024), None]
+
+    }
+}
+
+fn _silver (data: I) -> O {
+    _solve(data, 25)
+}
+
+fn _gold (data: I) -> O {
+    _solve(data, 75)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    fn read () -> I {
+        let data = inc!(11);
+        _parse(data)
+    }
+
+    #[test]
+    fn sample () {
+        let data = "125 17";
+        let data = _parse(data);
+
+        assert_eq!(_silver(data), 55312)
+    }
+
+    #[test]
+    fn silver () {
+        let data = read();
+        let ans = _silver(data);
+
+        assert_eq!(ans, 224529)
+    }
+
+    #[test]
+    fn gold () {
+        let data = read();
+        let ans = _gold(data);
+
+        assert_eq!(ans, 266820198587914)
+    }
+}