From c7785785a26b7847dd303742545fc8bb35773a4c Mon Sep 17 00:00:00 2001
From: nekineki <nekineki@nekineki.net>
Date: Wed, 11 Dec 2024 07:31:43 +0100
Subject: simplify day11

---
 2024/day11.rs | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/2024/day11.rs b/2024/day11.rs
index 0730c5f..93ea695 100644
--- a/2024/day11.rs
+++ b/2024/day11.rs
@@ -23,8 +23,8 @@ fn evolve(s: &Vec<u64>) -> Vec<u64> {
     return sn;
 }
 
-fn evolve_fast(n: u64, depth: u64, depth_end: u64, lut: &mut HashMap<(u64, u64), u64>) -> u64 {
-    if depth == depth_end {
+fn evolve_fast(n: u64, depth: u64, lut: &mut HashMap<(u64, u64), u64>) -> u64 {
+    if depth == 0 {
         return 1;
     }
 
@@ -32,20 +32,20 @@ fn evolve_fast(n: u64, depth: u64, depth_end: u64, lut: &mut HashMap<(u64, u64),
         return *val;
     }
 
-    let sum = if n == 0 {
-        evolve_fast(1, depth + 1, depth_end, lut)
+    let val = if n == 0 {
+        evolve_fast(1, depth - 1, lut)
     } else if n.checked_ilog(10).unwrap() % 2 == 1 {
         let pow = 10_u64.pow(n.checked_ilog(10).unwrap() / 2 + 1);
-        let a = evolve_fast(n / pow, depth + 1, depth_end, lut);
-        let b = evolve_fast(n % pow, depth + 1, depth_end, lut);
+        let a = evolve_fast(n / pow, depth - 1, lut);
+        let b = evolve_fast(n % pow, depth - 1, lut);
         a + b
     } else {
-        evolve_fast(n * 2024, depth + 1, depth_end, lut)
+        evolve_fast(n * 2024, depth - 1, lut)
     };
 
-    lut.insert((n, depth), sum);
+    lut.insert((n, depth), val);
 
-    return sum;
+    return val;
 }
 
 fn main() {
@@ -70,9 +70,9 @@ fn main() {
 
     let mut s2 = stones.clone();
     let mut res2 = 0;
-    let mut hm = HashMap::new();
+    let mut lut = HashMap::new();
     for n in s2 {
-        res2 += evolve_fast(n, 0, 75, &mut hm);
+        res2 += evolve_fast(n, 75, &mut lut);
     }
 
     println!("res1: {}", res1);
-- 
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