don't search multiple times the same value

Author: paulcacheux

src/aoc2024/day1.rs

@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+
 use crate::aoc2024::Aoc2024;
 use crate::traits::days::Day1;
 use crate::traits::ParseInput;
@@ -45,9 +47,13 @@ impl Solution<Day1> for Aoc2024 {
 
     fn part2((left, right): &(Vec<u32>, Vec<u32>)) -> u32 {
         let mut score = 0;
+        let mut counts = HashMap::new();
+
+        for &l in left {
+            let count = *counts.entry(l).or_insert_with(|| {
+                right.iter().filter(|&&r| r == l).count() as u32
+            });
 
-        for l in left {
-            let count = right.iter().filter(|&r| r == l).count() as u32;
             score += l * count;
         }