day9 with min_idx tracking

aoc_2024/src/day9.rs

@@ -62,19 +62,30 @@ fn part2(input: &Input) -> usize {
     for i in 1..input.len() {
         input[i].0 = input[i - 1].0 + input[i - 1].1;
     }
+    let mut min_idx = [1; 10];
     // println!("{:?}", &input);
     let mut sum = 0;
     for r_idx in (0..input.len()).step_by(2).rev() {
         let val = r_idx / 2;
         let count = input[r_idx].2;
         // println!("attempt: {:?}", input[r_idx]);
-        for l_idx in (1..r_idx).step_by(2) {
+        for l_idx in (min_idx[count]..r_idx).step_by(2) {
             if input[l_idx].1 >= input[r_idx].2 {
                 // print!("{:?}", input[l_idx]);
                 input[r_idx].0 = input[l_idx].0;
                 input[l_idx].1 -= input[r_idx].2;
                 input[l_idx].0 += input[r_idx].2;
                 input[l_idx - 1].1 += input[r_idx].2;
+
+                for i in count..10 {
+                    if min_idx[i] > min_idx[count] {
+                        break;
+                    } else {
+                        while min_idx[i] <= r_idx && input[min_idx[i]].1 < i {
+                            min_idx[i] += 2;
+                        }
+                    }
+                }
                 // println!(" -> {:?}", input[l_idx]);
                 break;
             }
@@ -95,12 +106,18 @@ mod tests {
     #[test]
     fn part1_example() {
         assert_eq!(part1(&parse("2333133121414131402")), 1928);
-        // assert_eq!(part1(&parse(include_str!("../input/2024/day8.txt"))), 273);
+        assert_eq!(
+            part1(&parse(include_str!("../input/2024/day9.txt").trim_end())),
+            6337921897505
+        );
     }
 
     #[test]
     fn part2_example() {
         assert_eq!(part2(&parse("2333133121414131402")), 2858);
-        // assert_eq!(part2(&parse(include_str!("../input/2024/day8.txt"))), 1017);
+        assert_eq!(
+            part2(&parse(include_str!("../input/2024/day9.txt").trim_end())),
+            6362722604045
+        );
     }
 }