y2024d1

y2024/src/days/d1.rs

@@ -0,0 +1,62 @@
+use std::{collections::HashMap, iter::zip};
+
+pub fn process_part1(input: &str) -> i32 {
+    let mut left = Vec::new();
+    let mut right = Vec::new();
+    input.lines().for_each(|line| {
+        let (left_val, right_val) = line.split_once("   ").unwrap();
+        left.push(left_val.parse::<i32>().unwrap());
+        right.push(right_val.parse::<i32>().unwrap());
+    });
+    left.sort();
+    right.sort();
+    let mut res = 0;
+    for (left_val, right_val) in zip(left, right) {
+        res += (left_val - right_val).abs();
+    }
+    res
+}
+
+pub fn process_part2(input: &str) -> i32 {
+    let mut left = Vec::new();
+    let mut right = HashMap::new();
+    input.lines().for_each(|line| {
+        let (left_val, right_val) = line.split_once("   ").unwrap();
+        left.push(left_val.parse::<i32>().unwrap());
+        right
+            .entry(right_val.parse::<i32>().unwrap())
+            .and_modify(|value| *value += 1)
+            .or_insert(1);
+    });
+    left.sort();
+    let mut res = 0;
+    for left_val in left {
+        let right_val_count = right.get(&left_val).unwrap_or(&0);
+        res += left_val * right_val_count;
+    }
+    res
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT: &str = "3   4
+4   3
+2   5
+1   3
+3   9
+3   3";
+
+    #[test]
+    fn part1() {
+        let result = process_part1(INPUT);
+        assert_eq!(result, 11);
+    }
+
+    #[test]
+    fn part2() {
+        let result = process_part2(INPUT);
+        assert_eq!(result, 31);
+    }
+}

y2024/src/days/mod.rs

@@ -0,0 +1,2 @@
+pub mod d1;
+