day1

.gitignore

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+**/Cargo.lock
+**/target

day1/Cargo.toml

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+[package]
+name = "day1"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

day1/src/main.rs

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+use std::collections::{BTreeMap, BinaryHeap};
+
+fn main() {
+    let input = std::fs::read_to_string("input.txt").unwrap();
+    let lines = input.lines();
+    let mut left_vecs = BinaryHeap::new();
+    let mut right_vecs = BinaryHeap::new();
+    for line in lines {
+        let (left, right) = line.split_once("   ").unwrap();
+        left_vecs.push(left.parse::<i32>().unwrap());
+        right_vecs.push(right.parse::<i32>().unwrap());
+    }
+    let left_sorted = left_vecs.into_sorted_vec();
+    let right_sorted = right_vecs.into_sorted_vec();
+    let mut right2count = BTreeMap::new();
+    for right in right_sorted.iter() {
+        *right2count.entry(right).or_insert(0) += 1;
+    }
+
+    let mut sum = 0;
+    let mut score = 0;
+    for (left, right) in left_sorted.iter().zip(right_sorted.iter()) {
+        sum += left.abs_diff(*right);
+        let s = right2count.get(left).unwrap_or(&0);
+        score += left * s;
+    }
+    println!("{}, {}", sum, score);
+}