Solve 01

src/bin/01.rs

@@ -0,0 +1,38 @@
+use aoc::*;
+use itertools::Itertools;
+
+const INPUT: &str = include_str!("../../input/01");
+
+fn main() {
+    assert_example!(part1, "01-test", 11);
+    println!("Part 1: {}", part1(INPUT));
+    assert_example!(part2, "01-test", 31);
+    println!("Part 2: {}", part2(INPUT));
+}
+
+fn part1(input: &str) -> usize {
+    let (left, right) = parse(input);
+    let pairs = left.into_iter().sorted().zip(right.into_iter().sorted());
+    pairs.map(|(left, right)| left.abs_diff(right)).sum()
+}
+
+fn part2(input: &str) -> usize {
+    let (left, right) = parse(input);
+    left.into_iter().map(|l| similarity(l, &right)).sum()
+}
+
+fn similarity(left: usize, right: &[usize]) -> usize {
+    let count = right.iter().filter(|&&r| r == left).count();
+    count * left
+}
+
+fn parse(input: &str) -> (Vec<usize>, Vec<usize>) {
+    input.lines().map(parse_line).unzip()
+}
+
+fn parse_line(line: &str) -> (usize, usize) {
+    let mut numbers = line.split_whitespace();
+    let left = numbers.next().unwrap().parse().unwrap();
+    let right = numbers.next().unwrap().parse().unwrap();
+    (left, right)
+}