Solve day 3

src/bin/03.rs

@@ -0,0 +1,50 @@
+use core::panic;
+use std::collections::HashSet;
+
+use aoc2022::*;
+use itertools::Itertools;
+
+const INPUT: &str = include_str!("../../input/03");
+
+fn main() {
+    let solution: i64 = INPUT
+        .lines()
+        .map(split_rucksack)
+        .map(find_common)
+        .map(priority)
+        .sum();
+    solved_level_1(solution);
+
+    let solution: i64 = INPUT
+        .lines()
+        .chunks(3)
+        .into_iter()
+        .map(find_common)
+        .map(priority)
+        .sum();
+    solved_level_2(solution);
+}
+
+fn find_common(parts: impl IntoIterator<Item = &'static str>) -> char {
+    parts
+        .into_iter()
+        .map(|p| p.chars().collect::<HashSet<_>>())
+        .reduce(|a, b| a.intersection(&b).copied().collect::<HashSet<_>>())
+        .unwrap()
+        .into_iter()
+        .next()
+        .unwrap()
+}
+
+fn split_rucksack(r: &str) -> [&str; 2] {
+    let (a, b) = r.split_at(r.len() / 2);
+    [a, b]
+}
+
+fn priority(item: char) -> i64 {
+    match item {
+        'a'..='z' => item as i64 - 'a' as i64 + 1,
+        'A'..='Z' => item as i64 - 'A' as i64 + 27,
+        _ => panic!("unknown item: {item}"),
+    }
+}