solve year 2022 day 03 part 1

src/year2022/day03.rs

@@ -0,0 +1,39 @@
+use std::collections::BTreeSet;
+
+fn char_to_score(c: char) -> u32 {
+    match c {
+        'a'..='z' => c as u32 - 96,
+        'A'..='Z' => c as u32 - 38,
+        _ => unreachable!(),
+    }
+}
+
+pub fn part1(input: &str) -> impl std::fmt::Display {
+    input
+        .lines()
+        .map(|l| l.split_at(l.len() / 2))
+        .map(|(l, r)| {
+            let a: BTreeSet<char> = l.chars().collect();
+            let b: BTreeSet<char> = r.chars().collect();
+            a.intersection(&b)
+                .next()
+                .expect("We know there is at least one")
+                .clone()
+        })
+        .map(char_to_score)
+        .sum::<u32>()
+}
+
+pub fn part2(input: &str) -> impl std::fmt::Display {
+    ""
+}
+
+#[test]
+fn test_part1() {
+    assert_eq!("15", part1("A Y\nB X\nC Z").to_string())
+}
+
+#[test]
+fn test_part2() {
+    assert_eq!("12", part2("A Y\nB X\nC Z").to_string())
+}