day 3, part 1 done

2022-aoc/src/d3.rs

@@ -0,0 +1,38 @@
+use std::collections::{HashMap, HashSet};
+
+use aoc_runner_derive::{aoc as aoc_run, aoc_generator};
+
+type Contents = (HashSet<char>, HashSet<char>);
+
+fn get_priority(item: &char) -> u32 {
+    if ('a'..='z').contains(item) {
+        *item as u32 - 96
+    } else {
+        *item as u32 - 38
+    }
+}
+
+#[aoc_generator(day3, part1)]
+fn parse_input(input: &str) -> Vec<Contents> {
+    let mut out = Vec::with_capacity(input.len());
+    for line in input.lines() {
+        let half_len = line.len() / 2;
+        let lo = HashSet::from_iter(line[0..half_len].chars());
+        let hi = HashSet::from_iter(line[half_len..].chars());
+        out.push((lo, hi));
+    }
+
+    out
+}
+
+#[aoc_run(day3, part1)]
+fn part1(sacks: &[Contents]) -> u32 {
+    let mut out = 0;
+    for sack in sacks {
+        let (lo, hi) = sack;
+        let common = lo.intersection(hi).into_iter().next().unwrap();
+        out += get_priority(common);
+    }
+
+    out
+}

2022-aoc/src/lib.rs

@@ -2,5 +2,6 @@ use aoc_runner_derive::aoc_lib;
 
 mod d1;
 mod d2;
+mod d3;
 
 aoc_lib! { year = 2022 }