part 2 done

2022-aoc/src/d3.rs

@@ -1,11 +1,11 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::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) {
+    if item.is_ascii_lowercase() {
         *item as u32 - 96
     } else {
         *item as u32 - 38
@@ -25,14 +25,34 @@ fn parse_input(input: &str) -> Vec<Contents> {
     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);
+#[aoc_generator(day3, part2)]
+fn parse_input2(input: &str) -> Vec<u32> {
+    let mut out = Vec::with_capacity(input.len() / 3);
+    let lines: Vec<&str> = input.lines().collect();
+    for group in lines.chunks_exact(3) {
+        let [x, y, z] = group else {panic!()};
+        let x: HashSet<char> = HashSet::from_iter(x.chars());
+        let y = HashSet::from_iter(y.chars());
+        let z = HashSet::from_iter(z.chars());
+        let xy: HashSet<char> = x.intersection(&y).copied().collect();
+        let common = xy.intersection(&z).next().unwrap();
+        out.push(get_priority(common));
     }
 
     out
 }
+
+#[aoc_run(day3, part1)]
+fn part1(sacks: &[Contents]) -> u32 {
+    let mut out = 0;
+    for (lo, hi) in sacks {
+        let common = lo.intersection(hi).next().unwrap();
+        out += get_priority(common);
+    }
+    out
+}
+
+#[aoc_run(day3, part2)]
+fn p2(items: &[u32]) -> u32 {
+    items.iter().sum()
+}