day6

src/day6.rs

@@ -0,0 +1,72 @@
+use std::collections::HashSet;
+
+use aoc_runner_derive::{aoc, aoc_generator};
+use itertools::Itertools;
+
+#[aoc_generator(day6, part1)]
+fn parse(input: &str) -> Vec<usize> {
+    input.split("\n\n")
+    .map(|group| {
+        group.chars()
+            .filter(|char| !char.is_ascii_whitespace())
+            .collect::<HashSet<_>>().len()
+        }).collect_vec()
+}
+
+#[aoc(day6, part1)]
+fn part1(input: &Vec<usize>) -> usize {
+    input.iter().sum()
+}
+
+#[aoc_generator(day6, part2)]
+fn parse2(input: &str) -> Vec<usize> {
+    input.split("\n\n")
+    .map(|group| {
+        let people = group.lines().collect_vec();
+        let mut first = people[0].chars().collect_vec();
+        for person in &people[1..] {
+            first = first.iter()
+                .cloned()
+                .filter(|question| person.contains(*question))
+                .collect_vec()
+        }
+        first.len()
+    }).collect_vec()
+}
+
+#[aoc(day6, part2)]
+fn part2(input: &Vec<usize>) -> usize {
+    input.iter().sum()
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+const EX: &str = r"abc
+
+a
+b
+c
+
+ab
+ac
+
+a
+a
+a
+a
+
+b";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 11);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse2(EX)), 6);
+    }
+}

src/lib.rs

@@ -1,3 +1,4 @@
+mod day6;
 mod day5;
 mod day1;
 mod day4;