solution: day6

src/bin/06.rs

@@ -0,0 +1,49 @@
+use hashbrown::HashMap;
+use itertools::Itertools;
+
+fn solve(input: &str, min: bool) -> String {
+    let mut data: HashMap<_, HashMap<_, _>> = HashMap::new();
+    for line in input.lines() {
+        for (idx, x) in line.chars().enumerate() {
+            *data.entry(idx).or_default().entry(x).or_insert(0) += 1;
+        }
+    }
+
+    if min {
+        data.iter()
+            .sorted_by_key(|(k, _)| *k)
+            .map(|(_, v)| *v.iter().min_by_key(|(_, v)| *v).unwrap().0)
+            .collect::<String>()
+    } else {
+        data.iter()
+            .sorted_by_key(|(k, _)| *k)
+            .map(|(_, v)| *v.iter().max_by_key(|(_, v)| *v).unwrap().0)
+            .collect::<String>()
+    }
+}
+
+pub fn part_one(input: &str) -> Option<String> {
+    Some(solve(input, false))
+}
+pub fn part_two(input: &str) -> Option<String> {
+    Some(solve(input, true))
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 6);
+    aoc::solve!(1, part_one, input);
+    aoc::solve!(2, part_two, input);
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        let input = aoc::read_file("examples", 6);
+        assert_eq!(part_one(&input), Some("easter".to_string()));
+    }
+    #[test]
+    fn test_part_two() {
+        let input = aoc::read_file("examples", 6);
+        assert_eq!(part_two(&input), Some("advent".to_string()));
+    }
+}

src/examples/06.txt

@@ -0,0 +1,16 @@
+eedadn
+drvtee
+eandsr
+raavrd
+atevrs
+tsrnev
+sdttsa
+rasrtv
+nssdts
+ntnada
+svetve
+tesnvt
+vntsnd
+vrdear
+dvrsen
+enarar