solution: day7

src/bin/07.rs

@@ -0,0 +1,83 @@
+use hashbrown::HashSet;
+use itertools::Itertools;
+
+fn is_abba(address_part: &str) -> bool {
+    for (a, b, c, d) in address_part.chars().tuple_windows() {
+        if a == d && b == c && a != b {
+            return true;
+        }
+    }
+    false
+}
+
+fn get_abas(address_part: &str) -> Vec<(char, char)> {
+    address_part
+        .chars()
+        .tuple_windows()
+        .map(|(a, b, c)| (a, b, c))
+        .filter(|(a, b, c)| a == c && a != b)
+        .map(|(a, b, _)| (a, b))
+        .collect_vec()
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let mut count = 0;
+    'lines: for line in input.lines() {
+        let mut found_abba = false;
+        for (idx, address_part) in line.split(['[', ']']).enumerate() {
+            match idx % 2 {
+                0 => found_abba |= is_abba(address_part),
+                1 => {
+                    if is_abba(address_part) {
+                        continue 'lines;
+                    }
+                }
+                _ => unreachable!(),
+            }
+        }
+        if found_abba {
+            count += 1;
+        }
+    }
+
+    Some(count)
+}
+pub fn part_two(input: &str) -> Option<u32> {
+    let mut count = 0;
+    for line in input.lines() {
+        let mut abas = HashSet::new();
+        let mut babs = HashSet::new();
+        for (idx, address_part) in line.split(['[', ']']).enumerate() {
+            match idx % 2 {
+                0 => abas.extend(get_abas(address_part)),
+                1 => babs.extend(get_abas(address_part).into_iter().map(|(a, b)| (b, a))),
+                _ => unreachable!(),
+            }
+        }
+
+        if !abas.intersection(&babs).collect_vec().is_empty() {
+            count += 1;
+        }
+    }
+
+    Some(count)
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 7);
+    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", 7);
+        assert_eq!(part_one(&input), Some(2));
+    }
+    #[test]
+    fn test_part_two() {
+        let input = aoc::read_file("examples", 7);
+        assert_eq!(part_two(&input), Some(3));
+    }
+}