25th day

Author: majcn

data/examples/25.txt

@@ -0,0 +1,39 @@
+#####
+.####
+.####
+.####
+.#.#.
+.#...
+.....
+
+#####
+##.##
+.#.##
+...##
+...#.
+...#.
+.....
+
+.....
+#....
+#....
+#...#
+#.#.#
+#.###
+#####
+
+.....
+.....
+#.#..
+###..
+###.#
+###.#
+#####
+
+.....
+.....
+.....
+#....
+#.#..
+#.#.#
+#####

src/bin/25.rs

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+advent_of_code::solution!(25);
+
+fn parse_data(input: &str) -> Vec<Vec<u8>> {
+    input
+        .split("\n\n")
+        .map(|s| s.bytes().filter(|c| !c.is_ascii_whitespace()).collect())
+        .collect()
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let schematics = parse_data(input);
+
+    let mut locks_and_keys = [
+        Vec::with_capacity(schematics.len()),
+        Vec::with_capacity(schematics.len()),
+    ];
+
+    for schematic in schematics {
+        let locks_and_keys_index = if schematic[0] == b'#' { 0 } else { 1 };
+
+        let mut pins = [0; 5];
+        schematic
+            .into_iter()
+            .enumerate()
+            .for_each(|(i, c)| pins[i % 5] += if c == b'#' { 1 } else { 0 });
+
+        locks_and_keys[locks_and_keys_index].push(pins);
+    }
+
+    let [locks, keys] = locks_and_keys;
+
+    let result = locks
+        .into_iter()
+        .flat_map(|lock| std::iter::repeat(lock).zip(keys.iter()))
+        .filter(|(lock, key)| lock.iter().zip(key.iter()).all(|(l, k)| l + k <= 7))
+        .count() as u32;
+
+    Some(result)
+}
+
+pub fn part_two(_input: &str) -> Option<String> {
+    // "Thank you Eric for another wonderful year of AoC!"
+    Some(String::from("⭐️⭐️"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let input = advent_of_code::template::read_file("examples", DAY);
+        let result = part_one(&input);
+        assert_eq!(result, Some(3));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let input = advent_of_code::template::read_file("examples", DAY);
+        let result = part_two(&input);
+        assert_eq!(result, Some(String::from("⭐️⭐️")));
+    }
+}