day13

src/day13.rs

@@ -0,0 +1,113 @@
+use std::collections::HashSet;
+use aoc_runner_derive::{aoc, aoc_generator};
+
+type Coordinates = (i32, i32);
+
+#[aoc_generator(day13)]
+fn parse(input: &str) -> Vec<HashSet<Coordinates>> {
+    input.split("\n\n")
+        .map(|pattern| {
+            let mut map: HashSet<Coordinates> = HashSet::new();
+            for (y, line) in pattern.lines().into_iter().enumerate() {
+                for (x, char) in line.chars().enumerate() {
+                    if char == '#' {
+                        map.insert((x as i32 + 1, y as i32 + 1));
+                    }
+                }
+            }
+            map
+        }).collect::<Vec<_>>()
+}
+
+fn reflection((x, y): &Coordinates, pattern: &HashSet<Coordinates>, max_x: i32, max_y: i32, axis: &i32, is_column: bool) -> bool {
+    if is_column {
+        x <= axis && (2 * axis - x + 1 > max_x || pattern.contains(&(2 * axis - x + 1, *y)))
+            || x > axis && (2 * axis - x + 1 < 1 || pattern.contains(&(2 * axis - x + 1, *y)))
+    } else {
+        y <= axis && (2 * axis - y + 1 > max_y || pattern.contains(&(*x, 2 * axis - y + 1)))
+            || y > axis && (2 * axis - y + 1 < 1 || pattern.contains(&(*x, 2 * axis - y + 1)))
+    }
+}
+
+
+fn calc_summary(pattern: &HashSet<Coordinates>) -> usize {
+    let max_x = pattern.iter().max_by(|a, b| a.0.cmp(&b.0)).unwrap().0;
+    let max_y = pattern.iter().max_by(|a, b| a.1.cmp(&b.1)).unwrap().1;
+
+    ((1..max_x)
+        .find(|column| {
+            pattern.iter()
+                .all(|coords| {
+                    reflection(coords, pattern, max_x, max_y, column, true)
+                })
+        }).unwrap_or(0) 
+        + 100 * (1..max_y)
+        .find(|row| {
+            pattern.iter().all(|coordinates| {
+                reflection(coordinates, pattern, max_x, max_y, row, false)
+            })
+        })
+        .unwrap_or(0)) as usize
+}
+
+
+#[aoc(day13, part1)]
+fn part1(input: &Vec<HashSet<Coordinates>>) -> usize {
+    input.iter().map(calc_summary).sum()
+}
+
+fn calc_summary_part2(pattern: &HashSet<Coordinates>) -> usize {
+    let max_x = pattern.iter().max_by(|a, b| a.0.cmp(&b.0)).unwrap().0;
+    let max_y = pattern.iter().max_by(|a, b| a.1.cmp(&b.1)).unwrap().1;
+
+    ((1..max_x)
+        .find(|column| {
+            pattern.iter().filter(|coords| {
+                reflection(coords, pattern, max_x, max_y, column, true)
+            }).count() == pattern.len() - 1
+        }).unwrap_or(0) 
+        + 100 * (1..max_y)
+        .find(|row| {
+            pattern.iter().filter(|coordinates| {
+                reflection(coordinates, pattern, max_x, max_y, row, false)
+            }).count() == pattern.len() - 1
+        })
+        .unwrap_or(0)) as usize
+}
+
+#[aoc(day13, part2)]
+fn part2(input: &Vec<HashSet<Coordinates>>) -> usize {
+    input.iter().map(calc_summary_part2).sum()
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const EX: &str = r"#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+
+#...##..#
+#....#..#
+..##..###
+#####.##.
+#####.##.
+..##..###
+#....#..#";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 405);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX)), 400);
+    }
+}

src/lib.rs

@@ -1,3 +1,4 @@
+mod day13;
 mod day12;
 mod day4;
 mod day2;