day14 solution

2023/src/day14.rs

@@ -0,0 +1,214 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+use std::collections::HashSet;
+
+#[aoc_generator(day14)]
+fn parse(input: &str) -> Vec<String> {
+    input
+        .lines()
+        .filter_map(|line| {
+            if !line.is_empty() {
+                Some(String::from(line))
+            } else {
+                None
+            }
+        })
+        .collect::<Vec<_>>()
+}
+
+fn map_to_string(map: &[[char; 100]; 100]) -> String {
+    let mut s = String::with_capacity(100 * 100);
+    for row in map.iter() {
+        let mut has_char = false;
+        for &c in row.iter() {
+            if c == ' ' {
+                break;
+            }
+            has_char = true;
+            s.push(c);
+        }
+        if has_char {
+            s.push('\n');
+        }
+    }
+    s
+}
+
+fn score(input: &str) -> usize {
+    let lines = input
+        .split("\n")
+        .filter_map(|t| {
+            if t.is_empty() {
+                None
+            } else {
+                Some(String::from(t))
+            }
+        })
+        .collect::<Vec<String>>();
+    let mut score = 0;
+    let total_lines = lines.len();
+    for (index, line) in lines.iter().enumerate() {
+        score += line.matches("O").collect::<Vec<_>>().len() * (total_lines - index);
+    }
+    score
+}
+
+#[aoc(day14, part1)]
+fn part1(input: &[String]) -> usize {
+    let mut map: [[char; 100]; 100] = [[' '; 100]; 100];
+    for (row, line) in input.iter().enumerate() {
+        for (col, c) in line.chars().enumerate() {
+            map[row][col] = c;
+        }
+    }
+    tilt_north(&mut map);
+    score(&map_to_string(&map))
+}
+
+fn tilt_north(map: &mut [[char; 100]; 100]) -> String {
+    for col in 0..(map[0]).len() {
+        let mut r = 0;
+        for row in (0..(map.len())).rev() {
+            if map[row][col] == ' ' {
+                continue;
+            } else if map[row][col] == '#' {
+                for rock in 1..=r {
+                    map[row + rock][col] = 'O';
+                }
+                r = 0;
+            } else if map[row][col] == 'O' {
+                r += 1;
+                map[row][col] = '.';
+            }
+        }
+        for rock in 1..=r {
+            map[rock - 1][col] = 'O';
+        }
+    }
+    map_to_string(&map)
+}
+
+fn tilt_west(map: &mut [[char; 100]; 100]) -> String {
+    for row in 0..map.len() {
+        let mut r = 0;
+        for col in (0..map[0].len()).rev() {
+            if map[row][col] == ' ' {
+                continue;
+            } else if map[row][col] == '#' {
+                for rock in 1..=r {
+                    map[row][col + rock] = 'O';
+                }
+                r = 0;
+            } else if map[row][col] == 'O' {
+                r += 1;
+                map[row][col] = '.';
+            }
+        }
+        for rock in 1..=r {
+            map[row][rock - 1] = 'O';
+        }
+    }
+    map_to_string(&map)
+}
+
+fn tilt_south(map: &mut [[char; 100]; 100]) -> String {
+    for col in 0..map[0].len() {
+        let mut r = 0;
+        let mut last_row = 100;
+        for row in 0..map.len() {
+            if map[row][col] == ' ' {
+                last_row = row;
+                break;
+            } else if map[row][col] == '#' {
+                for rock in 1..=r {
+                    map[row - rock][col] = 'O';
+                }
+                r = 0;
+            } else if map[row][col] == 'O' {
+                r += 1;
+                map[row][col] = '.';
+            }
+        }
+        for rock in 1..=r {
+            map[last_row - rock][col] = 'O';
+        }
+    }
+    map_to_string(&map)
+}
+
+fn tilt_east(map: &mut [[char; 100]; 100]) -> String {
+    for row in 0..map.len() {
+        let mut r = 0;
+        let mut last_col = 100;
+        for col in 0..map[row].len() {
+            if map[row][col] == ' ' {
+                last_col = col;
+                break;
+            } else if map[row][col] == '#' {
+                for rock in 1..=r {
+                    map[row][col - rock] = 'O';
+                }
+                r = 0;
+            } else if map[row][col] == 'O' {
+                r += 1;
+                map[row][col] = '.';
+            }
+        }
+        for rock in 1..=r {
+            map[row][last_col - rock] = 'O';
+        }
+    }
+    map_to_string(&map)
+}
+
+#[aoc(day14, part2)]
+fn part2(input: &[String]) -> usize {
+    let mut map: [[char; 100]; 100] = [[' '; 100]; 100];
+    for (row, line) in input.iter().enumerate() {
+        for (col, c) in line.chars().enumerate() {
+            map[row][col] = c;
+        }
+    }
+    let mut patterns: HashSet<String> = HashSet::new();
+    let mut seq: Vec<String> = vec![];
+    let mut iters = 0;
+    loop {
+        if iters == 1000 {
+            break;
+        }
+        tilt_north(&mut map);
+        tilt_west(&mut map);
+        tilt_south(&mut map);
+        tilt_east(&mut map);
+        let s = map_to_string(&map);
+        iters += 1;
+        seq.push(s.clone());
+        patterns.insert(s);
+    }
+
+    let score = score(&seq[999]);
+    score
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const SAMPLE_DATA: &'static str = r#"O....#....
+O.OO#....#
+.....##...
+OO.#O....O
+.O.....O#.
+O.#..O.#.#
+..O..#O..O
+.......O..
+#....###..
+#OO..#....
+"#;
+
+    #[test]
+    fn sample_data() {
+        let input = parse(&SAMPLE_DATA);
+        assert_eq!(part1(&input), 136);
+        assert_eq!(part2(&input), 64);
+    }
+}

2023/src/lib.rs

@@ -13,5 +13,6 @@ mod day10;
 mod day11;
 mod day12;
 mod day13;
+mod day14;
 
 aoc_lib! { year = 2023 }