y2024d6

y2024/resources/6_input.txt

@@ -0,0 +1,130 @@
+.........................#...........#.#...#...............#..............##.....................#...........#..#.........#.......
+.....................#.................#.......#.........................#...........#.#.......#..................................
+.........#...........#........#.........#.........#...........#........................................#.........................#
+.......#.........................#...........................#.............#......................................................
+..................#................##...............#.#.....................##............#.......................................
+......#...#................#..................................................................#....#.#............................
+.......##................#........#..#.......#......................................#........#............#......###..........#...
+.....................#....................................................#...........#..#...#..........................#.........
+...........#....#...........................#.#...............#..#....................................#..............#......#.....
+.....#........##...............#.......#..#..............................................#..........................#.............
+.#.........#.#...........................#..........................#......................#...........#........#.................
+.................................................................#..#.#.......#..#................................................
+...............................................#.......#...................#....................#.................................
+.......#......#......#......................#...............................#.....##........#...........#......#..................
+........................................................................................................#.....#.#.................
+..#...............................#.#..................................#.............#............................................
+..............#..........................................#.....#.....#..........................#....#.........#..................
+...................................#........................................#................#...........##.....#....#............
+.#.....................................#.......#........................#...................##............#.......................
+.#..................#...........#...........................................................................................#.....
+........................#...................................................##.................................#..#..........##...
+........#............................#.......#...........................#.#...#...................................#.....#........
+...............................#............#.....#......................#.......#...#........................#...................
+.........#.............#.................................................#.......................................#....#...........
+...................................................................#...#.................................#...................#....
+...#.....................#...#...............#..................................................#...#...#.........................
+...................#........#....#....#..#..#...................#.........#..................#..#....#.......#.#.................#
+..............................#........................................#......#.....#..............##................#............
+............#..#.............#.......#........................................................##........#.....#...................
+.....#.............................................................#...#.#.#.............................#..#.#...........#.......
+.......#....#............................................#.................................#...................................#..
+..#.................#.......#..........................#........................................#...............#..............#..
+....#.#...................#............................#..#.......................................................................
+.......................#...............#..............#......#......................#.....................#..............#........
+.#..........#.......................................................................#....................................#........
+.#.......#..................................................................#.....................................................
+..................................................#.............#.............................................#................#.#
+.......................#......#....#................#......................................................#.......#.........#....
+..........................#.#........................................................#......#................................#....
+....................................................................#...............................#.............................
+..#...........#..............................#..#....#............................#...............##..............#...#...#...#..#
+...................................#................................................................#....#...................#....
+..#....#........#..##....#........................#...#...................................#.......................................
+...................#................................................................................................#.............
+.......#........#................#...#.......................................................................#....................
+..............#....................#..........................##.........#.....................................#..................
+.........................................................................#.................#........................#.............
+.............................#..........#.......................................................#......................#..........
+............###....................................................................#.......................#......................
+........#........#...........#.............................#....................#..........#.........................#.#.....#....
+.........................................................................................................#..#.....................
+#.#.....#..........................................................#.....................#........................................
+........##..........#....................................................#..#........#.......#........#................#..........
+.............................................#..........................#.........#........................#......................
+...........................##.............#........................#.#........................#..#................#.....#........#
+#...#..............................................#........#...................................................#.................
+.............#................#............................#............#.........................................................
+#..........................#............#.....................#.....#.................#......#...##...#.............#.#...........
+.....................#...#..#....#...................................#....................#..............#........#...............
+.......................#.................#...........#....#.......#...........................................#..#................
+.........#...........#.#.........#.........................#.....#................................................................
+....................#........#...................................................................#............#..#.#.#............
+..........#.......................#.......................#.......................................................................
+......................................#......#............................#..............................................#........
+.....................#...#.................#.............................#....#...................................................
+..............##...................................................................#......................................##......
+.....#....#...............................................#.......#.##........#.#.............#...............#...................
+....................................#......................#........#.......................................................#.....
+.....#.........................................#.....................#.............#.................#..................#.........
+................................#.........#..#............................................#.........................#.............
+....#.#.....................#......#...................................#..........................................#..#.....#...#..
+.........##.......................#..........................................#.........................#...##.....................
+...............................................................#................................................................#.
+............#.........................................##.......................................#..................................
+.............................#..............................#..................#.........#.....#..................................
+..........................................................#...#.....#..................#................................#.........
+......#...................#.........................................................................................#.............
+#...............................#...........................#.....................................................................
+.......#........#.................................................#.......................................................#.......
+.#......................................................#..............#..................................#...........#...........
+.............#..#.#.......................#..........#......#.##.........................................................#..#.....
+.......#...............#........#......................................................................#..#...........#...........
+............#.........................................#................................................#...................#......
+............#...........................................#.#.......#....................................#..........................
+...........................................#.........................................................#..............#.............
+..................#..#....................................................#..................#....................................
+..#........................#........#.............................................................................................
+.............#........#......................#.......................................#...#....#............................#......
+............#.......#.............#...#...........#.#.................................#.................##........................
+.....................................................................................#.........#.......................#.....#....
+.................#................................#..#....#......#..........................................#.....#...............
+..#...............................#........................................................#.......#...#............#.............
+#.........#..#..#.....................................#....................................#................#.................#...
+.......................#..#...#............................................................................#..#.....#.......##....
+..........#............#.......................#.........................^......#.#...................................#...........
+...##........................##..........#..........#.................#...............#...........#.....##........................
+..............#............#..........................#....#...........#......#......#......................#.....................
+......#.....#....................................................#............#.#......................................#..........
+......#.............................#......................#...............................#........#.............................
+.#..........#.............................................#.............................................#.........................
+...............................##.................................................................................................
+.....................#................................................#...............#............#...............#.....#.....#..
+..................#...........................................................................#...........#...................#...
+##..............................#.#...#.#...............................#...........#.#...................#.......................
+......................#.........#...................................#.................#...........................................
+.......................#............................................................................#.........##...........#......
+.....................................................................#.......#.....#.......................................#......
+#....................................#........#.#.................................................................##.....#........
+..............#..............................#......#..........###.........#................#..............#..................#...
+..................................#..............................#.................##.............................#...#...........
+...............#......#........................#....#........#............#.........#..........#..............#......#............
+...#...........#........#...#...........................#.............#.....................................#.....................
+..............###............#...........................................................#.............#.........##..#............
+............#................................................#.......#..................#....#....................................
+.........#.#...#.....#...........................#.....##......#.....................#..#........#......#.........................
+.#....#.......#.......................#.................................................................#.......#..............#..
+...................#................................................................#.............#...#...........#.........#.....
+.......#.#.......#.......................#....#.....#...............#...#.....#...........................................#.......
+.......#........#...........................................#...........#.........................#....#.......#..................
+..................................#.#.................#.#............................................#...........#....#...........
+....##......#.............#...................................#...#.........#...........................#......#..................
+.........................#......#....#...#........................................................................................
+...#...............#............................................................................#...........................#.....
+....##.#..............................................#............#................#................................#......#.....
+.........#...........................................#...#.......##..............................#................................
+..................#..........#......#.......#......................................#........#...............#......#...........##.
+........................................#......#..........#......................................................................#
+..............#...#...................#.....#..........................................................#..............#......#....
+...#........#........................#...#................#........#.............................##..........................#....
+............#............................#.#........................#.................................#..........................#

y2024/src/bin/d6.rs

@@ -0,0 +1,20 @@
+use std::fs;
+
+use y2024::days::d6;
+
+fn main() {
+    part1();
+    part2();
+}
+
+fn part1() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/6_input.txt")).unwrap();
+    println!("{}", d6::process_part1(&content));
+}
+
+fn part2() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/6_input.txt")).unwrap();
+    println!("{}", d6::process_part2(&content));
+}

y2024/src/days/d6.rs

@@ -0,0 +1,331 @@
+use std::{collections::HashSet, error::Error, fmt::Display};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+enum GuardDirection {
+    Up,
+    Down,
+    Left,
+    Right,
+}
+
+impl GuardDirection {
+    fn turn_right(&mut self) {
+        *self = match self {
+            GuardDirection::Up => GuardDirection::Right,
+            GuardDirection::Down => GuardDirection::Left,
+            GuardDirection::Left => GuardDirection::Up,
+            GuardDirection::Right => GuardDirection::Down,
+        };
+    }
+}
+
+impl From<GuardDirection> for char {
+    fn from(value: GuardDirection) -> Self {
+        match value {
+            GuardDirection::Up => '^',
+            GuardDirection::Down => 'v',
+            GuardDirection::Left => '<',
+            GuardDirection::Right => '>',
+        }
+    }
+}
+
+impl TryFrom<char> for GuardDirection {
+    type Error = Box<dyn Error>;
+
+    fn try_from(value: char) -> std::result::Result<GuardDirection, Box<dyn Error>> {
+        match value {
+            '^' => Ok(Self::Up),
+            'v' => Ok(Self::Down),
+            '<' => Ok(Self::Left),
+            '>' => Ok(Self::Right),
+            _ => Err(Box::from(format!("{value} is not a valid direction"))),
+        }
+    }
+}
+
+impl Display for GuardDirection {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            GuardDirection::Up => write!(f, "^"),
+            GuardDirection::Down => write!(f, "v"),
+            GuardDirection::Left => write!(f, "<"),
+            GuardDirection::Right => write!(f, ">"),
+        }
+    }
+}
+
+pub fn process_part1(input: &str) -> i32 {
+    let grid = input
+        .lines()
+        .map(|line| line.chars().collect::<Vec<char>>())
+        .collect::<Vec<Vec<char>>>();
+    get_visited_positions(grid, true).len() as i32
+}
+
+fn get_visited_positions(grid: Vec<Vec<char>>, initial: bool) -> HashSet<(i32, i32)> {
+    let width = grid[1].len() as i32;
+    let height = grid.len() as i32;
+    let mut crates: Vec<(i32, i32)> = Vec::new();
+    let mut guard_position = (0, 0);
+    let mut guard_direction = GuardDirection::Up;
+    for (row, line) in grid.into_iter().enumerate() {
+        for (col, chara) in line.into_iter().enumerate() {
+            if chara == '#' {
+                crates.push((col as i32, row as i32));
+            }
+            if chara == '.' {
+                continue;
+            }
+            if GuardDirection::try_from(chara).is_ok() {
+                guard_position = (col as i32, row as i32);
+                guard_direction = GuardDirection::try_from(chara).unwrap();
+            }
+        }
+    }
+    let mut visited_positions = HashSet::new();
+    if initial {
+        visited_positions.insert(guard_position);
+    }
+    loop {
+        match guard_direction {
+            GuardDirection::Up => {
+                let mut closest = (guard_position.0, -1);
+                crates.iter().for_each(|&crate_pos| {
+                    if guard_position.0 == crate_pos.0
+                        && guard_position.1 > crate_pos.1
+                        && guard_position.1 - crate_pos.1 < guard_position.1 - closest.1
+                    {
+                        closest = crate_pos;
+                    }
+                });
+                for idx in ((closest.1 + 1)..guard_position.1).rev() {
+                    visited_positions.insert((guard_position.0, idx));
+                    if idx == 0 {
+                        return visited_positions;
+                    }
+                }
+                guard_position.1 = closest.1 + 1;
+                guard_direction.turn_right();
+            }
+            GuardDirection::Down => {
+                let mut closest = (guard_position.0, height);
+                crates.iter().for_each(|&crate_pos| {
+                    if guard_position.0 == crate_pos.0
+                        && guard_position.1 < crate_pos.1
+                        && crate_pos.1 - guard_position.1 < closest.1 - guard_position.1
+                    {
+                        closest = crate_pos;
+                    }
+                });
+                for idx in (guard_position.1 + 1)..closest.1 {
+                    visited_positions.insert((guard_position.0, idx));
+                    if idx == height - 1 {
+                        return visited_positions;
+                    }
+                }
+                guard_position.1 = closest.1 - 1;
+                guard_direction.turn_right();
+            }
+            GuardDirection::Left => {
+                let mut closest = (-1, guard_position.1);
+                crates.iter().for_each(|&crate_pos| {
+                    if guard_position.1 == crate_pos.1
+                        && guard_position.0 > crate_pos.0
+                        && guard_position.0 - crate_pos.0 < guard_position.0 - closest.0
+                    {
+                        closest = crate_pos;
+                    }
+                });
+                for idx in ((closest.0 + 1)..guard_position.0).rev() {
+                    visited_positions.insert((idx, guard_position.1));
+                    if idx == 0 {
+                        return visited_positions;
+                    }
+                }
+                guard_position.0 = closest.0 + 1;
+                guard_direction.turn_right();
+            }
+            GuardDirection::Right => {
+                let mut closest = (width, guard_position.1);
+                crates.iter().for_each(|&crate_pos| {
+                    if guard_position.1 == crate_pos.1
+                        && guard_position.0 < crate_pos.0
+                        && crate_pos.0 - guard_position.0 < closest.0 - guard_position.0
+                    {
+                        closest = crate_pos;
+                    }
+                });
+                for idx in (guard_position.0 + 1)..closest.0 {
+                    visited_positions.insert((idx, guard_position.1));
+                    if idx == width - 1 {
+                        return visited_positions;
+                    }
+                }
+                guard_position.0 = closest.0 - 1;
+                guard_direction.turn_right();
+            }
+        };
+    }
+}
+
+// 1424
+pub fn process_part2(input: &str) -> i32 {
+    let grid = input
+        .lines()
+        .map(|line| line.chars().collect::<Vec<char>>())
+        .collect::<Vec<Vec<char>>>();
+    let width = grid[1].len() as i32;
+    let height = grid.len() as i32;
+    let mut crates: Vec<(i32, i32)> = Vec::new();
+    let possible_obstacles: Vec<(i32, i32)> = Vec::from_iter(get_visited_positions(grid, false));
+    let mut initial_guard_position = (0, 0);
+    let mut initial_guard_direction = GuardDirection::Up;
+    for (row, line) in input.lines().enumerate() {
+        for (col, chara) in line.chars().enumerate() {
+            if chara == '#' {
+                crates.push((col as i32, row as i32));
+            }
+            if chara == '.' {
+                continue;
+            }
+            if GuardDirection::try_from(chara).is_ok() {
+                initial_guard_position = (col as i32, row as i32);
+                initial_guard_direction = GuardDirection::try_from(chara).unwrap();
+            }
+        }
+    }
+    let mut loops = 0;
+    for possible_obstacle in possible_obstacles {
+        let mut visited_obstacles = HashSet::new();
+        crates.push(possible_obstacle);
+        let mut guard_position = initial_guard_position;
+        let mut guard_direction = initial_guard_direction;
+        'loop_finder: loop {
+            match guard_direction {
+                GuardDirection::Up => {
+                    let mut closest = (guard_position.0, -1);
+                    crates.iter().for_each(|&crate_pos| {
+                        if guard_position.0 == crate_pos.0
+                            && guard_position.1 > crate_pos.1
+                            && guard_position.1 - crate_pos.1 < guard_position.1 - closest.1
+                        {
+                            closest = crate_pos;
+                        }
+                    });
+                    guard_position.1 = closest.1 + 1;
+                    if closest.1 == -1 {
+                        break 'loop_finder;
+                    }
+                    if visited_obstacles
+                        .contains(&((guard_position.0, closest.1 + 1), guard_direction))
+                    {
+                        loops += 1;
+                        break 'loop_finder;
+                    }
+                    visited_obstacles.insert(((guard_position.0, closest.1 + 1), guard_direction));
+                    guard_direction.turn_right();
+                }
+                GuardDirection::Down => {
+                    let mut closest = (guard_position.0, height);
+                    crates.iter().for_each(|&crate_pos| {
+                        if guard_position.0 == crate_pos.0
+                            && guard_position.1 < crate_pos.1
+                            && crate_pos.1 - guard_position.1 < closest.1 - guard_position.1
+                        {
+                            closest = crate_pos;
+                        }
+                    });
+                    guard_position.1 = closest.1 - 1;
+                    if closest.1 == height {
+                        break 'loop_finder;
+                    }
+                    if visited_obstacles
+                        .contains(&((guard_position.0, closest.1 - 1), guard_direction))
+                    {
+                        loops += 1;
+                        break 'loop_finder;
+                    }
+                    visited_obstacles.insert(((guard_position.0, closest.1 - 1), guard_direction));
+                    guard_direction.turn_right();
+                }
+                GuardDirection::Left => {
+                    let mut closest = (-1, guard_position.1);
+                    crates.iter().for_each(|&crate_pos| {
+                        if guard_position.1 == crate_pos.1
+                            && guard_position.0 > crate_pos.0
+                            && guard_position.0 - crate_pos.0 < guard_position.0 - closest.0
+                        {
+                            closest = crate_pos;
+                        }
+                    });
+                    guard_position.0 = closest.0 + 1;
+                    if closest.0 == -1 {
+                        break 'loop_finder;
+                    }
+                    if visited_obstacles
+                        .contains(&((closest.0 + 1, guard_position.1), guard_direction))
+                    {
+                        loops += 1;
+                        break 'loop_finder;
+                    }
+                    visited_obstacles.insert(((closest.0 + 1, guard_position.1), guard_direction));
+                    guard_direction.turn_right();
+                }
+                GuardDirection::Right => {
+                    let mut closest = (width, guard_position.1);
+                    crates.iter().for_each(|&crate_pos| {
+                        if guard_position.1 == crate_pos.1
+                            && guard_position.0 < crate_pos.0
+                            && crate_pos.0 - guard_position.0 < closest.0 - guard_position.0
+                        {
+                            closest = crate_pos;
+                        }
+                    });
+                    guard_position.0 = closest.0 - 1;
+                    if closest.0 == width {
+                        break 'loop_finder;
+                    }
+                    if visited_obstacles
+                        .contains(&((closest.0 - 1, guard_position.1), guard_direction))
+                    {
+                        loops += 1;
+                        break 'loop_finder;
+                    }
+                    visited_obstacles.insert(((closest.0 - 1, guard_position.1), guard_direction));
+                    guard_direction.turn_right();
+                }
+            };
+        }
+        crates.pop();
+    }
+    loops
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT: &str = "....#.....
+.........#
+..........
+..#.......
+.......#..
+..........
+.#..^.....
+........#.
+#.........
+......#...";
+
+    #[test]
+    fn part1() {
+        let result = process_part1(INPUT);
+        assert_eq!(result, 41);
+    }
+
+    #[test]
+    fn part2() {
+        let result = process_part2(INPUT);
+        assert_eq!(result, 6);
+    }
+}

y2024/src/days/mod.rs

@@ -7,3 +7,5 @@ pub mod d3;
 pub mod d4;
 
 pub mod d5;
+
+pub mod d6;