day22 part1

2 files changed, 423 insertions, 0 deletions

diff --git a/inputs/day22 b/inputs/day22
new file mode 100644
index 0000000..14e2245
--- /dev/null
+++ b/inputs/day22
@@ -0,0 +1,202 @@
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diff --git a/src/bin/day22.rs b/src/bin/day22.rs
new file mode 100644
index 0000000..13322c6
--- /dev/null
+++ b/src/bin/day22.rs
@@ -0,0 +1,221 @@
+use std::collections::HashMap;
+
+static DAY: u8 = 22;
+
+fn main() {
+    let input = advent::read_lines(DAY);
+    println!("{DAY}a: {}", find_password(&input));
+    println!("{DAY}b: {}", 0);
+}
+
+#[derive(Clone,Copy)]
+enum Object {
+    Floor,
+    Wall,
+}
+
+enum Instruction {
+    Left,
+    Right,
+    Move { amount: isize },
+}
+
+enum Direction {
+    Left,
+    Right,
+    Up,
+    Down,
+}
+
+impl Direction {
+    fn turn_left(&self) -> Direction {
+        match self {
+            Direction::Left => Direction::Down,
+            Direction::Right => Direction::Up,
+            Direction::Up => Direction::Left,
+            Direction::Down => Direction::Right,
+        }
+    }
+
+    fn turn_right(&self) -> Direction {
+        match self {
+            Direction::Left => Direction::Up,
+            Direction::Right => Direction::Down,
+            Direction::Up => Direction::Right,
+            Direction::Down => Direction::Left,
+        }
+    }
+}
+
+struct Map {
+    map: HashMap<(isize,isize),Object>,
+    instructions: Vec<Instruction>,
+    pos: (isize,isize),
+    direction: Direction,
+}
+
+impl Map {
+    fn new(input: &[String]) -> Map {
+        let mut map = HashMap::new();
+        let mut pos = None;
+        for (y, line) in input.iter().enumerate() {
+            if line.is_empty() {
+                break;
+            }
+            for (x, c) in line.chars().enumerate() {
+                let (x, y) = (x as isize, y as isize);
+                match c {
+                    '.' => {
+                        if pos.is_none() {
+                            pos = Some((x, y));
+                        }
+                        map.insert((x,y), Object::Floor);
+                    }
+                    '#' => { map.insert((x,y), Object::Wall); }
+                    _ => continue,
+                }
+            }
+        }
+
+        let mut instructions = Vec::new();
+        let mut number = 0;
+        for c in input.last().unwrap().chars() {
+            if c.is_ascii_digit() {
+                number *= 10;
+                number += c.to_digit(10).unwrap() as isize;
+            } else {
+                if number > 0 {
+                    instructions.push(Instruction::Move { amount: number });
+                    number = 0;
+                }
+                match c {
+                    'R' => instructions.push(Instruction::Right),
+                    'L' => instructions.push(Instruction::Left),
+                    _ => unimplemented!(),
+                }
+            }
+        }
+        if number > 0 {
+            instructions.push(Instruction::Move { amount: number });
+        }
+
+        Map { map, instructions, pos: pos.unwrap(), direction: Direction::Right }
+    }
+
+    fn opposite_position(&self, direction: Direction) -> Option<(isize,isize)> {
+        let mut old_pos = self.pos;
+        let mut old_object = Object::Floor;
+        loop {
+            let (x, y) = old_pos;
+            let check_pos = match direction {
+                Direction::Left => (x-1, y),
+                Direction::Right => (x+1, y),
+                Direction::Up => (x, y-1),
+                Direction::Down => (x, y+1),
+            };
+            match self.map.get(&check_pos) {
+                None => return match old_object {
+                    Object::Floor => Some(old_pos),
+                    Object::Wall => None,
+                },
+                Some(obj) => old_object = *obj,
+            }
+            old_pos = check_pos;
+        }
+    }
+
+    fn step_forward(&self) -> (isize,isize) {
+        let (x, y) = self.pos;
+        return match self.direction {
+            Direction::Left => {
+                match self.map.get(&(x-1,y)) {
+                    None => self.opposite_position(Direction::Right).unwrap_or(self.pos),
+                    Some(Object::Wall) => self.pos,
+                    Some(Object::Floor) => (x-1,y),
+                }
+            },
+            Direction::Right => {
+                match self.map.get(&(x+1,y)) {
+                    None => self.opposite_position(Direction::Left).unwrap_or(self.pos),
+                    Some(Object::Wall) => self.pos,
+                    Some(Object::Floor) => (x+1,y),
+                }
+            },
+            Direction::Up => {
+                match self.map.get(&(x,y-1)) {
+                    None => self.opposite_position(Direction::Down).unwrap_or(self.pos),
+                    Some(Object::Wall) => self.pos,
+                    Some(Object::Floor) => (x,y-1),
+                }
+            },
+            Direction::Down => {
+                match self.map.get(&(x,y+1)) {
+                    None => self.opposite_position(Direction::Up).unwrap_or(self.pos),
+                    Some(Object::Wall) => self.pos,
+                    Some(Object::Floor) => (x,y+1),
+                }
+            },
+        }
+    }
+
+    fn run(&mut self) {
+        for instruction in &self.instructions {
+            match instruction {
+                Instruction::Left => {
+                    self.direction = self.direction.turn_left();
+                },
+                Instruction::Right => {
+                    self.direction = self.direction.turn_right();
+                },
+                Instruction::Move { amount } => {
+                    for _ in 0 .. *amount {
+                        self.pos = self.step_forward();
+                    }
+                },
+            }
+        }
+    }
+
+    fn password(&self) -> isize {
+        let facing = match self.direction {
+            Direction::Right => 0,
+            Direction::Down => 1,
+            Direction::Left => 2,
+            Direction::Up => 3,
+        };
+        1000 * (self.pos.1 + 1) + 4 * (self.pos.0 + 1) + facing
+    }
+}
+
+fn find_password(input: &[String]) -> isize {
+    let mut map = Map::new(input);
+    map.run();
+    map.password()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = [
+            "        ...#",
+            "        .#..",
+            "        #...",
+            "        ....",
+            "...#.......#",
+            "........#...",
+            "..#....#....",
+            "..........#.",
+            "        ...#....",
+            "        .....#..",
+            "        .#......",
+            "        ......#.",
+            "",
+            "10R5L5R10L4R5L5",
+        ].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
+
+        assert_eq!(find_password(&input), 6032);
+    }
+}