1  use std::{collections::HashSet, str};
  2  
  3  #[derive(Debug, PartialEq, Eq, Clone, Copy)]
  4  enum Tile {
  5      Obstacle,
  6      Void,
  7  }
  8  
  9  fn main() {
 10      let input = str::from_utf8(include_bytes!("input")).unwrap();
 11      let mut map: Vec<Vec<Tile>> = vec![];
 12      let mut guard: (i32, i32) = (0, 0);
 13      let mut guard_2: (i32, i32) = (0, 0);
 14      for (i, line) in input.lines().enumerate() {
 15          let mut new_line: Vec<Tile> = vec![];
 16          for (j, r#char) in line.chars().enumerate() {
 17              match r#char {
 18                  '#' => new_line.push(Tile::Obstacle),
 19                  '^' => {
 20                      guard = (i as i32, j as i32);
 21                      guard_2 = (i as i32, j as i32);
 22                      new_line.push(Tile::Void)
 23                  }
 24                  _ => new_line.push(Tile::Void),
 25              }
 26          }
 27          map.push(new_line);
 28      }
 29      let mut positions: HashSet<(i32, i32)> = HashSet::new();
 30      positions.insert((guard.0, guard.1));
 31      let mut guard_vec: (i32, i32) = (-1, 0);
 32      'game: loop {
 33          if 0 <= guard.0 + guard_vec.0
 34              && guard.0 + guard_vec.0 < map.len() as i32
 35              && 0 <= guard.1 + guard_vec.1
 36              && guard.1 + guard_vec.1 < map[0].len() as i32
 37          {
 38              match map[(guard.0 + guard_vec.0) as usize][(guard.1 + guard_vec.1) as usize] {
 39                  Tile::Obstacle => match guard_vec {
 40                      (0, 1) => guard_vec = (1, 0),
 41                      (1, 0) => guard_vec = (0, -1),
 42                      (0, -1) => guard_vec = (-1, 0),
 43                      (-1, 0) => guard_vec = (0, 1),
 44                      _ => todo!(),
 45                  },
 46                  Tile::Void => {
 47                      guard.0 += guard_vec.0;
 48                      guard.1 += guard_vec.1;
 49                      positions.insert((guard.0, guard.1));
 50                  }
 51              }
 52          } else {
 53              break 'game;
 54          }
 55      }
 56      println!("Part 1 : {}", positions.len());
 57      let mut sum = 0;
 58      for i in 0..*(&map.len()) {
 59          for j in 0..*(&map[0].len()) {
 60              let mut guard: (i32, i32) = guard_2;
 61              if map[i][j] == Tile::Obstacle || i as i32 == guard.0 && j as i32 == guard.1 {
 62                  continue;
 63              }
 64              let mut map_copy: Vec<Vec<Tile>> = map.clone();
 65              map_copy[i][j] = Tile::Obstacle;
 66              let mut positions: HashSet<((i32, i32), (i32, i32))> = HashSet::new();
 67              let mut guard_vec: (i32, i32) = (-1, 0);
 68              'game: loop {
 69                  if positions.contains(&(guard, guard_vec)) {
 70                      sum += 1;
 71                      break 'game;
 72                  }
 73                  if 0 <= guard.0 + guard_vec.0
 74                      && guard.0 + guard_vec.0 < map_copy.len() as i32
 75                      && 0 <= guard.1 + guard_vec.1
 76                      && guard.1 + guard_vec.1 < map_copy[0].len() as i32
 77                  {
 78                  positions.insert((guard, guard_vec));
 79                      match map_copy[(guard.0 + guard_vec.0) as usize]
 80                          [(guard.1 + guard_vec.1) as usize]
 81                      {
 82                          Tile::Obstacle => {
 83                              match guard_vec {
 84                                  (0, 1) => guard_vec = (1, 0),
 85                                  (1, 0) => guard_vec = (0, -1),
 86                                  (0, -1) => guard_vec = (-1, 0),
 87                                  (-1, 0) => guard_vec = (0, 1),
 88                                  _ => todo!(),
 89                              }
 90                          }
 91                          Tile::Void => {
 92                              guard.0 += guard_vec.0;
 93                              guard.1 += guard_vec.1;
 94                          }
 95                      }
 96                  } else {
 97                      break 'game;
 98                  }
 99              }
100          }
101      }
102      println!("Part 2 : {}", sum);
103  }