Mouse Searches Cheese in Labyrinth

mouse_searches_cheese.py

from typing import NamedTuple, Optional
from enum import Enum


class Dir(Enum):
    Up = 0
    Right = 1
    Down = 2
    Left = 3

REVERSE_DIR_MAP = {
    Dir.Up: Dir.Down,
    Dir.Right: Dir.Left,
    Dir.Down: Dir.Up,
    Dir.Left: Dir.Right
}


class Coordinate(NamedTuple):
    y:int
    x:int

    def goto(self, dir):
        if dir == Dir.Up:
            return Coordinate(self.y - 1, self.x)
        elif dir == Dir.Right:
            return Coordinate(self.y, self.x + 1)
        elif dir == Dir.Down:
            return Coordinate(self.y + 1, self.x)
        elif dir == Dir.Left:
            return Coordinate(self.y, self.x - 1)


class Maze:
    
    def __init__(self, maze:str):
        self.maze = [l.strip() for l in maze.strip().splitlines()]
    
    def can_goto(self, coord:Coordinate, dir:Dir):
        if dir == Dir.Up:
            return self.maze[coord.y-1][coord.x] not in ('_', 'L')
        elif dir == Dir.Right:
            return self.maze[coord.y][coord.x+1] not in ('|', 'L')
        elif dir == Dir.Down:
            return self.maze[coord.y][coord.x] not in ('_', 'L')
        elif dir == Dir.Left:
            return self.maze[coord.y][coord.x] not in ('|', 'L')

    @property
    def height(self):
        return len(self.maze)

    @property
    def width(self):
        return len(self.maze[0])
    

class Mouse:

    def __init__(self, maze:Maze, start:Coordinate):
        self.maze = maze
        self.coord = start
        self.enter_dir = None
        self.memory = [[None]*maze.width for i in range(maze.height)]
        self.memory[start.y][start.x] = Dir.Down    # mark as visited

    def get_first_visit(self, coord:Coordinate) -> Optional[Dir]:
        return self.memory[coord.y][coord.x]

    def move(self) -> Dir:
        free_dirs = [ dir for dir in Dir if self.maze.can_goto(self.coord,dir) ]
        unvisited_dirs = [ dir for dir in free_dirs
                           if not self.get_first_visit(self.coord.goto(dir)) ]
        if unvisited_dirs:
            dir = self.enter_dir = unvisited_dirs.pop()
            self.coord = self.coord.goto(dir)
            self.memory[self.coord.y][self.coord.x] = REVERSE_DIR_MAP[dir]
        else:
            dir = self.get_first_visit(self.coord)
            self.coord = self.coord.goto(dir)
        return dir


if __name__ == '__main__':
    maze = Maze("""
                ___________
                |   L__ | |
                |||___ ||||
                L__ L____||
                L_________|
                """)
    cheese = Coordinate(2, 1)
    mouse = Mouse(maze, Coordinate(1, 0))
    while mouse.coord != cheese:
        dir = mouse.move()
        print(f"{dir:10} => {mouse.coord}")