feat: add the algorithm to solve the maze

cell.py

@@ -4,7 +4,7 @@ from graphics import Window, Point, Line
 import errors
 
 
-class CellWallLabel(Enum):
+class CellWallLabels(Enum):
     """
     CellWallLabel is used to label a CellWall
     """
@@ -61,11 +61,11 @@ class Cell:
         left_wall = Line(Point(x1, y1), Point(x1, y2))
         right_wall = Line(Point(x2, y1), Point(x2, y2))
 
-        self._walls: Dict[CellWallLabel, CellWall] = {
-            CellWallLabel.TOP: CellWall(top_wall, window),
-            CellWallLabel.BOTTOM: CellWall(bottom_wall, window),
-            CellWallLabel.LEFT: CellWall(left_wall, window),
-            CellWallLabel.RIGHT: CellWall(right_wall, window),
+        self._walls: Dict[CellWallLabels, CellWall] = {
+            CellWallLabels.TOP: CellWall(top_wall, window),
+            CellWallLabels.BOTTOM: CellWall(bottom_wall, window),
+            CellWallLabels.LEFT: CellWall(left_wall, window),
+            CellWallLabels.RIGHT: CellWall(right_wall, window),
         }
 
         # Calculate the cell's central point
@@ -90,13 +90,13 @@ class Cell:
         configure_walls configures the existence of the Cell's walls.
         """
         if top is not None:
-            self._walls[CellWallLabel.TOP].exists = top
+            self._walls[CellWallLabels.TOP].exists = top
         if bottom is not None:
-            self._walls[CellWallLabel.BOTTOM].exists = bottom
+            self._walls[CellWallLabels.BOTTOM].exists = bottom
         if left is not None:
-            self._walls[CellWallLabel.LEFT].exists = left
+            self._walls[CellWallLabels.LEFT].exists = left
         if right is not None:
-            self._walls[CellWallLabel.RIGHT].exists = right
+            self._walls[CellWallLabels.RIGHT].exists = right
 
     def centre(self) -> Point:
         """
@@ -104,10 +104,14 @@ class Cell:
         """
         return self._centre
 
-    def wall_exists(self, wall: CellWallLabel) -> bool:
+    def wall_exists(self, wall: CellWallLabels) -> bool:
         """
         returns True if a given cell wall exists, or false otherwise.
         """
+        if wall not in CellWallLabels:
+            raise TypeError(
+                "The argument does not appear to be a valid cell wall."
+            )
         return self._walls[wall].exists
 
     def draw(self) -> None:
@@ -117,7 +121,7 @@ class Cell:
         if not self._window:
             return
 
-        for label in CellWallLabel:
+        for label in CellWallLabels:
             self._walls[label].draw()
 
     def draw_move(self, to_cell: 'Cell', undo: bool = False) -> None:

main.py

@@ -5,7 +5,7 @@ from maze import Maze
 def main():
     window = Window(800, 800)
 
-    _ = Maze(
+    game = Maze(
         x_position=10,
         y_position=10,
         num_cell_rows=30,
@@ -15,6 +15,12 @@ def main():
         window=window
     )
 
+    solved = game.solve()
+    if solved:
+        print("Maze solved successfully :)")
+    else:
+        print("I'm unable to solve the maze :(")
+
     window.mainloop()
 
 

maze.py

@@ -1,9 +1,9 @@
-from typing import List
+from typing import List, Dict
 from time import sleep
 import random
 from enum import Enum
 from graphics import Window
-from cell import Cell
+from cell import Cell, CellWallLabels
 
 
 class MazeDirections(Enum):
@@ -39,7 +39,7 @@ class MazePosition:
     ) -> 'MazePosition':
         if direction not in MazeDirections:
             raise TypeError(
-                "The argument does not appear to be a valid MazeDirection"
+                "The argument does not appear to be a valid maze direction."
             )
 
         if direction is MazeDirections.ABOVE and (self.i-1 >= 0):
@@ -105,6 +105,8 @@ class Maze:
         self._cells: List[List[Cell]] = [
             None for i in range(self._num_cell_rows)]
         self._create_cell_grid()
+
+        # Open up the maze's entrance and exit.
         self._open_entrance_and_exit()
 
         start_position = MazePosition(
@@ -114,13 +116,7 @@ class Maze:
             max_j=self._num_cells_per_row-1,
         )
 
-        end_position = MazePosition(
-            i=self._num_cell_rows-1,
-            j=self._num_cells_per_row-1,
-            max_i=self._num_cell_rows-1,
-            max_j=self._num_cells_per_row-1,
-        )
-
+        # Generate the maze.
         self._break_walls_r(start_position)
 
     def _create_cell_grid(self) -> None:
@@ -227,6 +223,59 @@ class Maze:
 
             self._break_walls_r(next_position)
 
+    def solve(self) -> bool:
+        """
+        solve attempts to solve the generated maze.
+        """
+        start_position = MazePosition(
+            i=0,
+            j=0,
+            max_i=self._num_cell_rows-1,
+            max_j=self._num_cells_per_row-1,
+        )
+
+        end_position = MazePosition(
+            i=self._num_cell_rows-1,
+            j=self._num_cells_per_row-1,
+            max_i=self._num_cell_rows-1,
+            max_j=self._num_cells_per_row-1,
+        )
+
+        return self._solve_r(start_position, end_position)
+
+    def _solve_r(
+            self,
+            current_position: MazePosition,
+            end_position: MazePosition,
+    ) -> bool:
+        if current_position == end_position:
+            return True
+        current_cell = self._cells[current_position.i][current_position.j]
+        current_cell.visited_by_maze_solver = True
+
+        wall_map: Dict[MazeDirections, CellWallLabels] = {
+            MazeDirections.ABOVE: CellWallLabels.BOTTOM,
+            MazeDirections.BELOW: CellWallLabels.TOP,
+            MazeDirections.LEFT: CellWallLabels.RIGHT,
+            MazeDirections.RIGHT: CellWallLabels.LEFT,
+        }
+
+        for direction in MazeDirections:
+            adjacent_position = current_position.get_adjacent_position(
+                direction)
+            if adjacent_position is None:
+                continue
+            adjacent_cell = self._cells[adjacent_position.i][adjacent_position.j]
+            if adjacent_cell.visited_by_maze_solver or adjacent_cell.wall_exists(wall_map[direction]):
+                continue
+            self._draw_path(current_cell, adjacent_cell)
+            result = self._solve_r(adjacent_position, end_position)
+            if result is True:
+                return True
+            self._draw_path(current_cell, adjacent_cell, undo=True)
+
+        return False
+
     def _draw_cell(self, i: int, j: int) -> None:
         """
         _draw_cell draws the cells in an animated way.
@@ -234,3 +283,8 @@ class Maze:
         self._cells[i][j].draw()
         self._window.redraw()
         sleep(0.05)
+
+    def _draw_path(self, current_cell: Cell, next_cell: Cell, undo: bool = False) -> None:
+        current_cell.draw_move(next_cell, undo)
+        self._window.redraw()
+        sleep(0.05)

tests.py

@@ -1,5 +1,5 @@
 import unittest
-from cell import Cell, CellWallLabel
+from cell import Cell, CellWallLabels
 import maze
 import errors
 
@@ -65,10 +65,10 @@ class Tests(unittest.TestCase):
             None,
             None,
         )
-        self.assertFalse(m._cells[0][0].wall_exists(CellWallLabel.TOP))
+        self.assertFalse(m._cells[0][0].wall_exists(CellWallLabels.TOP))
         self.assertFalse(
             m._cells[number_of_cell_rows - 1]
-            [number_of_cells_per_row - 1].wall_exists(CellWallLabel.BOTTOM)
+            [number_of_cells_per_row - 1].wall_exists(CellWallLabels.BOTTOM)
         )
 
     def test_invalid_cell_exception(self):