added TurtleDFS.py
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Project 5/TurtleDFS.py
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256
Project 5/TurtleDFS.py
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######################################
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# DCS 229 -- Turtle DFS
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# Non-recursive depth first search for solving turtle mazes
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# Date: 03/29/2026
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# Name: Benjamin Adovasio
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# Resources Used: Project 5 handout and TurtleMaze.py
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##########################################
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from __future__ import annotations
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from pathlib import Path
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import sys
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from types import SimpleNamespace
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from Stack import Stack
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try:
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import turtle
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TURTLE_AVAILABLE = True
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except ModuleNotFoundError:
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TURTLE_AVAILABLE = False
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class _StubTerminator(Exception):
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"""Fallback replacement for turtle.Terminator."""
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class _StubScreen:
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def setworldcoordinates(self, *args) -> None:
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pass
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def tracer(self, *args) -> None:
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pass
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def update(self) -> None:
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pass
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def mainloop(self) -> None:
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pass
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class _StubTurtle:
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def __init__(self):
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self.screen = _StubScreen()
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def shape(self, *args) -> None:
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pass
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def speed(self, *args) -> None:
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pass
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def up(self) -> None:
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pass
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def goto(self, *args) -> None:
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pass
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def color(self, *args) -> None:
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pass
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def fillcolor(self, *args) -> None:
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pass
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def setheading(self, *args) -> None:
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pass
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def down(self) -> None:
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pass
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def begin_fill(self) -> None:
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pass
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def forward(self, *args) -> None:
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pass
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def right(self, *args) -> None:
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pass
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def end_fill(self) -> None:
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pass
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def dot(self, *args) -> None:
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pass
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def towards(self, *args) -> int:
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return 0
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turtle = SimpleNamespace(
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Turtle=_StubTurtle,
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Screen=_StubScreen,
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Terminator=_StubTerminator,
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)
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sys.modules["turtle"] = turtle
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from TurtleMaze import Cell, Contents, TurtleMaze
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class TestMaze:
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"""Lightweight maze implementation used for non-GUI testing."""
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def __init__(self, maze_file_name: str | Path):
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self.maze_grid: list[list[Cell]] = []
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self._path_log: list[tuple[int, int, Contents | None]] = []
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maze_path = Path(maze_file_name)
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for row_index, line in enumerate(maze_path.read_text().splitlines()):
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row_list: list[Cell] = []
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for col_index, char in enumerate(line):
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cell = Cell(row_index, col_index, Contents(char))
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row_list.append(cell)
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if cell._contents == Contents.START:
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self._start = cell
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if cell._contents == Contents.GOAL:
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self._goal = cell
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self.maze_grid.append(row_list)
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def updatePosition(self, cell: Cell, val: Contents | None = None) -> None:
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"""Track visited positions during tests without opening a turtle window."""
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if val is not None:
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cell._contents = val
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self._path_log.append((cell.x, cell.y, val))
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def getStart(self) -> Cell:
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return self._start
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def getGoal(self) -> Cell:
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return self._goal
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def __getitem__(self, idx: int) -> list[Cell]:
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return self.maze_grid[idx]
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def get_neighbors(maze: TurtleMaze, cell: Cell) -> list[Cell]:
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"""Return each non-obstacle neighbor in north, south, east, west order."""
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neighbors: list[Cell] = []
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candidate_positions = (
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(cell.y - 1, cell.x), # north
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(cell.y + 1, cell.x), # south
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(cell.y, cell.x + 1), # east
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(cell.y, cell.x - 1), # west
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)
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for row, col in candidate_positions:
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if 0 <= row < len(maze.maze_grid) and 0 <= col < len(maze[row]):
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neighbor = maze[row][col]
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if not neighbor.isBlocked():
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neighbors.append(neighbor)
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return neighbors
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def _mark_solution_path(maze: TurtleMaze, goal: Cell) -> None:
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"""Walk the successful route without teleporting and color it green."""
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goal_to_start: list[Cell] = []
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current: Cell | None = goal
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while current is not None:
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goal_to_start.append(current)
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current = current.getParent()
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for cell in goal_to_start:
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maze.updatePosition(cell, Contents.PART_OF_PATH)
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for cell in reversed(goal_to_start[:-1]):
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maze.updatePosition(cell, Contents.PART_OF_PATH)
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def dfs(maze: TurtleMaze) -> bool:
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"""Solve a maze using a non-recursive depth first search."""
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start = maze.getStart()
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stack: Stack[Cell] = Stack()
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visited: set[tuple[int, int]] = set()
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stack.push(start)
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visited.add((start.x, start.y))
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maze.updatePosition(start, Contents.TRIED)
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while not stack.is_empty():
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current = stack.peek()
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if current.isGoal():
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_mark_solution_path(maze, current)
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return True
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next_cell = None
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for neighbor in get_neighbors(maze, current):
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coordinates = (neighbor.x, neighbor.y)
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if coordinates not in visited:
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neighbor.setParent(current)
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next_cell = neighbor
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break
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if next_cell is not None:
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visited.add((next_cell.x, next_cell.y))
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stack.push(next_cell)
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if next_cell.isGoal():
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maze.updatePosition(next_cell)
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else:
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maze.updatePosition(next_cell, Contents.TRIED)
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continue
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dead_end = stack.pop()
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if dead_end != start and not dead_end.isGoal():
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maze.updatePosition(dead_end, Contents.DEAD_END)
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if not stack.is_empty():
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maze.updatePosition(stack.peek())
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return False
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def _project_path(file_name: str) -> Path:
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"""Return a path inside the Project 5 directory."""
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return Path(__file__).resolve().with_name(file_name)
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def _test_get_neighbors() -> None:
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maze = TestMaze(_project_path("maze_1.txt"))
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start = maze.getStart()
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neighbor_coordinates = [(cell.x, cell.y) for cell in get_neighbors(maze, start)]
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assert neighbor_coordinates == [(5, 1), (3, 1)]
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def _test_dfs() -> None:
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for maze_name in ("maze_1.txt", "maze_2.txt", "maze_3.txt"):
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maze = TestMaze(_project_path(maze_name))
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solved = dfs(maze)
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assert solved is True
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assert maze.getStart()._contents == Contents.PART_OF_PATH
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assert maze.getGoal()._contents == Contents.PART_OF_PATH
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def main() -> None:
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_test_get_neighbors()
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_test_dfs()
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print("All TurtleDFS tests passed.")
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if not TURTLE_AVAILABLE:
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print("Skipping turtle visualization: turtle graphics are unavailable in this Python environment.")
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return
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maze_path = _project_path("maze_2.txt")
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try:
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maze = TurtleMaze(str(maze_path))
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maze.drawMaze()
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solved = dfs(maze)
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print(f"Visual DFS demo on {maze_path.name}: {solved}")
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maze.t.screen.mainloop()
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except Exception as err:
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print(f"Skipping turtle visualization: {err}")
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if __name__ == "__main__":
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main()
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