2026-rff_mp/MusinAA/task2/strategyObjects/BFS.py

from task2.strategyObjects.pathFindingStrategy import PathFindingStrategy

from task2.mazeObjects.maze import Maze
from task2.mazeObjects.cell import Cell

import queue

class BFS(PathFindingStrategy):
    """Поиск в ширину – гарантирует кратчайший путь по количеству шагов.
    Возвращает None, если пути нет"""
    def findPath(self, maze: Maze, start: Cell, exit: Cell):
        visited = dict()
        parents = dict()
        q = queue.Queue()

        q.put(start)
        visited[start] = 0
        parents[start] = None

        while not q.empty():
            current = q.get()

            # Условие нахождение выхода
            if current == exit: break

            # Перебор соседей
            for hood in maze.getNeighbors(current):
                if hood in visited:
                    continue
                visited[hood] = visited[current] + 1
                parents[hood] = current
                q.put(hood)
        return self.restorePath(parents, start, exit)

    def restorePath(self, parents: dict, start: Cell, exit: Cell) -> list[Cell]|None:
        path = []
        current = exit
        while current:
            path.append(current)
            if current not in parents:
                return None
            current = parents[current]
        return path[::-1]