递归[网格中的机器人] Python中的列表更新错误

def find_path(grid, robot, x, y, path):
    if x < 0 or x >= len(grid) or y < 0 or y >= len(grid[0]) or grid[x][y] == 1:
        return False

    if (x, y) == robot:
        return True

    # 标记当前位置为已访问
    temp = grid[x][y]
    grid[x][y] = 1

    path.append((x, y))

    # 递归查找路径
    if (find_path(grid, robot, x+1, y, path) or
        find_path(grid, robot, x-1, y, path) or
        find_path(grid, robot, x, y+1, path) or
        find_path(grid, robot, x, y-1, path)):
        return True

    # 回溯
    path.pop()
    grid[x][y] = temp

    return False

def get_path(grid, robot):
    path = []
    if find_path(grid, robot, 0, 0, path):
        return path
    else:
        return None