二维数组中的每条可能路径？(叉积)

def findPaths(matrix):
    if not matrix or not matrix[0]:
        return []

    m, n = len(matrix), len(matrix[0])
    start = (0, 0)
    end = (m-1, n-1)
    paths = []
    path = []

    def backtrack(curr):
        if curr == end:
            paths.append(path[:])
            return

        x, y = curr
        directions = [(0, 1), (0, -1), (1, 0), (-1, 0)]  # 右、左、下、上
        for dx, dy in directions:
            nx, ny = x + dx, y + dy
            if 0 <= nx < m and 0 <= ny < n and matrix[nx][ny] != 0:
                path.append((nx, ny))
                matrix[nx][ny] = 0  # 标记已访问
                backtrack((nx, ny))
                matrix[nx][ny] = 1  # 恢复未访问状态
                path.pop()

    path.append(start)
    matrix[0][0] = 0  # 标记起点已访问
    backtrack(start)

    return paths