矩阵路径(python)

m行n列的矩阵，从左上是起点，到右下的最短路径

def best_path(matrix):
    i = len(matrix)    # 行数
    j = len(matrix[0])  # 列数
    # 建立一个标志矩阵  代表着我们当前往哪里走
    direction = [[None for k in range(j)] for m in range(i)]
    direction[0][0] = '起点'
    for k in range(1, j):
        matrix[0][k] += matrix[0][k-1]
        direction[0][k] = '向左'
    for m in range(1, i):
        matrix[m][0] += matrix[m-1][0]
        direction[m][0] = '向上'
    for k in range(1, j):
        for m in range(1, i):
            temp = min(matrix[m-1][k], matrix[m][k-1])
            if temp == matrix[m][k-1]:
                direction[m][k] = '向左'
            if temp == matrix[m-1][k]:
                direction[m][k] = '向上'
            matrix[m][k] += temp
    for d in direction:
        print(d)
    return matrix, direction
def print_path(direction):
    path = []
    i = len(direction) -1
    j = len(direction[0])-1
    while i > 0 and j > 0:
        if direction[i][j] == '向左':
            j -= 1
            path.append('向左')
        if direction[i][j] == '向上':
            i -= 1
            path.append('向上')
    path.append('起点')
    return path
if __name__ == '__main__':
    matrix = [[2, 3, 1, 4, 4],
              [2, 1, 4, 5, 3],
              [3, 0, 2, 3, 6],
              [4, 3, 2, 0, 8],
              [4, 2, 0, 2, 1]]
    matrix_, direction = best_path(matrix)
 
    # 打印路径
    path = print_path(direction)
    print("从终点会起点的路径:", path)