要注意返回的值的类型是不是tuple

def findMinAndMax(L):

    min=0

    max=0

    if len(L)==0:

        return tuple([None,None])

    else:

        for i in L:

            for j in L:

                if i>=j:

                    i=j

                min=i  #找出最小值

        for i in L:

            for j in L:

                if i<=j:

                    i=j

                max=i  #找出最大值

        return tuple([min,max])

# 测试

if findMinAndMax([]) != (None, None):

    print('测试失败!')

elif findMinAndMax([7]) != (7, 7):

    print('测试失败!')

elif findMinAndMax([7, 1]) != (1, 7):

    print('测试失败!')

elif findMinAndMax([7, 1, 3, 9, 5]) != (1, 9):

    print('测试失败!')

else:

    print('测试成功!')