def findMinAndMax(L):

    if(len(L)==0):

        return (None,None)

    else:

        min=L[0]

        max=L[0]

        for x in L:

            if(x<min):

                min=x

        for y in L:

            if(y>max):

                max=y

        return (min,max)

# 测试

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

    print('1测试失败!')

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

    print('2测试失败!')

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

    print('3测试失败!')

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

    print('4测试失败!')

else:

    print('测试成功!')