def findMinAndMax(L):

if len(L) == 0:
    return(None, None)
elif len(L) == 1:
    return(L[0], L[0])


else:
    min1 = L[0]
    max1 = L[0]
    for i in L:
        if i <= min1:
            min1 = i
        if i >= max1:
            max1 = i


    return(min1,max1)

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!')