def findMinAndMax(L):
    if L==[]:
        return (None,None)
    else:
        minL=L[0]
        maxL=L[0]
        for value in L:
            if minL>=value:
                minL=value
            if maxL<=value:
                maxL=value
        return (minL,maxL)
 
 
 
 
 
# 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!')

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