sum = 0
x = 1
n = 1
while True:
sum=sum+x
x=x*2
n=n+1
if n==21:
break
print sum
x = 1
n = 1
while True:
sum=sum+x
x=x*2
n=n+1
if n==21:
break
print sum
2019-09-18
ss =['Adam', 'Lisa', 'Bart', 'Paul']
s = set(ss)
print s
s = set(ss)
print s
2019-09-18
or:
print(0 or 55) , 结果输出55
print(55 or 0), 结果输出55
print(None or 55) , 结果输出55
print(55 or None), 结果输出55
print('' or 55) , 结果输出55
print(55 or ''), 结果输出55
print(22 or 55) , 结果输出22
print(55 or 22), 结果输出55
print(0 or 55) , 结果输出55
print(55 or 0), 结果输出55
print(None or 55) , 结果输出55
print(55 or None), 结果输出55
print('' or 55) , 结果输出55
print(55 or ''), 结果输出55
print(22 or 55) , 结果输出22
print(55 or 22), 结果输出55
2019-09-17