python实现裴波那契数列

def Fib(n):
    '''
    假定序号为0或者1,返回1,序号为2时返回2
    '''
    before = 1
    after = 1
    for i in range(n):
        before, after = after, before + after
    return before

for i in range(10):
    print(Fib(i)) 

用生成器实现如下:

def fib(n):
    before = 1
    after = 1
    for i in range(n):
        yield before
        before, after = after, before + after

gen = fib(6)
for i in gen:
    print(i)