用生成器写一个杨辉三角

def yang_hui_san_jiao(num):

lists = [1,1]

yield [1]

yield lists

for i in range(num-2):

kong = []

for ii in range(len(lists)-1):

kong+=[lists[ii] + lists[ii+1]]

result = [1]+kong+[1]

yield result

lists = result

for i in yang_hui_san_jiao(20):

print(i)