-----杨辉三角

# [1]
# [1, 1]
# [1, 2, 1]
# [1, 3, 3, 1]
# [1, 4, 6, 4, 1]
# [1, 5, 10, 10, 5, 1]
# [1, 6, 15, 20, 15, 6, 1]
# [1, 7, 21, 35, 35, 21, 7, 1]
# [1, 8, 28, 56, 70, 56, 28, 8, 1]
# [1, 9, 36, 84, 126, 126, 84, 36, 9, 1]def triangles():L=[1]#第一行为1 初始数据设定为[1]while True:yield L#第二行数据中间部分range(len(L)-1)不满足条件因此不执行，所以刚好是[1,1]L=[1]+[L[i] + L[i+1] for i in range(len(L)-1)]+[1]#从第三行开始中间的部分数据等于上一行数据前两位的和
m=0
for x in triangles():print(x)m=m+1if m==20:break