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廖雪峰 python教程
生成器章节，有一道杨辉的题目。
杨辉三角定义如下：
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
把每一行看做一个list，试写一个generator，不断输出下一行的list：
def triangles():
L=[1]
while True:
yield L
L.append(0)
L = [L[i-1]+L[i] for i in range(len(L))]
# 期待输出:
# [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]
n = 0
for t in triangles():
print(t)
n = n + 1
if n == 10:
break
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