python——杨辉三角

杨辉三角

 

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():
    t = [1]
    while True:
        yield t
        t = [1] + [t[n] + t[n + 1] for n in range(len(t) - 1)] + [1]

        
>>> n=0
>>> result=[]
>>> for t in triangles():
	result.append(t)
	n=n+1
	if n==10:
		break

	
>>> for t in result:
	print(t)

	
[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]