Python 杨辉三角

 第1,2种方法没法使用 yield.在递归中, 函数内部使用yield, 均会使该函数运行一次就退出.不再递归.

def fun(x, li=[1], n=1):
	if n == x+1:
		return li, sum(li)
	li.insert(0, 0)
	li.append(0)
	l = []
	for i in range(n):
		l.append(li[i] + li[i+1])
	li.pop(0)
	li.pop(-1)
	return fun(x,l, n+1)

f = fun(4)
print(f)

　　

def fun(n, li =None):
	if not isinstance(li, list):
		li = []
	if n == 0:
		return 0
	l = []
	for i in range (len(li)+1):
		if 0 < i and i < len(li):
			x = li[i] + li[i-1]
		else:
			x = 1
		l.append(x)
	print(l)
	fun(n-1, l)

f = fun(5)

　　

def fun():
	li, l  = [], []
	while not l:
		for i in range (len(li)+1):
			if 0 < i and i < len(li):
				x = li[i] + li[i-1]
			else:
				x = 1
			l.append(x)
		li, l = l, []
		yield li

ff = fun()
n = 0
for f in ff:
	print(f)
	n += 1
	if n > 10:
		break