杨辉三角-python

# -*- coding: utf-8 -*-

def triangles():

    yield [1]      # n = 0 第一行

    yield [1, 1]  # n = 1 第二行

    b, n, old = 0, 2, [1, 1] # 从第三行开始 n = 2

    newL = list(range(n + 1))

    while b < n:

        if b == 0:

            newL[0] = 1

        else:

            newL[b] = old[b] + old[b-1]

        b = b + 1

        if b == n:

            newL[n] = 1

            yield newL

            b, n, old = 0, n + 1, newL[::] # 初始化下一行需要的变量

            newL = list(range(n + 1))