Python 杨辉三角

Python 杨辉三角

通过生成器，实现杨辉三角

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

def triangles():
    N = [1]    # 初始化为[1],杨辉三角的每一行为一个list
    while True:
        yield N    # yield 实现记录功能，没有下一个next将跳出循环，
        S = N[:]    # 将list N赋给S，通过S计算每一行
        S.append(0)  # 将list添加0，作为最后一个元素，长度增加1
        N = [S[i - 1] + S[i] for i in range(len(S))]    # 通过S来计算得出N

# 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
results = []
for t in triangles():
    results.append(t)
    n = n + 1
    if n == 10:
        break

for t in results:
    print(t)

if results == [
    [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]
]:
    print('测试通过!')
else:
    print('测试失败!')