杨辉三角形式如下：
          1        1   1      1   2   1    1   3   3   1  1   4   6   4   11   5   10  10  5   1    

# 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 = 0for t in triangles():    print(t)    n = n + 1    if n == 10:        break

思路：1、第i-1行最后补0，将长度与第i行保持一致；2、第i行第n个元素值为L(i)[n] = L(i-1)[n-1]+L(i-1)[n]例如：1、i=3时，此时集合为[1,3,3,1]；2、i-1行集合补0后，集合为[1,2,1,0]3、L(3)[0]=L(2)[-1]+L(2)[0]=0+1=1     L(3)[1]=L(2)[0]+L(2)[1]=1+2=3     .....

代码如下：def triangles():    L = [1]    while True:        yield L        L.append(0)        L = [L[i - 1] + L[i] for i in range(len(L))]n=0for t in triangles():    print(t)    n = n + 1    if n == 10:        break