python如何实现杨辉三角形（代码）

 1
 / 
 1 1
 / / 
 1 2 1
 / / / 
 1 3 3 1
 / / / / 
 1 4 6 4 1
 / / / / / 
1 5 10 10 5 1

def triangles():
 L = [1]
 while True:
 yield L
 
 M=L[:]#复制一个list，这样才不会影响到原有的list。不然results里的每个列表的末尾会为0.
 M.append(0)
 L = [M[i-1]+M[i] for i in range(len(M))] 
 
n =0
results = []
for t in triangles():
 
 print(t)
 results.append(t)
 print(results)
 n = n +1
 if n == 10:
 break