python 杨辉三角

嗯呢,不太会写注释之类的,反正就是…
有一行吧是这样的

l= [1,3,3,1]

然后就分成2行,[0]+l 和 l+[0]
然后竖着加

[0 , 1 , 3 , 3 , 1]
+
[1 , 3 , 3 , 1 , 0]
=
[1 , 4 , 6 , 4 , 0]

下一行就出来了

def func(n):
    lis = [[1]]
    
    for n in range(n-1):
        a = [0]+ lis[-1]
        b = lis[-1]+[0]
        lis.append([ a[_]+b[_] for _ in range(len(a)) ])
        
    return lis

---

效果呢,这里

from pprint import pprint

r = func(10)

pprint(r)

[[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]]