这段 杨辉三角 的算法，真漂亮...

[Tiande]

来源 (代码在评论中)

代码：

def triangles():
....a = [1];
....while True:
........yield a
........a = [sum(i) for i in zip([0] + a, a + [0])]


部分结果：

$ python python/pytest.py
[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]

真是爆za了 ;)

[yuankui]

好多列表的concat

[wizardoz]

@xuyl
for i,l in zip(range(10),triangles()):
....print(l)

[forrestchang]

刚学Swift, 用Swift写了一个，基本的方法
func pascalsTriangle(rows: Int) {
if rows < 0 {
return
}

var last = [Int]()
last.append(1)
println(last)

for i in 1..<rows {
var thisRow = [Int]()
thisRow.append(last.first!)
for j in 1..<i {
thisRow.append(last[j - 1] + last[j])
}
thisRow.append(last.first!)
last = thisRow
println(thisRow)
}

}

[shizukoto]

JavaScript (ES6) 实现：

```js
const {zip, sum, map, head} = require('aureooms-js-itertools');

function *triangles() {
let a = [1];
while (true) {
yield a;
a = Array.from(map(sum, zip([[0].concat(a), a.concat([0])])));
}
}

for (let row of head(triangles(), 5)) console.log(row.join(' '));

```

[Hchan]

lazy val tri: Stream[List[Int]] = List(1) #:: tri map {s => (0 :: (s :+ 0)).sliding(2).toList.map(_.sum)}
@lds56