Kie

``` javascript /* *返回arr的所有长度为size的子数组的组合 * 如arr = [1,2,3,4], size = 2 * return [[1,2], [1,3], [1,4], [2,3], [2,4], [3,4]] * * 再如arr = [1,2,3,4], size = 3 * return [[1,2,3],...