/*
 * @lc app=leetcode.cn id=78 lang=golang
 *
 * [78] 子集
 */

// @lc code=start
func subsets(nums []int) (res [][]int) {
	res = append(res, make([]int, 0))
	var combine func(nums []int, k int) (ans [][]int)
	combine = func(nums []int, k int) (ans [][]int) {
		if k == 1 {
			for i := 0; i < len(nums); i++ {
				ans = append(ans, []int{nums[i]})
			}
			return
		}
		for i := 0; i < len(nums); i++ {
			temp := combine(nums[i+1:], k-1)
			for _, v := range temp {
				ans = append(ans, append([]int{nums[i]}, v...))
			}
		}
		return
	}

	for i := 1; i <= len(nums); i++ {
		res = append(res, combine(nums, i)...)
	}
	return
}

// @lc code=end