[leetCode] Subsets

Given a set of distinct integers, nums, return all possible subsets.

Note:

• Elements in a subset must be in non-descending order.
• The solution set must not contain duplicate subsets.

For example,
If nums = [1,2,3], a solution is:

[  [3],  [1],  [2],  [1,2,3],  [1,3],  [2,3],  [1,2],  []]

public class Solution {    List<List<Integer>> res = new ArrayList<List<Integer>>();    public List<List<Integer>> subsets(int[] nums) {        Arrays.sort(nums);        List<Integer> item = new ArrayList<Integer>();        res.add(item);        sub(nums, 0, item);        return res;    }    private void sub(int[] nums, int index, List<Integer> input) {        for (int i = index; i < nums.length; i++) {            List<Integer> item = new ArrayList<Integer>(input);            item.add(nums[i]);            res.add(item);            sub(nums, i + 1, item);        }    }}