LeetCode_78 Subsets

Link to original problem: 这里写链接内容
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],
[]
]

这题在背包问题集合中，需要考虑的事情不是很多。只需要及时将cur加入res中，而不是等进入下一个recursion以后才加入。算是简单题吧，直接贴代码了。

public class Solution {    public List<List<Integer>> subsets(int[] nums) {        List<List<Integer>> res = new ArrayList<List<Integer>>();        res.add(new ArrayList<Integer>());        if(nums == null || nums.length == 0) return res;        Arrays.sort(nums);        List<Integer> cur = new ArrayList<Integer>();        helper(res, cur, nums, 0);        return res;    }    private void helper(List<List<Integer>> res, List<Integer> cur, int[] nums, int start){        for(int ii = start; ii < nums.length; ii++){            cur.add(nums[ii]);            res.add(new ArrayList<Integer>(cur));            helper(res, cur, nums, ii+1);            cur.remove(cur.size()-1);        }    }}