LeetCode 78. Subsets

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

Note: 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],  []]

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输出给出的数组的全部子数组，一道np问题，暴力递归即可

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