90. Subsets II

public class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<List<Integer>> res=new ArrayList<List<Integer>>();
        Arrays.sort(nums);
        subsetsWithDup(0, new ArrayList<Integer>(), res, nums);
        return res;
    }
    private void subsetsWithDup(int idx, List<Integer> list, List<List<Integer>> res, int[] nums){
        res.add(new ArrayList<Integer>(list));
        for(int i=idx;i<nums.length;i++)
        {
            if(i!=idx&&nums[i]==nums[i-1])
                continue;
            list.add(nums[i]);
            subsetsWithDup(i+1,list,res,nums);
            list.remove(list.size()-1);
        }
    }
}