Subsets II

Given a collection of integers that might contain duplicates, nums, return all possible subsets.

Note: The solution set must not contain duplicate subsets.

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

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

Solution:

public class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<List<Integer>> ans = new ArrayList<>();
        ans.add(new ArrayList<Integer>());
        Arrays.sort(nums);
        int size = ans.size();
        for(int i=0; i<nums.length; i++){
            List<List<Integer>> newAns = new ArrayList<>();
            if(i!=0 && nums[i]==nums[i-1]){
                for(int j=0; j<size; j++){
                    List<Integer> tmp = new ArrayList<>(ans.get(j));
                    tmp.add(nums[i]);
                    newAns.add(tmp);
                }
            } else {
                for(int j=0; j<ans.size(); j++){
                    List<Integer> tmp = new ArrayList<>(ans.get(j));
                    tmp.add(nums[i]);
                    newAns.add(tmp);
                }
                size = ans.size();
            }
            newAns.addAll(ans);
            ans = newAns;
        }
        return ans;
    }
}