90

class Solution {
public:
    void backtrack(vector<vector<int>> &ans,vector<int> nums,vector<int> temp,int start){
        ans.push_back(temp);
        for(int i=start;i<nums.size();i++){
            if(i>start && nums[i]==nums[i-1]){
                continue;
            }
            temp.push_back(nums[i]);
            backtrack(ans,nums,temp,i+1);
            temp.pop_back();
        }
    }
    vector<vector<int>> subsetsWithDup(vector<int>& nums) {
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        sort(nums.begin(),nums.end());
        vector<vector<int>> ans;
        backtrack(ans,nums,{},0);
        return ans;
    }
};