//decision is to include the repeated element how many times, 0,1,2,..

void helper(vector<int> &nums,int startIdx, vector<vector<int>> &res,vector<int> currSet){

//base case

int n= nums.size();

if (startIdx==n){

res.push_back(currSet);

return;

}

//recursive case

int i,j;

i= startIdx+1;

//find the non-repeating index

while (i<n && nums[i]==nums[i-1]) i++;

j=i;

//include

helper(nums,j,res,currSet);

//more than 1 times

for (i=startIdx;i<j;i++){

currSet.push_back(nums[i]);

helper(nums,j,res,currSet);

}

}

vector<vector<int>> subsetsWithDup(vector<int>& nums) {

vector<vector<int>> res;

vector<int> currSet;

sort(nums.begin(),nums.end());

helper(nums,0,res,currSet);

return res;

}