Find All Four Sum Numbers

vector<vector<int> > fourSum(vector<int> &arr, int k) {
        // Your code goes here
        sort(arr.begin(),arr.end());

        vector<vector<int>>ans;
        for(int i=0 ; i<arr.size() ; i++)
        {
            if(i>0 && arr[i]==arr[i-1])
            {
                continue;
            }
            for(int j=arr.size()-1 ; j>=i+3 ; j--)
            {
                if(j<arr.size()-1 && arr[j]==arr[j+1])
                {
                    continue;
                }
                int low =i+1;
                int high=j-1;
                while(low<high)
                {

                    int sum=arr[i]+arr[j]+arr[low]+arr[high];
                    if(sum==k)
                    {
                        ans.push_back({arr[i],arr[low],arr[high],arr[j]});
                        while(arr[low]==arr[low+1])
                        {
                            low++;
                        }
                        low++;
                        while(arr[high]==arr[high-1])
                        {
                            high--;
                        }
                        high--;
                    }
                    else if(sum<k)
                    {
                        while(arr[low]==arr[low+1])
                        {
                            low++;
                        }
                        low++;
                    }
                    else{
                        while(arr[high]==arr[high-1])
                        {
                            high--;
                        }
                        high--;
                    }
                }
            }
        }
        sort(ans.begin(),ans.end());
        return ans;
   }
// https://practice.geeksforgeeks.org/problems/find-all-four-sum-numbers1732/