Find Four Elements That Sums To A Given Value : Wrong Output

Question

I am trying to solve the question,

Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:

0 <= a, b, c, d < n
a, b, c, and d are distinct.
nums[a] + nums[b] + nums[c] + nums[d] == target

You may return the answer in any order.

I think I have understood the logic that I need to implement, but my code it is not giving the desired output.

Example: Input: [-3,-2,-1,0,0,1,2,3], 0

The expected output is:

[
  [-3,-2,2,3],
  [-3,-1,1,3],
  [-3,0,0,3],
  [-3,0,1,2],
  [-2,-1,0,3],
  [-2,-1,1,2],
  [-2,0,0,2],
  [-1,0,0,1]
]

but my code outputs this:

[
  [-3,-2,2,3],
  [-3,-1,1,3],
  [-3,0,0,3],
  [-2,-1,0,3],
  [-2,0,0,2],
  [-1,0,0,1]
]

My C++ Code below:

class Solution {

public:
    vector<vector<int>> fourSum(vector<int>& nums, int target) {
        int n=nums.size();
        vector<vector<int>> ans;
        int low;
        int high;
        sort(nums.begin(),nums.end());
        for(int i=0;i<n-2;i++)
        {
            for(int j=i+1;j<n-1;j++)
            {
                low=j+1;
                high=n-1;
                int req=target-(nums[i]+nums[j]);
                while(low<high)
                {
                    if(nums[low]+nums[high]==req)
                    {
                 ans.push_back({nums[i],nums[j],nums[low],nums[high]});
                     while(high>low && nums[high-1]==nums[high])
                         --high;
                     while(high>low && nums[low+1]==nums[low])
                         ++low;
                        break;
                    }
                    else if(nums[low]+nums[high]>req)
                    {
                        high--;
                    }
                    else
                        low++;
                }
                while(j+1<n && nums[j]==nums[j+1])
                    ++j;
                while(i+1<n && nums[i]==nums[i+1])
                    ++i;
            }
        }
        return ans;
    }
};

Where is the mistake?