3 sum problem

class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) 
    {
        vector<vector<int>> ans;
        int n = nums.size();
        sort(nums.begin(), nums.end());
        for(int i=0; i<n-2; i++)
        {
            int left = i+1, right = n-1;
            while(left < right)
            {
                int s = nums[i] + nums[left] + nums[right];
                if(s < 0) left++;
                else if(s > 0) right--;
                else
                {
                    vector<int> t(3);
                    t[0] = nums[i];
                    t[1] = nums[left];
                    t[2] = nums[right];
                    ans.push_back(t);
                    left++;
                    right--;
                    while(left < right && nums[left] == t[1]) left++;
                     while(left < right && nums[right] == t[1]) right--;
                }
            }
            while(i < n-2 && nums[i] == nums[i+1]) i++;
        }
        return ans;
    }
};