LeetCode 15 3Sum

class Solution {
public:
    map<pair<int,int>,int> m;
    vector<vector<int>> threeSum(vector<int>& nums) {
        
        vector<vector<int>> ans;
        vector<int> res;
        sort(nums.begin(),nums.end());
        
        for(int i=0;i<nums.size();i++)
        {
            if(i!=0&&nums[i]==nums[i-1])
                continue;
            int start=i+1;
            int end=nums.size()-1;
            int x=-1*nums[i];
            while(start<end)
            {
                if(nums[end]+nums[start]>x)
                {
                    end--;
                    continue;
                }
                else if(nums[end]+nums[start]<x)
                {
                    start++;
                    continue;
                }
                else
                {
                   
                    res.clear();
                    res.push_back(nums[end]);
                    res.push_back(nums[start]);
                    res.push_back(nums[i]);
                    ans.push_back(res);  
                    
                     while(start<end&&nums[end]==nums[end-1])
                        end--;
                    while(start<end&&nums[start]==nums[start+1])
                        start++;
                    
                    start++;
                    end--;
                    
                   
                  
                }
            }
        }
        
        return ans;
        
    }
};