Nc54 sum of three numbers

class Solution {
    
public:
    vector<vector<int> > threeSum(vector<int> &num) {
    
        vector<vector<int>>ans;
        sort(num.begin(),num.end());
        for(int i=0;i<num.size();i++){
    
            if(num[i]>0) break;
            if(i>0&&num[i]==num[i-1]) continue;
            int target=0-num[i];
            int l=i+1,r=num.size()-1;
            while(l<r){
    
                
                if(num[l]+num[r]==target){
    
                    while(num[l]==num[l+1]&&l<r) l++;
                    while(num[r]==num[r-1]&&l<r) r--;
                    ans.push_back({
    num[i],num[l],num[r]});
                    l++;
                    r--;  
                }
                else if(num[l]+num[r]<target) l++;
                else r--;
            }
        }
        return ans;
    }
};