threesum.cpp

class Solution {
    public:
        vector<vector<int>> threeSum(vector<int>& nums) {
            vector<vector<int>>res;
            int n = nums.size();
            sort(nums.begin(),nums.end());
            for(int i=0;i<n-2;i++){
                if(i>0 && nums[i]==nums[i-1])
                {
                    continue;
                }
                int j=i+1;
                int k=n-1;
                while(j<k){
                    int sum = nums[i] + nums[j] + nums[k];
                    if(sum < 0){
                        j++;
                    }
                    else if(sum > 0){
                        k--;
                    }
                    else{
                        vector<int>temp = {nums[i], nums[j], nums[k]};
                        res.push_back(temp);
                        j++;
                        k--;
                        while(j < k && nums[j] == nums[j-1]){
                            j++;
                        }
                        while(j < k && nums[k] == nums[k+1]){
                            k--;
                        }
                    }
                }
            }
            return res;
        }
    };