July_8.cpp

class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
        int n = nums.size();
        if(n < 3) 
            return {};
        vector<vector<int>> v;
        sort(nums.begin(), nums.end());
        for(int i = 0; i < n-2; i++)
        {
            if(i == 0 || nums[i] != nums[i-1])
            {
                
                int j = i+1, k = n-1;
                while(j < k)
                {
                    int sum = nums[i] + nums[j] + nums[k];
                    if(sum == 0) 
                    {
                        v.push_back({nums[i], nums[j], nums[k]});
                        
                        while(j < k && nums[j] == nums[j+1]) 
                            j++;
                        
                        while(j < k && nums[k] == nums[k-1]) 
                            k--;
                        
                        j++; 
                        k--;
                    }
                    else if (sum < 0) 
                        j++;
                    else 
                        k--;
                }
            }
        }
        return v;
    }
};