vector<vector<int>> threeSum(vector<int>& nums) {
    vector<vector<int>> result;
    if(nums.size()==0) return result;
    sort(nums.begin(), nums.end());
    for(int i = 0; i<nums.size(); ){
        int left = i+1;
        int right = nums.size() - 1;
        int target = -nums[i];
        while(left < right){
            if(nums[left] + nums[right] < target) {
                left += 1;
            } else if(nums[left]+nums[right] > target) {
                right -= 1;
            } else {
                result.push_back({nums[i], nums[left], nums[right]});
                left += 1;
                right -= 1;

                while(nums[left]==nums[left-1]) {
                    left += 1;
                }

                while(nums[right]==nums[right+1]) {
                    right -= 1;
                }
            }
        }

        i += 1;
        while(nums[i]==nums[i-1]) {
            i += 1;
        }
    }

    return result;
}