std::vector<std::vector<int>> threeSum(std::vector<int>& nums) {

std::vector<std::vector<int>> result;

std::sort(nums.begin(), nums.end());

for(size_t i {0}; i < nums.size(); i++)

{

int front = i + 1;

int back = nums.size() - 1;

while(i+1 < nums.size() && nums[i+1] == nums[i])

i++;

while(front < back)

{

int sum = nums[i] + nums[front] + nums[back];

if(sum < 0)

front ++;

else if(sum > 0)

back --;

else

{

result.push_back({nums[i], nums[front], nums[back]});

while(front<back && nums[front] == nums[front + 1]) front++;

while(front<back && nums[back] == nums[back - 1]) back--;

front ++; back --;

}

}

}

return result;

}

std::vector<int> vec {-1,0,1,2,-1,-4};

for(auto s: Solution{}.threeSum(vec))

{

for(auto c : s)

std::cout<<c<<" ";

std::endl(std::cout);

}

}