Three Sum.cpp

vector<vector<int>> triplet(int n, vector<int> &arr) {

  vector<vector<int>> ans;

  sort(arr.begin(), arr.end());

 

  for (int i = 0; i < n; i++) {

    if (i > 0 && arr[i] == arr[i - 1])

      continue;

    int j = i + 1;

    int k = n - 1;

    while (j < k) {

      int sum = arr[i] + arr[j] + arr[k];

 

      if (sum < 0) {

        j++;

      } else if (sum > 0) {

        k--;

      } else {

        vector<int> temp = {arr[i], arr[j], arr[k]};

        ans.push_back(temp);

        j++;

        k--;

        while (j < k && arr[j] == arr[j - 1])

          j++;

        while (j < k && arr[k] == arr[k + 1])

          k--;

      }

    }

  }

  return ans;

}