Its a step to make quickselect
I already have swap written but i dont know how to write this

int partition(int f, int l) {
  int pivot = v[l];
  int i = f;

  for (int j = f; j < l; j++) 
    if (v[j] < pivot) 
      swap(i++,j);

  swap(i, l );
  return (i);
}

Thanks in advance!

chat gpt doesnt work ive tried