Before reading this problem please note that this is a PRACTICE problem for hp codewars (a programming competition), I am not asking the forum about a real problem. My program is supposed to take the following input:

-a number that represent the number of candies in a jar

-the number of guesses that the user will be entering in

-a person's name, followed by a space and then their guess

ex:

422 ----------------- amount of candies in jar

2 -------------------- number of guesses

joe 324 -------------name of guesser and their guess of how many candies are in the jar

mary 435 ----------second guesser and guess

The output should be the name of the person who had the closest guess

ex:

mary

I am currently coding the function that returns the closest number to the guess. However when I run the code, it gives me the error "no match for call '(std::vector) (int)" on two lines. The lines that are sending back errors are pointed out in comments in my code.

Here is my code:

vector<int> compare(vector<int> nums, int loopnum, int ans)
{
   vector<int> buff2;
  for (int i = 0; i<loopnum;i++)
  {
      vector<int>diff;
      int buff = ans - nums.at(i);
      for (int j = 0; j<loopnum; j++)
      {
         diff.push_back(buff);
         for (int k = 0; k<diff.size(); k++)
         {
             if (k == 0)
             {
                buff2.push_back(diff.at(k));
             }
             else
             {
                 if ((abs(buff2(0))) > abs(diff.at(k))) // this line is sending back an error
                 {
                     buff2.clear();
                     buff2.push_back(diff.at(k));
                 }
                 else if ((abs(buff2(0))) == abs(diff.at(k))) // this line is also sending back an error
                 {
                     buff2.push_back(diff.at(k));
                 }
             }
         }
      }

  }
  return buff2;
}

Please help me fix this!