Game with String.cpp

/*
Game with String
=================

Given a string s of lowercase alphabets and a number k, the task is to print the minimum value of the string after removal of ‘k’ characters. The value of a string is defined as the sum of squares of the count of each distinct character.

Example 1:
Input: s = abccc, k = 1
Output: 6
Explaination:
We remove c to get the value as 12 + 12 + 22

Example 2:
Input: s = aabcbcbcabcc, k = 3
Output: 27
Explaination: We remove two 'c' and one 'b'. 
Now we get the value as 32 + 32 + 32.

Your Task:
You do not need to read input or print anything. Your task is to complete the function minValue() which takes s and k as input parameters and returns the minimum possible required value.

Expected Time Complexity: O(N*logN)  where N is the length of string
Expected Auxiliary Space: O(N)

Constraints:
1 ≤ k ≤ |string length| ≤ 100
*/

int minValue(string s, int k)
{
  vector<int> freq(26, 0);
  for (auto &i : s)
    freq[i - 'a']++;

  priority_queue<int> pq;
  for (auto &i : freq)
    pq.push(i);

  for (int i = 0; i < k; ++i)
  {
    auto tp = pq.top();
    pq.pop();
    tp--;
    pq.push(tp);
  }

  int ans = 0;
  while (pq.size())
  {
    auto tp = pq.top();
    pq.pop();
    ans += (tp * tp);
  }

  return ans;
}