C. Removal of Unattractive Pairs.cpp

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

#define mod 998244353

bool check(int k, vector<vector<int>> &seg)
{
  int ll = 0, rr = 0;
  for (auto &e : seg)
  {
    ll = max(ll - k, e[0]);
    rr = min(rr + k, e[1]);
    if (ll > rr)
      return false;
  }

  return true;
}

int solve(vector<vector<int>> &seg)
{
  int l = -1, r = 1e9;
  while (r - l > 1)
  {
    int mid = (r + l) / 2;
    if (check(mid, seg))
    {
      r = mid;
    }
    else
    {
      l = mid;
    }
  }
  return r;
}

int main()
{

  int t;
  cin >> t;
  while (t--)
  {

    int n;
    cin >> n;
    vector<int> cnt(26, 0);
    string s;
    cin >> s;
    for (char c : s)
    
      cnt[c - 'a']++;
    
    int mx = *max_element(cnt.begin(), cnt.end());
    cout << max(n % 2, 2 * mx - n) << endl;

    
  }
}