Problem p03976 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
// #include <utility>
// #include <memory>
// #include <functional>
// #include <deque>
// #include <cctype>
// #include <ctime>
// #include <numeric>
// #include <list>
// #include <iomanip>

// #if __cplusplus >= 201103L
// #include <array>
// #include <tuple>
// #include <initializer_list>
// #include <forward_list>
//
// #define cauto const auto&
// #else

// #endif

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

typedef vector<int> vint;
typedef vector<vector<int>> vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long>> vvll, vvLL;

#define VV(T) vector<vector<T>>

template <class T>
void initvv(vector<vector<T>> &v, int a, int b, const T &t = T()) {
  v.assign(a, vector<T>(b, t));
}

template <class F, class T> void convert(const F &f, T &t) {
  stringstream ss;
  ss << f;
  ss >> t;
}

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define reep(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) reep((i), 0, (n))
#define ALL(v) (v).begin(), (v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(), (v).rend()
#define DEBUG
#ifdef DEBUG
#define dump(x) cout << #x << " = " << (x) << endl;
#define debug(x)                                                               \
  cout << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \
       << " " << __FILE__ << endl;
#else
#define dump(x)
#define debug(x)
#endif

#define MOD 1000000007LL
#define EPS 1e-8
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define maxs(x, y) x = max(x, y)
#define mins(x, y) x = min(x, y)

void mainmain() {
  int n, K;
  cin >> n >> K;
  vint cnt(26);
  rep(i, n) {
    string s;
    cin >> s;
    cnt[s[0] - 'A']++;
  }
  sort(ALL(cnt));
  reverse(ALL(cnt));
  ll m = INF;
  while (1) {
    int t = 0;
    rep(i, 26) { t += min(m, (ll)cnt[i]); }
    if (m * K <= t) {
      cout << m << endl;
      return;
    }
    m--;
  }
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(20);
  mainmain();
}

Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
// #include <utility>
// #include <memory>
// #include <functional>
// #include <deque>
// #include <cctype>
// #include <ctime>
// #include <numeric>
// #include <list>
// #include <iomanip>

// #if __cplusplus >= 201103L
// #include <array>
// #include <tuple>
// #include <initializer_list>
// #include <forward_list>
//
// #define cauto const auto&
// #else

// #endif

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

typedef vector<int> vint;
typedef vector<vector<int>> vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long>> vvll, vvLL;

#define VV(T) vector<vector<T>>

template <class T>
void initvv(vector<vector<T>> &v, int a, int b, const T &t = T()) {
  v.assign(a, vector<T>(b, t));
}

template <class F, class T> void convert(const F &f, T &t) {
  stringstream ss;
  ss << f;
  ss >> t;
}

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define reep(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) reep((i), 0, (n))
#define ALL(v) (v).begin(), (v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(), (v).rend()
#define DEBUG
#ifdef DEBUG
#define dump(x) cout << #x << " = " << (x) << endl;
#define debug(x)                                                               \
  cout << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \
       << " " << __FILE__ << endl;
#else
#define dump(x)
#define debug(x)
#endif

#define MOD 1000000007LL
#define EPS 1e-8
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define maxs(x, y) x = max(x, y)
#define mins(x, y) x = min(x, y)

void mainmain() {
  int n, K;
  cin >> n >> K;
  vint cnt(26);
  rep(i, n) {
    string s;
    cin >> s;
    cnt[s[0] - 'A']++;
  }
  sort(ALL(cnt));
  reverse(ALL(cnt));
  ll m = INF / 100;
  while (1) {
    int t = 0;
    rep(i, 26) { t += min(m, (ll)cnt[i]); }
    if (m * K <= t) {
      cout << m << endl;
      return;
    }
    m--;
  }
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(20);
  mainmain();
}