Submission #1864026

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

int main(void) {
  int n;
  cin >> n;

  map<int, int> mp;
  for (int i = 0; i < n; i++) {
    int a;
    cin >> a;
    mp[a]++;
  }

  if (mp[3] >= mp[1]) {
    mp[4] += mp[1];
    mp[3] -= mp[1];
    mp[1] = 0;
  } else {
    mp[4] += mp[3];
    mp[1] -= mp[3];
    mp[3] = 0;
  }

  mp[2] += mp[1] / 2;
  mp[1] %= 2;
  mp[4] += mp[2] / 2;
  mp[2] %= 2;
  cout << mp[4] + mp[3] + (mp[1] > 0 || mp[2] > 0) << endl;

  return 0;
}

Submission Info

Judge Result