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  1. /*
  2.     Cred : SunnyYeahBoi
  3.     It's my last chance (⌐■_■)
  4.     Problem :
  5. */
  6.  
  7. #include<bits/stdc++.h>
  8.  
  9. using namespace std;
  10.  
  11. #define int long long
  12. #define double long double
  13. #define endl "\n"
  14. #define NAME "a"
  15.  
  16. const int MAXN = 1e6 + 5;
  17. const int inf = 1e18;
  18. const int MOD = 1e9 + 7;
  19.  
  20. void FileInput(){
  21.     if(fopen(NAME".inp" , "r") == NULL)
  22.         freopen(NAME".inp" , "w" , stdout);
  23.     freopen(NAME".inp" , "r" , stdin);
  24.     freopen(NAME".out" , "w" , stdout);
  25. }
  26.  
  27. int n;
  28. int cnt[5];
  29.  
  30. void solve(){
  31.     cin >> n;
  32.     for(int i = 1 ; i <= n ; i++){
  33.         int x;
  34.         cin >> x;
  35.         cnt[x]++;
  36.     }
  37.  
  38.     int res = 0 , t;
  39.     res += cnt[4];
  40.     t = min(cnt[1] , cnt[3]);
  41.     cnt[1] -= t;
  42.     cnt[3] -= t;
  43.     res += t;
  44.     if(cnt[3] > 0) res += cnt[3];
  45.     t = cnt[2] / 2;
  46.     res += t;
  47.     cnt[2] = cnt[2] % 2;
  48.     res += (cnt[1] + cnt[2] * 2 + 3) / 4;
  49.  
  50.     cout << res << endl;
  51. }
  52.  
  53. int32_t main(){
  54.     FileInput();
  55.     ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  56.     int t = 1;
  57.     // cin >> t;
  58.     while(t--)
  59.         solve();
  60.     return 0;
  61. }
  62.  
Success #stdin #stdout 0.01s 5320KB
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https://ideone.com/9nbayM
language:
C++14 (gcc 8.3)
created:
16 days ago
visibility:
public

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