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  1. /* ================================================
  2.  *  _____   _____   _____   _____ 
  3.  * /  ___| |  _  \ |_   _| /  ___|
  4.  * | |     | |_| |   | |   | |___ 
  5.  * | |     |  _  /   | |   \___  \
  6.  * | |___  | | \ \  _| |_   ___| |
  7.  * \_____| |_|  \_\|_____| |_____/
  8.  *
  9.  * "Quality is not an act, it is a habit."
  10.  ==================================================== */
  11. #include "bits/stdc++.h"
  12. #define int long long
  13. #define vi vector <int>
  14. #define vv vector <vector<int>>
  15. #define all(v) v.begin() , v.end()
  16. using namespace std;
  17.  
  18. template<typename T>
  19. istream &operator>>(istream &in, vector<T> &v) {
  20.     for (auto &x: v) in >> x;
  21.     return in;
  22. }
  23.  
  24. template<typename T>
  25. ostream &operator<<(ostream &out, const vector<T> &v) {
  26.     for (size_t i = 0; i < v.size(); ++i) out << v[i] << (i + 1 == v.size() ? "" : " ");
  27.     return out;
  28. }
  29.  
  30. const int N = 20, mod = 1e9 + 7;
  31. int n;
  32. bool used[17] = {false};
  33. vi v = {1};
  34. set <int> primes = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31};
  35.  
  36. void garb(int idx = 2, int cnt = 1){
  37.     if(cnt == n){
  38.         if(!primes.count(v[0] + v[n - 1])) return;
  39.         cout << v << endl;
  40.         return;
  41.     }
  42.     if(idx > n) return;
  43.  
  44.     if(!used[idx] and primes.count(v.back() + idx)){
  45.         used[idx] = true;
  46.         v.push_back(idx);
  47.         garb(2, cnt + 1);
  48.  
  49.         v.pop_back();
  50.         used[idx] = false;
  51.     }
  52.  
  53.     garb(idx + 1, cnt);
  54. }
  55.  
  56. void solve() {
  57.     int c = 1;
  58.     while(cin >> n){
  59.         v.clear();
  60.         v.push_back(1);
  61.         cout << "Case " << c ++ << ":\n";
  62.         garb();
  63.     }
  64. }
  65.  
  66. signed main() {
  67.     ios_base::sync_with_stdio(false);
  68.     cin.tie(NULL);
  69.  
  70.     int t = 1;
  71.     // cin >> t;
  72.     while (t--) {
  73.         solve();
  74.     }
  75.  
  76.     return 0;
  77. }
Success #stdin #stdout 0s 5324KB
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https://ideone.com/u8FYEh
Prime Ring
language:
C++ (gcc 8.3)
created:
4 hours ago
visibility:
public

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