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  1. #pragma GCC optimize("O3")
  2. #include <bits/stdc++.h>
  3. using namespace std;
  4. #define ll long long
  5. const int MAXN = 1e6;
  6. bool isPrime[MAXN + 1];
  7. void sieve() {
  8.     fill(isPrime, isPrime + MAXN + 1, true);
  9.     isPrime[0] = isPrime[1] = false;
  10.     for (int i = 2; i * i <= MAXN; i++) {
  11.         if (isPrime[i]) {
  12.             for (int j = i * i; j <= MAXN; j += i)
  13.                 isPrime[j] = false;
  14.         }
  15.     }
  16. }
  17. int digit_sum(int n) {
  18.     int s = 0;
  19.     while (n) {
  20.         s += n % 10;
  21.         n /= 10;
  22.     }
  23.     return s;
  24. }
  25. int reverse_num(int n) {
  26.     int r = 0;
  27.     while (n) {
  28.         r = r * 10 + n % 10;
  29.         n /= 10;
  30.     }
  31.     return r;
  32. }
  33. int main() {
  34.     ios::sync_with_stdio(false);
  35.     cin.tie(nullptr);
  36.     freopen("BEST.inp", "r", stdin);
  37.     freopen("BEST.out", "w", stdout);
  38.     sieve();
  39.     int Q;
  40.     cin >> Q;
  41.     while (Q--) {
  42.         int n;
  43.         cin >> n;
  44.         if (!isPrime[n]) {
  45.             cout << "No\n";
  46.             continue;
  47.         }
  48.         if (digit_sum(n) % 2 != 0) {
  49.             cout << "No\n";
  50.             continue;
  51.         }
  52.         int rev = reverse_num(n);
  53.         if (rev <= MAXN && isPrime[rev]) cout << "Yes\n";
  54.         else cout << "No\n";
  55.     }
  56. }
  57.  
Time limit exceeded #stdin #stdout 5s 5332KB
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https://ideone.com/vuQm3k
language:
C++14 (gcc 8.3)
created:
54 days ago
visibility:
public

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