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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int reverse_number(int x) {
  5.     int res = 0;
  6.     while(x > 0) res = res * 10 + (x % 10), x /= 10;
  7.     return res;
  8. }
  9.  
  10. bool is_prime(int x) {
  11.     for(int i=2;i<=sqrt(x);i++) if(x % i == 0) {
  12.         return false;
  13.     }
  14.  
  15.     if(x == 1) return false;
  16.     return true;
  17. }
  18.  
  19. int32_t main() {
  20.     int L, R; cin >> L >> R;
  21.     int reverse_primes = 0;
  22.  
  23.     for(int i = L; i <= R; i++) {
  24.         int num_after_reverse = reverse_number(i);
  25.  
  26.         if(is_prime(num_after_reverse)) {
  27.             reverse_primes++;
  28.         }
  29.     }
  30.  
  31.     cout << reverse_primes;
  32.     return 0;
  33. }
Success #stdin #stdout 0s 5320KB
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https://ideone.com/DonzsM
language:
C++14 (gcc 8.3)
created:
23 hours ago
visibility:
public

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