fork download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. /*
  5.     lời giải dưới chỉ áp dụng cho sub1 (L, R <= 2e3)
  6.     Không thể giải sub cuối!!! (hoặc có)
  7. */
  8.  
  9. int reverse_number(int x) {
  10.     int res = 0;
  11.     while(x > 0) res = res * 10 + (x % 10), x /= 10;
  12.     return res;
  13. }
  14.  
  15. bool is_prime(int x) {
  16.     for(int i=2;i<=sqrt(x);i++) if(x % i == 0) {
  17.         return false;
  18.     }
  19.  
  20.     if(x == 1) return false;
  21.     return true;
  22. }
  23.  
  24. int32_t main() {
  25.     int L, R; cin >> L >> R;
  26.     int reverse_primes = 0;
  27.  
  28.     for(int i = L; i <= R; i++) {
  29.         int num_after_reverse = reverse_number(i);
  30.  
  31.         if(is_prime(num_after_reverse)) {
  32.             reverse_primes++;
  33.         }
  34.     }
  35.  
  36.     cout << reverse_primes;
  37.     return 0;
  38. }
Success #stdin #stdout 0.01s 5316KB
comments (?)
stdin
copy 
20 35
stdout
copy 
6
https://ideone.com/HoMY1R
language:
C++14 (gcc 8.3)
created:
23 hours ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!