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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. bool p[(int)1e7+5];
  4.  
  5. void check(int x, int k){
  6.     // cout << "k: " << k << endl;
  7.     for(int i = 2; i <= k; i++){
  8.         if(p[i] == false){
  9.             for(int j = i; j <= x; j += i){
  10.                 p[j] = true;
  11.             }
  12.         }
  13.     }
  14.     // for(int i = 1; i <= x; i++){
  15.     //     cout << i << " " << p[i] << endl;
  16.     // }
  17. }
  18.  
  19.  
  20. int main() {
  21.     int t,a,k;
  22.     cin >> t >> a >> k;
  23.     int x = t/a;
  24.     check(x, k);
  25.     int cnt = 0;
  26.     for(int i = 1; i <= x; i++){
  27.         if(p[i] == false) cnt++;
  28.     }
  29.     cout << cnt << "\n";
  30.     return 0;
  31. }
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/FgMe09
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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