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  1. #include <stdio.h>
  2. #include <math.h>
  3. #include <vector>
  4. #include <time.h>
  5.  
  6. using namespace std;
  7.  
  8. int N,cnt = 0;
  9. vector<int> primes;
  10.  
  11. int is_prime(int p)
  12. {
  13.     int sq = sqrt(p);
  14.     for (int ps : primes) {
  15.         if(sq < ps)
  16.             return 1;
  17.         if(p % ps == 0)
  18.             return 0;
  19.     }
  20.     return 1;
  21. }
  22.  
  23. void prime(int N)
  24. {
  25.     int k = 0;
  26.     cnt += 2;
  27.     primes.push_back(2);
  28.     primes.push_back(3);
  29.     while (cnt < N) {
  30.         k++;
  31.         if(is_prime(6*k-1) == 1){
  32.             cnt ++;
  33.             primes.push_back(6*k-1);
  34.         }
  35.         if(is_prime(6*k+1) == 1){
  36.             cnt ++;
  37.             primes.push_back(6*k+1);
  38.         }
  39.     }
  40.     return;
  41. }
  42.  
  43. int main() {
  44.     int a;
  45.     clock_t start,end;
  46.     double result;
  47.     scanf("%d",&a);
  48.     scanf("%d", &N);
  49.     start = clock();
  50.     prime(N);
  51.     if(a == 1) printf("%d",primes[N-1]);
  52.     if(a == 0) for(int x : primes)
  53.         printf("%d ",x);
  54.     end = clock();
  55.     result = (double)(end - start);
  56.     printf("%f",result);
  57.     return 0;
  58. }
Success #stdin #stdout 2.97s 12460KB
comments (?)
stdin 
1 1500000
stdout 
238795192963485.000000
https://ideone.com/CP3yon
language:
C++14 (gcc 8.3)
created:
15 days ago
visibility:
public

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