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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. using namespace std;
  5.  
  6. void sieve(int n)
  7. {
  8.   int i, j;
  9.   vector<bool> is_prime(n+1);
  10.  
  11.   // initialize the list of primes to include all
  12.   // numbers from 2 to n
  13.  
  14.   is_prime[0] = false;
  15.   is_prime[1] = false;
  16.   for (i=2; i<=n; i++)
  17.     is_prime[i] = true;
  18.  
  19.   // do the scratching out
  20.  
  21.   for (i=2; i<=n; i++)
  22.     if (is_prime[i])
  23.       for (j=2*i; j<=n; j+=i)
  24.         is_prime[j] = false;
  25.  
  26.   // print out the primes
  27.  
  28.   for (i=0; i<=n; i++)
  29.     if (is_prime[i])
  30.       cout << i << endl; 
  31. }
  32.  
  33. int main()
  34. {
  35.   int n;
  36.  
  37.   // read n from input
  38.  
  39.   cin >> n;
  40.  
  41.   // find all primes <= n and print them out
  42.  
  43.   sieve(n);
  44.  
  45.   // return from main with 0
  46.  
  47.   return 0;
  48. }
Success #stdin #stdout 0.02s 2816KB
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https://ideone.com/7Zxao
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
secret

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