Cod sursa(job #2148517)
Utilizator | Iustinian Petrariu IustinPetrariu | Data | 1 martie 2018 19:30:25 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include <iostream>
#include <fstream>
#define nmax 2000005
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int n,prim[nmax],nr=0;
int main()
{
fin>>n;
for(int i =2 ; i <= n ; i++)
prim[i]=1;
for(int i =2 ; i <= n ; i++)
if(prim[i])
{
++nr;
for(int j=i+i; j <= n ; j+=i)
prim[j]=0;
}
fout<<nr;
return 0;
}