Cod sursa(job #306632)
Utilizator | Data | 21 aprilie 2009 18:15:32 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.37 kb |
#include<fstream.h>
int main()
{
int n,i,j,k=0;
char c[1000]={0};
ifstream in("ciur.in");
ofstream out("ciur.out");
in>>n;
for (i=1;i<=n;i++)
c[i]=i;
for (i=3;i<=n;i++)
if (i%2==0) c[i]=0;
for (i=1;i*i<=n;i++)
if (c[i]==0)
for (j=i*i;i<=n;j+=i)
c[j]=1;
for (i=2;i<=n;i++)
if (c[i]==0) k++;
out<<k;
in.close();
out.close();
return 0;
}