Cod sursa(job #161855)

Utilizator c_e_manuEmanuel Cinca c_e_manu Data 18 martie 2008 21:19:33
Problema Ciurul lui Eratosthenes Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 0.32 kb
Raporteaza aceasta sursa 
#include<fstream.h>

long long ok[2000005];
long i,j,n,k;
int main()
{	ifstream fin("ciur.in");
	ofstream fout("ciur.out");
	fin>>n;
        for(i=2;i*i<=n;i++)
		if(!ok[i])
		{       j=2;
			while(i*j<=n)
			{	ok[i*j]=1;
				j++;
			}
		}
	for(i=2;i<=n;i++)
		if(!ok[i]) k++;
	fout<<k;
        return 0;
}