Cod sursa(job #1241394)

Utilizator mihai_brodschiMihai Brodschi mihai_brodschi Data 13 octombrie 2014 14:53:19
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.32 kb
Raporteaza aceasta sursa 
#include <cstdio>

bool a[2000000000];

int main()
{
	freopen ("ciur.in","r",stdin);
	freopen ("ciur.out","w",stdout);
	int n, x=0;
	scanf("%d",&n);
	for (int i=0; i<=n-2; i++)
		if (!a[i])
			for (int j=2; j<=n/(i+2); j++)
				a[(i+2)*j-2]=1;
	for (int i=0; i<=n-2; i++)
		if(!a[i])
			x++;
	printf("%d",x);
    return 0;
}