Cod sursa(job #223042)

Utilizator Andreid91Ciocan Andrei Andreid91 Data 26 noiembrie 2008 19:17:51
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.34 kb
Raporteaza aceasta sursa 
#include<fstream.h>

int  n,i,j,nr=1;

char v[1000002];

int main()
{
ifstream f ("ciur.in");
f>>n;
f.close();
i=1;
while  ((i*i*2+i*2)<= n)
{
	if ( v[i]==0 )
	{
		for ( j=i*i*2+2*i ; 2*j+1<=n ; j+=2*i+1 )
			v[j]=1;
	}
	i++;
}
for (i=1;2*i+1<=n;i++)
	if (!v[i]) nr++;
ofstream g("ciur.out");
g<<nr;
g.close();
return 0;
}