Cod sursa(job #531234)

Utilizator belicosuspusherino TALENT belicosus Data 9 februarie 2011 11:19:55
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.28 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");

bool c[2000005];

int main()
{
	int n,i,j,p=0;
	in>>n;
	for(i=2;i*i<=n;i++)
		if(!c[i])
			for(j=i*i;j<=n;j+=i)
				c[j]=true;
	for(i=2;i<=n;i++)
		if(!c[i])
			p++;
	out<<p;
}