Cod sursa(job #660883)

Utilizator roxana_savulescuSavulescu Roxana roxana_savulescu Data 13 ianuarie 2012 14:13:25
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.32 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
long n,i,nr,j;
bool a[2000001];
int main(){
	ifstream f("ciur.in");
	ofstream g("ciur.out");
	f>>n;
	for (i=2;i<=n/2;i++){
		if (a[i]==false){
			nr++;
			for (j=2;j<=n/i;j++)
				a[i*j]=true;
		}
	}
	for (i=n/2+1;i<=n;i++)
		if (a[i]==false) nr++;
	g<<nr;
	return 0;
}