Cod sursa(job #428433)

Utilizator darkseekerBoaca Cosmin darkseeker Data 29 martie 2010 11:39:54
Problema Ciurul lui Eratosthenes Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 0.35 kb
Raporteaza aceasta sursa 

#include <iostream>
#include <fstream>
#include <cmath>
using namespace std;
int main()
{
	fstream f("ciur.in",ios::in);
	fstream g("ciur.out",ios::out);
	int x,i,prim=0,j;
	char v[2000001];
	cin>>x;
	for(i=2;i<=x/2;i++)
		if(!v[i])
		{
			for(j=i*2;j<=x;j+=i)
				v[j]=1;
		}
	for(i=2;i<=x;i++)
		if(!v[i])
			prim++;
	cout<<prim;
}