Cod sursa(job #356055)

Utilizator matzipanAndrei matzipan Data 13 octombrie 2009 12:57:42
Problema Ciurul lui Eratosthenes Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 0.33 kb
Raporteaza aceasta sursa 
#include <fstream>

using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");
unsigned long N,i,v[2000000]; 

long era() {
	long x,nr,i;
	nr=N;
	for(i=2; i<=N; i++)	if(v[i]!=0) for(x=i; x*i<N; x++) 
		{ nr--; v[i]=0; }
	return nr;
}
int main() {
	in>>N;
	for(i=2; i<=N; i++) v[i]=1;
	out<<era();
	return 0;
}