Cod sursa(job #527753)

Utilizator ioanabIoana Bica ioanab Data 1 februarie 2011 10:24:25
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.36 kb
Raporteaza aceasta sursa 
#include <cstdio>
using namespace std;

const int N=2000005;
bool c[N];


int main()
{
	freopen("ciur.in","r",stdin);
	freopen("ciur.out","w",stdout);
	int n,i,j,nr;
	scanf("%d",&n);
	nr=0;
	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])
			nr++;
	
	printf("%d\n",nr);
	return 0;
}