Cod sursa(job #489150)

Utilizator crazzytudTudor Popa crazzytud Data 1 octombrie 2010 15:29:12
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.33 kb
Raporteaza aceasta sursa 
#include<stdio.h>
bool c[2000001];
int main()
{
	freopen("ciur.in","r",stdin);
	freopen("ciur.out","w",stdout);
	long n,i,j,num=0;
	scanf("%ld",&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])
			num++;
	printf("%ld",num);
	return 0;
}