Cod sursa(job #533764)

Utilizator SadmannCornigeanu Calin Sadmann Data 14 februarie 2011 16:44:37
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.3 kb
Raporteaza aceasta sursa 
#include<stdio.h>
FILE *in=fopen("ciur.in","rt");
FILE *out=fopen("ciur.out","wt");
bool prim[20000001];
int i,j,n,cont;
int main()
{
	fscanf(in,"%d",&n);
	cont=1;
	for(i=3;i<=n;i+=2)
	{
		if(!prim[i])
		{
			for(j=i<<1;j<=n;j+=i)
				prim[j]=true;
			cont++;
		}
	}
	fprintf(out,"%d",cont);
}