Cod sursa(job #308518)

Utilizator doru.nituNitu Doru Constantin doru.nitu Data 27 aprilie 2009 16:38:40
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.31 kb
Raporteaza aceasta sursa 
#include<stdio.h>
FILE *f=fopen("ciur.in","r"),
     *g=fopen("ciur.out","w");
char a[2000010];
int i,n,nr,k;
int main()
{ fscanf(f,"%d",&n);
  for(i=2;i*i<=n;i++)  if(!a[i]) for(k=i*i;k<=n;k+=i) a[k]=1;

  for(i=2;i<=n;i++) if(!a[i]) nr++;
  fprintf(g,"%d\n",nr);
  fclose(f);
  fclose(g);
  return 0;
}