Cod sursa(job #1925592)
Utilizator | Coman Mara Stefania Mstar_Angel | Data | 13 martie 2017 14:06:14 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.51 kb |
#include<stdio.h>
#define N 2000002
bool ciur[N];
int n;
void ciur_eratostene (){
int d,i;
for (d=2;d<n;d++)
if (ciur[d] == 0){
for (i=d*d;i<=n;i+=d)
ciur[i] = 1;
}
}
int main (){
FILE *in,*out;
in = fopen ("ciur.in","r");
out = fopen ("ciur.out","w");
int i,cate;
fscanf(in,"%d",&n);
ciur_eratostene ();
cate = 0;
for (i=2;i<=n;i++)
if (ciur[i] == 0)
cate ++;
fprintf (out,"%d",cate);
fclose (in);
fclose (out);
return 0;
}