Cod sursa(job #269330)
Utilizator | Data | 2 martie 2009 19:49:53 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.4 kb |
#include <stdio.h>
#define dim 200004
char ciur[dim];
int i, j, k, n;
int main(void)
{
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d", &n);
for ( i = 2; i <= n; i++)
ciur[i] = 1;
for(i = 2; i <= n; i++)
if(ciur[i])
for(j = 2; j <= n/i; j++)
ciur[ i*j ] = 0;
for(i = 2; i <= n; i++)
if(ciur[i])
k++;
printf("%d\n",k);
fcloseall();
return 0;
}