Cod sursa(job #729664)
Utilizator | Data | 29 martie 2012 19:48:56 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.44 kb |
#include <cstdio>
#define Maxn 2000001
using namespace std;
FILE *f1, *f2;
long int n,prime,i,j;
short int nr[Maxn];
int main()
{
f1 = freopen("ciur.in", "r", stdin);
scanf("%li", &n);
fclose(f1);
nr[0]=nr[1]=0;
for(i=2;i<=n;i++) nr[i] = 1;
for(i=2;i<=n;i++)
{
for(j=i+i;j<=n;j+=i) nr[j] = 0;
}
for(i=2;i<=n;i++) prime+=nr[i];
f2 = freopen("ciur.out", "w", stdout);
printf("%li\n", prime);
fclose(f2);
return 0;
}