Cod sursa(job #729677)
Utilizator | Data | 29 martie 2012 19:54:49 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.45 kb |
#include <cstdio>
#define Maxn 2000001
using namespace std;
FILE *f1, *f2;
int n,prime,i,j;
bool nr[Maxn];
int main()
{
f1 = freopen("ciur.in", "r", stdin);
scanf("%i", &n);
fclose(f1);
nr[0]=nr[1]=0;
for(i=2;i<=n;i++) nr[i] = true;
for(i=2;i<=n;i++)
{
if(nr[i])
{
prime ++;
for(j=i+i;j<=n;j+=i) nr[j] = false;
}
}
f2 = freopen("ciur.out", "w", stdout);
printf("%i\n", prime);
fclose(f2);
return 0;
}