Cod sursa(job #588669)
Utilizator | Data | 9 mai 2011 07:50:52 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.41 kb |
#include<cstdio>
using namespace std;
int c[2000005];
void ciur(int n){
int i, j;
for(i = 3; i <= n; i += 2)
if(c[i] == 0) {
for(j = i * i; j <= n; j += i)
c[j] = 1;
}
}
int main() {
int i, j, n;
int nr = 0;
freopen("ciur.in", "r", stdin);
freopen("ciur.out", "w", stdout);
scanf("%d", &n);
ciur(n);
for(i = 3; i <= n; i += 2)
if(c[i] == 0)
++nr;
printf("%d", ++nr);
return 0;
}