Cod sursa(job #368907)
Utilizator | Data | 26 noiembrie 2009 14:50:10 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.4 kb |
#include<iostream>
using namespace std;
int main()
{freopen ("ciur.in", "r", stdin);
freopen ("ciur.out", "w", stdout);
int n,i,v[2000000],j,s;
scanf ("%d", &n);
for(i=2;i<=n;i++){
v[i]=i;
}
v[1]=-1;
for(i=2;i<=n;i++){
if(v[i]>0){
for(j=i+i;j<=n;j+=i){
if(v[j]>0){
v[j]=-v[j];
}
}
}
}
for(i=1;i<=n;i++){
if(v[i]>0){
s++;
}
}
printf("%d", s);
return 0;
}