Cod sursa(job #374650)
Utilizator | Data | 17 decembrie 2009 17:31:17 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 50 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include <stdio.h>
unsigned char v[125001];
int main()
{
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
int n,i,j,counter;
counter=0;
scanf("%d",&n);
for(i=2;i<=n;i++){
if((v[i/8]&(1<<(i%8)))==0){
for(j=i+i;j<=n;j+=i){
v[j/8]=(v[j/8]|(1<<(j%8)));
}
}
}
for(i=2;i<n;i++){
if((v[i/8]&(1<<(i%8)))==0){
counter=counter+1;
}
}
printf("%d",counter);
return 0;
}