Cod sursa(job #374653)
Utilizator | Data | 17 decembrie 2009 17:33:25 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 90 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.39 kb |
#include <stdio.h>
int main()
{
int n,i,v[250010],j,m=0;
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d",&n);
v[0]|=1;
v[0]|=(1<<1);
for(i=1;i<=n;i++){
if((v[i/8]&(1<<(i%8)))==0){
for(j=i+i;j<=n;j+=i){
v[j/8]|=(1<<(j%8));
}
}
}
for(i=1;i<=n;i++){
if((v[i/8]&(1<<(i%8)))==0){
m=m+1;
}
}
printf("%d",m);
return 0;
}