Cod sursa(job #191758)
Utilizator | Silvia Pripoae silvia_the_best | Data | 28 mai 2008 11:10:52 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.52 kb |
#include <stdio.h>
int n,nr;
bool v[2000000];
void ciur(){
int i,m;
v[0]=1;
v[1]=1;
for (m=4;m<=n;m+=2)
v[m]=1;
for (i=3;i<=n;i+=2){
if (v[i]==0){
m=0;
for (m=i+i;m<=n;m+=i)
v[m]=1;
}
}
for (i=1;i<=n;++i)
if (v[i]==0)
++nr;
return;
}
int main()
{
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d",&n);
ciur();
printf("%d",nr);
return 0;
}