Cod sursa(job #595680)
Utilizator | Anghel Anca Athena99 | Data | 13 iunie 2011 15:31:14 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include <stdio.h>
#include <math.h>
long long v[2000000];
int main()
{
long long n=0,i=0,p=0,j=0;
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%lld",&n);
for (i=2; i<=n; ++i) v[i]=i;
for (i=2; i<=n; ++i)
if (v[i]!=0 && i>sqrt(n)+1) ++p;
else if (v[i]!=0)
{
for (j=2*i; j<=n; j+=i) v[j]=0;
++p;
}
printf("%lld",p);
return 0;
}