Cod sursa(job #523589)
Utilizator | Data | 18 ianuarie 2011 16:57:49 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.39 kb |
#include<stdio.h>
int prim[2000001],n,x;
int primes(int n)
{
int i,j;
for(i=2;i<=n;++i) prim[i]=1;
for(i=4;i<=n;i+=2) prim[i]=0;
for(i=3; i*i<=n; i+=2)
if(prim[i])
for(j=i*i;j<=n;j+=i) {prim[j]=0; n--;}
return n;
}
int main()
{
freopen("ciur.in","rt",stdin);
freopen("ciur.out","wt",stdout);
scanf("%d",&n);
//x=primes(n);
printf("%d\n",primes(n));
return 0;
}