Cod sursa(job #757860)
Utilizator | Data | 13 iunie 2012 17:31:14 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.4 kb |
#include<stdio.h>
char a[2000001];
int ciuruire(int n)
{
int i,j;
int s=0;
for(i=2;i<=1420&&(i<=n);++i)
if(a[i] == 0)
{
s++;
for(j=i*i;j<=n;j += i)
{
a[j] = i;
}
}
for(;i<=n;i++)
if(a[i] == 0)
s++;
return s;
}
int main()
{
int n;
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d",&n);
printf("%ld",ciuruire(n));
return 0;
}