Cod sursa(job #1810714)
Utilizator | Data | 20 noiembrie 2016 14:45:07 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.48 kb |
#include <iostream>
#include <cstdio>
using namespace std;
int n,k;
bool neprim[2000001];
void ciur()
{
for(int i=2;i*i<=n;i++)
{
if(!neprim[i])
{
for(int j=2*i;j<=n;j+=i)
neprim[j]=1;
}
}
for(int i=2;i<=n;i++)
if(!neprim[i]) ++k;
}
int main()
{
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d",&n);
ciur();
printf("%d",k);
return 0;
}