Cod sursa(job #1256338)
Utilizator | Lazar Vlad Lester | Data | 6 noiembrie 2014 08:50:11 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.49 kb |
#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int n,s;
bool a[2000002];
void ciur()
{
a[0]=a[1]=1;
for(int i=2;i<=n;i++)
{
if(a[i]==0)
{
for(int j=2*i;j<=n;j=j+i)
a[j]=1;
}
}
}
int main()
{
fin>>n;
ciur();
for(int i=2;i<=n;i++)
{
if(a[i]==0)
s++;
}
fout<<s;
// cout << sizeof(a)/1000;
}