Cod sursa(job #1007403)
Utilizator | Data | 8 octombrie 2013 21:26:46 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.44 kb |
#include <iostream>
#include <fstream>
#include <string.h>
using namespace std;
int a[2000001],n,nr;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
void marcare(int x)
{
for(int i=x+x;i<=n;i+=x)
a[i]=1;
}
void ciur()
{
for(int i=2;i<=n;i++)
if(!a[i])
{
nr++;
marcare(i);
}
}
int main()
{
fin>>n;
ciur();
fout<<nr;
return 0;
}