Cod sursa(job #776866)
Utilizator | fmi - pop oana oana_pop | Data | 10 august 2012 16:06:52 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 20 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.44 kb |
#include <fstream>
#include <stdio.h>
#include <math.h>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int main()
{
bool a[10000];
int nr=1 , n , i , j;
fin>>n;
for(i=3; i<=n ; i+=2) a[i]=1;
for(i=3; i<=sqrt(n); i+=2)
if(a[i])
for(j=i ; j<=n/i ; j++)
a[i*j]=0;
for(i=3; i<=n ; i+=2)
if (a[i]) nr++;
fout<<nr;
return 0;
}