Cod sursa(job #1260912)

Utilizator justsomedudePalade Thomas-Emanuel justsomedude Data 11 noiembrie 2014 19:12:36
Problema Ciurul lui Eratosthenes Scor 30
Compilator cpp Status done
Runda Arhiva educationala Marime 0.35 kb
Raporteaza aceasta sursa 
#include<iostream>
#include<fstream>
using namespace std;
long long int a[2000005];
ifstream in ("ciur.in");
ofstream out("ciur.out");
int main ()
{    int n,i,j,k;
     in>>n;

for (i=3;i*i<=n;i=i+2)
	if (a[i]==0) 
		for (j=i*i;j<=n;j=j+2*i)
			a[j] =1;

k=1;

for (i=3;i<=n;i=i=i+2)
	if (a[i] == 0)
		k++;
		
		out<<k;
 
return 0;
}