Cod sursa(job #1863767)

Utilizator stefanidisstefan27Stefanidis Stefan stefanidisstefan27 Data 31 ianuarie 2017 10:33:01
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.31 kb
Raporteaza aceasta sursa 
#include <fstream>

using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");

const int N=2000000;
bool c[N+1];

int main()
{
    int i,j,n,nr=0;
    in>>n;
    for(i=2; i*i<=n; i++)
		if(!c[i])
			for(j=i*i; j<=n; j+=i)
				c[j]=true;
	for(i=2; i<=n; i++)
		if(!c[i])
			nr++;
	out<<nr;
    return 0;
}