Cod sursa(job #520084)

Utilizator raduiris94Alexa Radu raduiris94 Data 7 ianuarie 2011 13:27:54
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include<iostream>
#include<fstream>
using namespace std;
long long  a[1000000];
int main()
{
	ifstream f("fractii.in");
	ofstream g("fractii.out");
	long long rez=0, n, i, j;
	f>>n;
	for(i=2; i<=n; i++)
		a[i]=i-1;
	for(i=2; i<=n; i++)
	{
		rez=rez+a[i];
		for(j=i*2; j<=n; j=j+i)
			a[j]=a[j]-a[i];
	}
	g<<2*rez+1;
	return 0;
}