Cod sursa(job #830579)

Utilizator Stefanescu_MihaiStefanescu Mihai-Nicolae Stefanescu_Mihai Data 7 decembrie 2012 09:06:28
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.33 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
long long m=0;
unsigned int i,k,n,a[1000003];
int main()
{
	ifstream f1("fractii.in");
	f1>>n;
	f1.close();
	ofstream f2("fractii.out");
	for (i=2;i<=n;i++) a[i]=i-1;
	for (i=2;i<=n;i++)
	{
		m+=a[i];
		for (k=i+i;k<=n;k+=i)
			a[k]-=a[i];
	}
	f2<<2*m+1;
	f2.close();
	return 0;
}