Cod sursa(job #551397)

Utilizator Eugen01Vasilescu Eugen Eugen01 Data 10 martie 2011 18:47:31
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include<stdio.h>
#include<math.h>
int j,i,n,a[1000000];
long long s;

int main()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%d",&n);
	
	for (i=1;i<=n;i++)
		a[i]=i-1;
	
	for (i=2;i<=n;i++)
	{
		s+=(2*a[i]);
		for (j=2*i;j<=n;j+=i)
			a[j]-=a[i];
	}
	
	printf("%lld\n",++s);
	return 0;
}