Cod sursa(job #289420)

Utilizator c_e_manuEmanuel Cinca c_e_manu Data 26 martie 2009 18:53:05
Problema Fractii Scor 100
Compilator cpp Status done
Runda aa Marime 0.34 kb
Raporteaza aceasta sursa 
#include<stdio.h>
long long phi[1000001],i,j,n;
int main()
{       freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%lld",&n);
	for(i=2;i<=n;i++)       phi[i]=i-1;
	for(i=2;i<=n;i++)
		for(j=2*i;j<=n;j+=i)    phi[j]-=phi[i];
	j=0;
	for(i=2;i<=n;i++) j+=phi[i];
	printf("%lld",j*2+1);
        return 0;
}