Cod sursa(job #903705)

Utilizator taigi100Cazacu Robert taigi100 Data 2 martie 2013 16:51:17
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.33 kb
Raporteaza aceasta sursa 
#include<stdio.h>
int v[1000001];
long long suma;
int main()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	int n;
	scanf("%d",&n);
	for(int i=1;i<=n;++i)
		v[i]=i-1;
	for(int i=2;i<=n;++i)
		for(int j=2*i;j<=n;j+=i)
			v[j]-=v[i];
	for(int i=1;i<=n;i++)
		suma+=v[i]*2;
	printf("%lld",suma+1);
}