Cod sursa(job #615003)

Utilizator matei_cChristescu Matei matei_c Data 8 octombrie 2011 12:13:29
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include<stdio.h>
int n,nr,phi[1000000];
int main()
{
	int i,j;
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%d",&n);
	for(i=1;i<=n;i++)
		phi[i]=i-1;
	for(i=1;i<=n/2;i++)
	{
		for(j=2*i;j<=n;j+=i)
			phi[j]-=phi[i];
	}	
	for(i=2;i<=n;i++)
		nr+=phi[i];
	printf("%d\n",2*nr+1);
	return 0;
}