Cod sursa(job #396069)

Utilizator bugyBogdan Vlad bugy Data 14 februarie 2010 14:11:00
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.35 kb
Raporteaza aceasta sursa 
#include <fstream>
using namespace std;
int v[1000001],i,j,n;
long long nr=0;

FILE *f=fopen("fractii.in","r"), *g=fopen("fractii.out","w");
	
int main()
{
	fscanf(f,"%d",&n);
	
	for (i=2;i<=n;i++)
	{
		v[i]=v[i]+i-1;
		for (j=2*i;j<=n;j+=i)
			v[j]-=v[i];
		nr+=v[i];
	}
	
	fprintf(g,"%d\n",2*nr+1);
	
fclose(f);
fclose(g);
return 0;	
}