Cod sursa(job #669695)

Utilizator ephgstefana gal ephg Data 27 ianuarie 2012 16:01:44
Problema Fractii Scor 90
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.33 kb
Raporteaza aceasta sursa 
#include <cstdio>
long long  v[1000005];
int main () {
	long long n,rez=0;
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%lld",&n);
	for(int i=1;i<=n;++i)v[i]=i-1;
	for(int i=2;i<=n;++i){
		rez+=v[i];
		for(int j=i+i;j<=n;j+=i){
			v[j]-=v[i];
		}
	}
	printf("%lld",2LL*rez+1);
	return 0;
}