Cod sursa(job #516885)
Utilizator | Data | 26 decembrie 2010 20:45:50 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.3 kb |
#include<iostream>
#include<fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int main(){
long n,i,j,a=0,v[1000001];
f>>n;
for(i=2;i<=n;i++) v[i]=i-1;
for(i=2;i<=n;i++){
a=a+v[i];
for(j=2*i;j<=n;j=j+i) v[j]=v[j]-v[i];}
g<<a*2+1;
return 0;
}