Cod sursa(job #733052)
Utilizator | Iordan Vlad Vladinho97 | Data | 11 aprilie 2012 13:15:44 |
---|---|---|---|
Problema | Fractii | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.56 kb |
#include<fstream>
using namespace std;
int p[1000];
int t[1000];
int main()
{
int n,nr;
long long i,j,s;
ifstream f("fractii.in");
ofstream g("fractii.out");
f>>n;
for(i=2;i<=n;i++)
{
nr=1;
if(p[i]==0)
{
t[i]++;
for(j=i+i;j<=n;j+=i)
{
nr++;
t[j]++;
if((nr!=i)&&(p[j]!=-1))
p[j]=1;
else
{
p[j]=-1;
nr=0 ;
}
}
}
}
s=0;
for(i=1;i<=n;i++)
{
if(p[i]!=-1)
{
if(t[i]%2==0)
s+=(n/i)*((n/i)-1)/2;
else
s-=(n/i)*((n/i)-1)/2;
}
}
g<<2*s+1;
}