Pagini recente » Cod sursa (job #3261551) | Cod sursa (job #2671957) | Cod sursa (job #481242) | Cod sursa (job #1919209) | Cod sursa (job #3264569)
#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("pairs.in");
ofstream g("pairs.out");
long long n,v[100005],cnt,fr[1000005],sol[100005],m[100005],maxi=-1;
int main()
{
f>>n;
for(int i=1;i<=n;i++)
{
f>>v[i],fr[v[i]]++;
maxi=max(maxi,v[i]);
}
for(int i=maxi;i>=1;i--)
{
for(int j=i;j<=maxi;j+=i)
m[i]+=fr[j];
sol[i]=m[i]*(m[i]-1)/2;
for(int j=i*2;j<=maxi;j+=i)
sol[i]-=sol[j];
}
g<<sol[1];
return 0;
}