Cod sursa(job #3291903)

Utilizator FRD233Fodor Rares-Costin FRD233 Data 6 aprilie 2025 10:29:50
Problema Pairs Scor 0
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.89 kb
#include <bits/stdc++.h>
using namespace std;
ifstream f("pairs.in");
ofstream g("pairs.out");
int F[100001],n,A[100001],v[50],sol,W[100001],pmax;
int c[100001];
int main()
{   f>>n;
    for(int i=1;i<=n;i++) f>>A[i];
    for(int i=2;i<=1001;i++)
        if(!c[i]) for(int j=i;j<=1001;j+=i) c[j]=i;
    sol=n*n;
    for(int i=1;i<=n;i++)
    {   int x=A[i];
        int k=0;
        while(x>1)
        {   int y=c[x];
            v[++k]=y;
            while(c[x]==y) x=x/y;
        }
        for(int j=1;j<(1<<k);j++)
        {   int p=1,nr=0;
            for(int l=0;l<k;l++)
                if((1<<l)&j) p=p*v[l+1],nr++;
            F[p]++;
            W[p]=nr;
            pmax=max(p,pmax);
        }
    }
    for(int i=1;i<=pmax;i++)
        if(W[i])
        {   if(W[i]%2) sol-=(F[i]*F[i]);
            else sol+=(F[i]*F[i]);
        }
    g<<sol/2<<'\n';
    return 0;
}