Cod sursa(job #3271011)

Utilizator poparobertpoparobert poparobert Data 25 ianuarie 2025 02:05:35
Problema Pairs Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.52 kb
#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("pairs.in");
ofstream g("pairs.out");
int n,cnt,m[1000005],fr[1000005],maxi=-1,x;
long long sol[1000005];
int main()
{
    f>>n;
    for(int i=1;i<=n;i++)
    {
        f>>x,fr[x]++;
        maxi=max(maxi,x);
    }
    for(int i=maxi;i>=1;i--)
    {
         for(int j=i;j<=maxi;j+=i)
        m[i]+=fr[j];
        sol[i]=1LL*m[i]*(m[i]+1)/2;
        for(int j=i*2;j<=maxi;j+=i)
            sol[i]-=sol[j];
    }
    g<<sol[1];
    return 0;
}