Cod sursa(job #3225814)
Utilizator | Cristea Beatrice Corina cristeabeatrice | Data | 19 aprilie 2024 08:04:32 |
---|---|---|---|
Problema | Pairs | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.6 kb |
#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
using namespace std;
ifstream f("pairs.in");
ofstream g("pairs.out");
long long n, ma=0, x, fr[1000000], ans[1000000];
int main()
{
f>>n;
for(int i=1; i<=n; i++)
{
f>>x;
fr[x]++;
ma = max(ma, x);
}
for(int cm=ma; cm>=1; cm--)
{
for(int i=cm; i<=ma; i=i+cm)
ans[cm]=ans[cm]+fr[i];
ans[cm] = ans[cm]*(ans[cm]-1)/2;
for(int i = 2*cm; i<=ma; i=i+cm)
ans[cm]=ans[cm]-ans[i];
}
g<<ans[1];
return 0;
}