Untitled

mail@pastecode.io avatar
unknown
plain_text
a month ago
1.6 kB
7
Indexable
Never
#include <bits/stdc++.h>
#define endl "\n"
#define ll long long
#define sz(x) ((int) (x).size())
#define all(x) (x).begin(), (x).end()
#define Y cout<<"YES"<<endl
#define N cout<<"NO"<<endl
#define int long long
#define pb push_back
#define ff first
#define ss second
#define vi vector<int>
#define pii pair<int, int>
#define rep(i, a, b) for(int i = (a); i < (b); i++)

using namespace std;

vector<int> primes;
const int MAX = 100005;
bool isPrime[2 * MAX + 1];

void sieve() {
    for (int i = 0; i < 2 * MAX + 1; i++) {
        isPrime[i] = true;
    }
    
    isPrime[0] = isPrime[1] = false;
    
    for (int i = 2; i <= sqrt(2 * MAX); i++) {
        if (isPrime[i]) {
            for (int j = i * i; j <= 2 * MAX; j += i) {
                isPrime[j] = false;
            }
        }
    }
    
    for (int i = 2; i < 2 * MAX + 1; i++) {
        if (isPrime[i]) {
            primes.push_back(i);
        }
    }
}
void solve () {
    int n,maxm=LLONG_MIN; cin>>n;
    unordered_map<int, int> mp;
    for (int i=0; i<n; i++) {
        int x; cin>>x;
        mp[x]++;
        maxm = max(x, maxm);
    }
    int ans=0;
    for (auto &[val, cnt]: mp) {
        int x=val;
        for (int &y: primes) {
            int find = x*y;
            if (find > maxm) break;
            if (mp.find(find)!=mp.end()) {
                ans += (cnt * mp[find]);
            }
        }
    }
    cout << ans << "\n";
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t=1;
    cin>>t;
    sieve();
    //for (int i=0; i<10; i++) cout << primes[i] << " ";
    while(t--)
    {
        solve ();
    }
}