1538B - Friends and Candies - CodeForces Solution

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};


void solve() {
    ll n;
    cin >> n;
    vector<ll> a(n);

    ll s = 0;
    for (ll i = 0; i < n; ++i) {
        cin >> a[i];
        s += a[i];
    }

    if (s % n != 0) {
        cout << -1 << "\n";
        return;
    }

    ll ans = 0;

    for (auto x: a) {
        ans += (x > s / n);
    }

    cout << ans << "\n";
}


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    ll tst = 1;
    cin >> tst;

    while (tst--) {
        solve();
    }


    return 0;
}