#include <bits/stdc++.h>
using namespace std;
#define x first
#define y second
typedef long long ll;
typedef pair<int, int> pii;
void solve() {
    int n, d; cin >> n >> d;
    vector<int> a(n);
    int sum = 0;
    for (auto &x: a) cin >> x, sum += x;
    sort(a.begin(), a.end());
    if (d == 1) {
        ll ans = 0;
        ans = (ll)(sum - 1) * sum / 2;
        cout << ans << '\n';
    }
    else if (d == 2) {
        ll ans = 0;
        for (auto x: a) {
            ans += (ll)x * (sum - x);
        }
        ans /= 2;
        cout << ans << '\n';
    } else {
        ll ans = 0;
        for (int i = 0; i < n; i ++ )
            ans += (ll)a[i] * (n - i - 1);
        cout << ans << '\n';
    }
}
int main() {
    cin.tie(0) -> sync_with_stdio(0);
    int _; cin >> _;
    while (_ -- )
        solve();
    return 0;
}