#include <cassert>
#include <queue>
#include <vector>
#include <numeric>
#include <iostream>
using namespace std;
constexpr int M = 998244353;

long long modexp(int x, long long e, int m) {
    long long ans = 1, p = x % m;
    while (e > 0) {
        if (e % 2 != 0) ans = (ans * p) % m;
        p = (p * p) % m;
        e >>= 1;
    }
    return ans;
}

class ModComb {
    long long *fact, *facti;
    const int mod;
public:
    explicit ModComb(int n, int m) : mod(m) {
        fact = new long long[n+1];
        facti = new long long[n+1];
        fact[0] = 1; facti[0] = 1;
        for (int i = 1; i <= n; i++) fact[i] = (fact[i-1] * i) % m;
        // calc 1/n!
        long long &inv = facti[n], pw = fact[n];
        inv = 1;
        for (int e = mod-2; e > 0; e /= 2) {
            if (e&1) inv = inv * pw % mod;
            pw = pw * pw % mod;
        }
        for (int i = n-1; i > 0; i--) facti[i] = (facti[i+1] * (i+1)) % m;
    }

    ~ModComb() {
        if (fact) delete[] fact;
        if (facti) delete[] facti;
    }

    long long getFact(int n) const {
        return fact[n];
    }

    long long getFactInv(int n) const {
        return facti[n];
    }

    long long getComb(int n, int k) const {
        if (n < 0 || k < 0 || k > n) return 0;
        return fact[n] * facti[k] % mod * facti[n-k] % mod;
    }

    long long getPerm(int n, int k) const {
        if (n < 0 || k < 0 || k > n) return 0;
        return fact[n] * facti[n-k] % mod;
    }
};

int main() {
    int t; cin >> t;
    ModComb mc(100100, M);
    while (t--) {
        int n, k; cin >> n >> k;
        vector<int> a(n);
        for (int i = 0; i < n; i++) cin >> a[i];
        struct entry {
            int i, m, a;
            entry(int i, int m, int a) : i(i), m(m), a(a) {}
            bool operator<(const entry& rhs) const {
                return a * rhs.m < rhs.a * m;
            }
        };
        priority_queue<entry> pq;
        for (int i = 0; i < n; i++) pq.emplace(i, 1, a[i]);
        vector<int> f(n);
        int sum = 0;
        while (sum < k) {
            auto [i, m, a] = pq.top();
            pq.pop();
            sum++;
            f[i]++;
            assert(f[i] == m);
            pq.emplace(i, m+1, a);
        }

        long long p = modexp(accumulate(a.begin(), a.end(), 0), M-k-1, M);
        int s = k;
        for (int i = 0; i < n; i++) {
            p = p * mc.getComb(s, f[i]) % M;
            p = p * modexp(a[i], f[i], M) % M;
            s -= f[i];
        }
        assert(s == 0);
        cout << p << endl;
    }
}