#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

const ll MOD = 998244353;

class ModInt{
    public:
    ll v;
    ModInt(ll _v = 0){
        if(_v < 0) _v = (v%MOD)+MOD;
        if(_v >= MOD) _v %= MOD;
        v = _v;
    }
    ModInt operator+(ll n){
        return ModInt((v+n)%MOD);
    }
    ModInt operator-(ll n){
        return ModInt((v-n+MOD)%MOD);
    }
    ModInt operator*(ll n){
        if(n >= MOD) n %= MOD;
        return ModInt((v*n)%MOD);
    }
    ModInt operator/(ll n){
        return ModInt((ModInt(n).inv()*v).v%MOD);
    }

    void operator+=(ll n){
        v = (v+n)%MOD;
    }
    void operator-=(ll n){
        v = (v-n+MOD)%MOD;
    }
    void operator*=(ll n){
        v = (v*n+MOD)%MOD;
    }
    
    
    ModInt operator+(ModInt n){
        return ModInt((v+n.v)%MOD);
    }
    ModInt operator-(ModInt n){
        return ModInt((v-n.v+MOD)%MOD);
    }
    ModInt operator*(ModInt n){
        return ModInt((v*n.v)%MOD);
    }
    ModInt operator/(ModInt n){
        return ModInt((n.inv()*v).v%MOD);
    }

    void operator+=(ModInt n){
        v = (v+n.v)%MOD;
    }
    void operator-=(ModInt n){
        v = (v-n.v+MOD)%MOD;
    }
    void operator*=(ModInt n){
        v = (v*n.v)%MOD;
    }

    void operator=(ModInt n){
        v = n.v;
    }
    bool operator==(ModInt n){
        return v == n.v;
    }
    bool operator!=(ModInt n){
        return v != n.v;
    }
    void operator=(ll n){
        v = n%MOD;
    }

    ModInt inv(){
        if(v == 1) return ModInt(1);
        else return ModInt(MOD-ModInt(MOD%v).inv().v*(MOD/v)%MOD);
    }
};

ostream& operator<<(ostream& os, const ModInt& m){
    os << m.v;
    return os;
}

istream & operator >> (istream &in,  ModInt &m){
    in >> m.v;
    return in;
}

ModInt pow(ModInt a, ll n) {
    assert(n >= 0);
	ModInt ans = 1;
	ModInt tmp = a;
	for (int i = 0; i <= 60; i++) {
		ll m = (ll)1 << i;
		if (m & n) {
		ans *= tmp;
		}
		tmp *= tmp;
	}
	return ans;
}

template <typename T>
class frac{
    public:
    T n, d;
    frac(T _n, T _d){
        T g = gcd(_n, _d);
        n = _n/g;
        d = _d/g;
        if(d < 0) {
            d *= -1;
            n *= -1;
        }
    }
    frac(){
        n = 1;
        d = 1;
    }
    frac operator+(frac f){
        return frac(n*f.d+d*f.n, f.d*d);
    }
    frac operator-(frac f){
        return frac(n*f.d-d*f.n, f.d*d);
    }
    frac operator*(frac f){
        return frac(f.n*n, f.d*d);
    }
    frac inv(){
        return frac(d, n);
    }
    bool operator<(frac f){
        if(d*f.d < 0) return n*f.d-d*f.n > 0;
        else return n*f.d-d*f.n < 0;
    }
    bool operator>(frac f){
        if(d*f.d < 0) return n*f.d-d*f.n < 0;
        else return n*f.d-d*f.n > 0;
    }
    bool operator==(frac f){
        return n*f.d-d*f.n == 0;
    }
    void operator+=(frac f){
        n = n*f.d+d*f.n, d = f.d*d;
        reduction();
    }
    void operator-=(frac f){
        n = n*f.d-d*f.n, d = f.d*d;
        reduction();
    }
    void reduction(){
        T g = gcd(n, d);
        n /= g, d /= g;
    }
};

template <typename T>
bool operator<(const frac<T> f1, const frac<T> f2){
    if(f1.d*f2.d < 0) return f1.n*f2.d-f1.d*f2.n > 0;
    else return f1.n*f2.d-f1.d*f2.n < 0;
}

template <typename T>
bool operator>(const frac<T> f1, const frac<T> f2){
    if(f1.d*f2.d < 0) return f1.n*f2.d-f1.d*f2.n > 0;
    else return f1.n*f2.d-f1.d*f2.n > 0;
}

template <typename T>
bool operator==(const frac<T> f1, const frac<T> f2){
    return f1.n*f2.d-f1.d*f2.n == 0;
}

using mint = ModInt;
using F = frac<int>;
using Pfi = pair<F, int>;

void solve(){
    int n, k; cin >> n >> k;
    vector<int> a(n);
    for(int i = 0; i < n; i++) cin >> a[i];
    int sum = accumulate(a.begin(), a.end(), 0);
    vector<F> p(n);
    for(int i = 0; i < n; i++) p[i] = F(a[i], sum);
    mint ans = 1;
    for(int i = 1; i <= k; i++) ans *= i;
    priority_queue<Pfi> que;
    vector<int> cur(n, 1);
    for(int i = 0; i < n; i++){
        que.push(Pfi(p[i], i));
    }
    while(k--){
        auto [p, i] = que.top(); que.pop();
        ans *= p.n;
        ans = ans/p.d;
        cur[i]++;
        if(cur[i] <= a[i]){
            que.push(Pfi(F(a[i], sum*cur[i]), i));
        }
    }
    cout << ans << endl;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int t; cin >> t;
    while(t--) solve();
}