#include <bits/stdc++.h>
using namespace std;

const int mod = 998244353;

// modint
template <std::uint_fast64_t Modulus> class modint {
  using u64 = std::uint_fast64_t;

public:
  u64 a;

  constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
  constexpr u64 &value() noexcept { return a; }
  constexpr const u64 &value() const noexcept { return a; }
  constexpr modint operator+(const modint rhs) const noexcept {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint rhs) const noexcept {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint rhs) const noexcept {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint rhs) const noexcept {
    return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint rhs) noexcept {
    a += rhs.a;
    if (a >= Modulus) {
      a -= Modulus;
    }
    return *this;
  }
  constexpr modint &operator-=(const modint rhs) noexcept {
    if (a < rhs.a) {
      a += Modulus;
    }
    a -= rhs.a;
    return *this;
  }
  constexpr modint &operator*=(const modint rhs) noexcept {
    a = a * rhs.a % Modulus;
    return *this;
  }
  constexpr modint &operator/=(modint rhs) noexcept {
    u64 exp = Modulus - 2;
    while (exp) {
      if (exp % 2) {
        *this *= rhs;
      }
      rhs *= rhs;
      exp /= 2;
    }
    return *this;
  }
};
using mint = modint<mod>;
using vm = vector<mint>;
using vvm = vector<vm>;

ostream& operator << (ostream& os, const mint v){
os << v.value(); return os;
}

template <class T, class U> constexpr T power(T x, U exp) {
  T ret = static_cast<T>(1);
  while (exp) {
    if (exp % static_cast<U>(2) == static_cast<U>(1))
      ret *= x;
    exp /= static_cast<U>(2);
    x *= x;
  }
  return ::std::move(ret);
}

// 配列 x から目的関数値 f(x) を計算
mint calculate_objective_mod(vector<int> &x, vector<int> &A, int K){
    int N = A.size();

    int A_sum = 0;
    for(int i=0;i<N;i++) A_sum += A[i];

    mint res = 1;
    for(int i=1;i<=K;i++) res *= i;
    for(int i=0;i<N;i++){
        for(int j=1;j<=x[i];j++) res /= j;
    }

    for(int i=0;i<N;i++){
        mint y = A[i];
        y /= A_sum;
        for(int j=1;j<=x[i];j++) res *= y;
    }
    
    return res;
}

// priority_queue に入れる構造体
struct dat{
    int idx, A_val, x_val;
    bool operator< (const dat &right)const{
        return A_val * (right.x_val + 1) < right.A_val * (x_val + 1);
    }
};

int N_sum = 0;
int K_sum = 0;

void solve(){

    int N, K;
    cin >> N >> K;

    assert(1 <= N and N <= 100000);
    assert(1 <= K and K <= 100000);

    N_sum += N;
    K_sum += K;

    vector<int> A(N);
    for(int i=0;i<N;i++) cin >> A[i];

    for(int i=0;i<N;i++) assert(1 <= A[i] and A[i] <= 1000);

    vector<int> x(N, 0);

    priority_queue<dat> pq;
    for(int i=0;i<N;i++) pq.push(dat{i, A[i], x[i]});

    for(int i=0;i<K;i++){
        auto p = pq.top();pq.pop();
        x[p.idx]++;
        pq.push(dat{p.idx, A[p.idx], x[p.idx]});
    }
    
    mint res = calculate_objective_mod(x, A, K);

    cout << res << endl;

    return;
}

int main(){
    int T;
    cin >> T;

    assert(1 <= T and T <= 100);

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

    assert(1 <= N_sum and N_sum <= 100000);
    assert(1 <= K_sum and K_sum <= 100000);
}