#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using mint = modint998244353;

constexpr int FACT_SIZE = 1000000;
mint Fact[FACT_SIZE + 1];
mint iFact[FACT_SIZE + 1];
const auto fact_init = [] {
    Fact[0] = mint::raw(1);
    for(int i = 1; i <= FACT_SIZE; ++i) {
        Fact[i] = Fact[i-1] * i;
    }
    iFact[FACT_SIZE] = Fact[FACT_SIZE].inv();
    for(int i = FACT_SIZE; i; --i) {
        iFact[i-1] = iFact[i] * i;
    }
    return false;
}();

mint comb(int n, int k) {
    if (k == 0) return mint::raw(1);
    assert(n >= 0 && k >= 0);
    if (k > n) return mint::raw(0);
    return Fact[n] * iFact[n - k] * iFact[k];
}

mint icomb(int n, int k) {
    return iFact[n] * Fact[n - k] * Fact[k];
}

mint fact(int n) {return Fact[n];}
mint perm(int n, int k) {
    assert(0 <= n);
    return Fact[n] * iFact[n - k];
}

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int tt;
  cin >> tt;
  while(tt--) {
    int n, m;
    cin >> n >> m;
    VI a(n);
    rep(i, n) cin >> a[i];
    sort(rall(a));
    int used = 0;
    mint ans = 1;
    int c0 = 0, c1 = 0;
    for(int i = 0; i < n;) {
      int j = i + 1;
      while(j < n && a[j] == a[i]) j++;
      int mx = a[i], cnt = j - i;
      if (c0 > c1) swap(c0, c1);
      if (c1 > mx) {
        ans = 0;
        break;
      }
      int D = n - j;
      if (c1 == mx) {
        if (c0 + D > mx) {
          ans = 0;
          break;
        }
        used++;
        c1 += cnt;
      } else if (c0 == c1) {
        if (D + c0 == mx) {
          used++;
          c1 += cnt;
          if (D > 0) ans *= 2;
        } else if (cnt % 2 == 0 && D + cnt / 2 + c0 == mx) {
          used += 2;
          c0 += cnt / 2;
          c1 += cnt / 2;
          ans *= comb(cnt, cnt / 2);
        } else {
          ans = 0;
          break;
        }
      } else if (D + c0 == mx) {
        used++;
        c1 += cnt;
      } else if (D + c1 == mx) {
        used++;
        c0 += cnt;
      } else {
        int x = mx - D - c0, y = mx - D - c1;
        if (x <= 0 || y <= 0 || x + y != cnt) {
          ans = 0;
          break;
        }
        used += 2;
        c0 += x;
        c1 += y;
        ans *= comb(x + y, x);
      }
      i = j;
    }
    if (ans.val()) ans *= comb(m, used);
    cout << ans.val() << '\n';
  }
}