// #define _GLIBCXX_DEBUG
#pragma GCC optimize("O2,no-stack-protector,unroll-loops,fast-math")
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < int(n); i++)
#define per(i, n) for (int i = (n)-1; 0 <= i; i--)
#define rep2(i, l, r) for (int i = (l); i < int(r); i++)
#define per2(i, l, r) for (int i = (r)-1; int(l) <= i; i--)
#define each(e, v) for (auto& e : v)
#define MM << " " <<
#define pb push_back
#define eb emplace_back
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define sz(x) (int)x.size()
template <typename T> void print(const vector<T>& v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << (i == n - 1 ? '\n' : ' ');
    if (v.empty()) cout << '\n';
}
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <typename T> bool chmax(T& x, const T& y) {
    return (x < y) ? (x = y, true) : false;
}
template <typename T> bool chmin(T& x, const T& y) {
    return (x > y) ? (x = y, true) : false;
}
template <class T>
using minheap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template <class T> using maxheap = std::priority_queue<T>;
template <typename T> int lb(const vector<T>& v, T x) {
    return lower_bound(begin(v), end(v), x) - begin(v);
}
template <typename T> int ub(const vector<T>& v, T x) {
    return upper_bound(begin(v), end(v), x) - begin(v);
}
template <typename T> void rearrange(vector<T>& v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

// __int128_t gcd(__int128_t a, __int128_t b) {
//     if (a == 0)
//         return b;
//     if (b == 0)
//         return a;
//     __int128_t cnt = a % b;
//     while (cnt != 0) {
//         a = b;
//         b = cnt;
//         cnt = a % b;
//     }
//     return b;
// }

long long extGCD(long long a, long long b, long long& x, long long& y) {
    if (b == 0) {
        x = 1;
        y = 0;
        return a;
    }
    long long d = extGCD(b, a % b, y, x);
    y -= a / b * x;
    return d;
}

struct Union_Find_Tree {
    vector<int> data;
    const int n;
    int cnt;
 
    Union_Find_Tree(int n) : data(n, -1), n(n), cnt(n) {}
 
    int root(int x) {
        if (data[x] < 0) return x;
        return data[x] = root(data[x]);
    }
 
    int operator[](int i) { return root(i); }
 
    bool unite(int x, int y) {
        x = root(x), y = root(y);
        if (x == y) return false;
        if (data[x] > data[y]) swap(x, y);
        data[x] += data[y], data[y] = x;
        cnt--;
        return true;
    }
 
    int size(int x) { return -data[root(x)]; }
 
    int count() { return cnt; };
 
    bool same(int x, int y) { return root(x) == root(y); }
 
    void clear() {
        cnt = n;
        fill(begin(data), end(data), -1);
    }
};

template <int mod> struct Mod_Int {
    int x;

    Mod_Int() : x(0) {}

    Mod_Int(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    static int get_mod() { return mod; }

    Mod_Int& operator+=(const Mod_Int& p) {
        if ((x += p.x) >= mod) x -= mod;
        return *this;
    }

    Mod_Int& operator-=(const Mod_Int& p) {
        if ((x += mod - p.x) >= mod) x -= mod;
        return *this;
    }

    Mod_Int& operator*=(const Mod_Int& p) {
        x = (int)(1LL * x * p.x % mod);
        return *this;
    }

    Mod_Int& operator/=(const Mod_Int& p) {
        *this *= p.inverse();
        return *this;
    }

    Mod_Int& operator++() { return *this += Mod_Int(1); }

    Mod_Int operator++(int) {
        Mod_Int tmp = *this;
        ++*this;
        return tmp;
    }

    Mod_Int& operator--() { return *this -= Mod_Int(1); }

    Mod_Int operator--(int) {
        Mod_Int tmp = *this;
        --*this;
        return tmp;
    }

    Mod_Int operator-() const { return Mod_Int(-x); }

    Mod_Int operator+(const Mod_Int& p) const { return Mod_Int(*this) += p; }

    Mod_Int operator-(const Mod_Int& p) const { return Mod_Int(*this) -= p; }

    Mod_Int operator*(const Mod_Int& p) const { return Mod_Int(*this) *= p; }

    Mod_Int operator/(const Mod_Int& p) const { return Mod_Int(*this) /= p; }

    bool operator==(const Mod_Int& p) const { return x == p.x; }

    bool operator!=(const Mod_Int& p) const { return x != p.x; }

    Mod_Int inverse() const {
        assert(*this != Mod_Int(0));
        return pow(mod - 2);
    }

    Mod_Int pow(long long k) const {
        Mod_Int now = *this, ret = 1;
        for (; k > 0; k >>= 1, now *= now) {
            if (k & 1) ret *= now;
        }
        return ret;
    }

    friend ostream& operator<<(ostream& os, const Mod_Int& p) {
        return os << p.x;
    }

    friend istream& operator>>(istream& is, Mod_Int& p) {
        long long a;
        is >> a;
        p = Mod_Int<mod>(a);
        return is;
    }
};

ll mpow2(ll x, ll n, ll mod) {
    ll ans = 1;
    x %= mod;
    while (n != 0) {
        if (n & 1) ans = ans * x % mod;
        x = x * x % mod;
        n = n >> 1;
    }
    ans %= mod;
    return ans;
}

template <typename T> T modinv(T a, const T& m) {
    T b = m, u = 1, v = 0;
    while (b > 0) {
        T t = a / b;
        swap(a -= t * b, b);
        swap(u -= t * v, v);
    }
    return u >= 0 ? u % m : (m - (-u) % m) % m;
}

ll divide_int(ll a, ll b) {
    if (b < 0) a = -a, b = -b;
    return (a >= 0 ? a / b : (a - b + 1) / b);
}

// const int MOD = 1000000007;
const int MOD = 998244353;
using mint = Mod_Int<MOD>;

mint mpow(mint x, ll n) {
    bool rev = n < 0;
    n = abs(n);
    mint ans = 1;
    while (n != 0) {
        if (n & 1) ans *= x;
        x *= x;
        n = n >> 1;
    }
    return (rev ? ans.inverse() : ans);
}

// ----- library -------
template <typename T>
struct Combination {
    static vector<T> _fac, _ifac;

    Combination() {}

    static void init(int n) {
        _fac.resize(n + 1), _ifac.resize(n + 1);
        _fac[0] = 1;
        for (int i = 1; i <= n; i++) _fac[i] = _fac[i - 1] * i;
        _ifac[n] = _fac[n].inverse();
        for (int i = n; i >= 1; i--) _ifac[i - 1] = _ifac[i] * i;
    }

    static T fac(int k) { return _fac[k]; }

    static T ifac(int k) { return _ifac[k]; }

    static T inv(int k) { return fac(k - 1) * ifac(k); }

    static T P(int n, int k) {
        if (k < 0 || n < k) return 0;
        return fac(n) * ifac(n - k);
    }

    static T C(int n, int k) {
        if (k < 0 || n < k) return 0;
        return fac(n) * ifac(n - k) * ifac(k);
    }

    // n 個の区別できる箱に、k 個の区別できない玉を入れる場合の数
    static T H(int n, int k) {
        if (n < 0 || k < 0) return 0;
        return k == 0 ? 1 : C(n + k - 1, k);
    }

    // n 個の区別できる玉を、k 個の区別しない箱に、各箱に 1 個以上玉が入るように入れる場合の数
    static T second_stirling_number(int n, int k) {
        T ret = 0;
        for (int i = 0; i <= k; i++) {
            T tmp = C(k, i) * T(i).pow(n);
            ret += ((k - i) & 1) ? -tmp : tmp;
        }
        return ret * ifac(k);
    }

    // n 個の区別できる玉を、k 個の区別しない箱に入れる場合の数
    static T bell_number(int n, int k) {
        if (n == 0) return 1;
        k = min(k, n);
        vector<T> pref(k + 1);
        pref[0] = 1;
        for (int i = 1; i <= k; i++) {
            if (i & 1) {
                pref[i] = pref[i - 1] - ifac(i);
            } else {
                pref[i] = pref[i - 1] + ifac(i);
            }
        }
        T ret = 0;
        for (int i = 1; i <= k; i++) ret += T(i).pow(n) * ifac(i) * pref[k - i];
        return ret;
    }
};

template <typename T>
vector<T> Combination<T>::_fac = vector<T>();

template <typename T>
vector<T> Combination<T>::_ifac = vector<T>();
// ----- library -------

int main() {
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    cout << fixed << setprecision(15);

    using comb = Combination<mint>;
    comb::init(2e5 + 10);
    int T;
    cin >> T;
    while (T--) {
        int n, m;
        cin >> n >> m;
        vector<int> a(n);
        rep(i, n) cin >> a[i];
        vector<int> cnt(n, 0);
        rep(i, n) cnt[a[i]]++;
        int nl = 0, nr = 0, sum = n, c = 0;
        mint ans = 1;
        per(i, n) {
            if (!cnt[i])
                continue;
            sum -= cnt[i];
            if (i == max(nl, sum + nr)) {
                if (i == max(nr, sum + nl))
                    ans *= 2;
                nl += cnt[i], c++;
            }
            else if (i == max(nr, sum + nl))
                nr += cnt[i], c++;
            else if (i == sum + cnt[i] / 2 + nr && i == sum + cnt[i] / 2 + nl)
                nl += cnt[i] / 2, nr += cnt[i] / 2, c += 2, ans *= comb::C(cnt[i], cnt[i] / 2);
            else {
                ans = 0;
                break;
            }
            // cout << ans << ' ';
        }
        ans *= comb::C(m, c);
        cout << ans / 2 << '\n';
    }
}