#include<iostream>
#include<vector>
#include<algorithm>
#include<cassert>
#include<atcoder/modint>
using namespace std;
#include<vector>
template<typename T>
struct combination{
	vector<T>fac,ifac;
	combination(size_t N=0):fac(1,1),ifac(1,1)
	{
		make_table(N);
	}
	void make_table(size_t N)
	{
		if(fac.size()>N)return;
		size_t now=fac.size();
		N=max(N,now*2);
		fac.resize(N+1);
		ifac.resize(N+1);
		for(size_t i=now;i<=N;i++)fac[i]=fac[i-1]*i;
		ifac[N]=1/fac[N];
		for(size_t i=N;i-->now;)ifac[i]=ifac[i+1]*(i+1);
	}
	T factorial(size_t n)
	{
		make_table(n);
		return fac[n];
	}
	T invfac(size_t n)
	{
		make_table(n);
		return ifac[n];
	}
	T P(size_t n,size_t k)
	{
		if(n<k)return 0;
		make_table(n);
		return fac[n]*ifac[n-k];
	}
	T C(size_t n,size_t k)
	{
		if(n<k)return 0;
		make_table(n);
		return fac[n]*ifac[n-k]*ifac[k];
	}
	T H(size_t n,size_t k)
	{
		if(n==0)return k==0?1:0;
		return C(n-1+k,k);
	}
};
using mint=atcoder::modint998244353;
combination<mint>C;
int N,M,A[2<<17];
vector<pair<int,int> >a;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int T;
	cin>>T;
	for(;T--;)
	{
		cin>>N>>M;
		for(int i=0;i<N;i++)cin>>A[i];
		sort(A,A+N);
		a.clear();
		for(int i=0;i<N;i++)
		{
			if(a.empty()||a.back().first<A[i])a.push_back(make_pair(A[i],1));
			else a.back().second++;
		}
		int L=0,R=0;
		mint way=1;
		int cnt=0;
		for(int i=a.size()-1;i>=1;i--)
		{
			int val=a[i].first;
			int l=max(N-L-val,0),r=max(N-R-val,0);
			if(L>N-L-l)l=0;
			if(R>N-R-r)r=0;
			if(l>=1&&r>=1&&l+r==a[i].second)
			{//use l,r
				way*=C.C(l+r,l);
				L+=l,R+=r;
				cnt+=2;
				if(L<R)swap(L,R);
			}
			else if(l==a[i].second&&r==a[i].second)
			{
				assert(L==R);
				way*=2;
				L+=l;
				cnt++;
			}
			else if(l==a[i].second)
			{
				L+=l;
				cnt++;
			}
			else if(r==a[i].second)
			{
				R+=r;
				cnt++;
				if(L<R)swap(L,R);
			}
			else
			{
				way=0;
				break;
			}
		}
		mint ans=0;
		int val=a[0].first;
		if(max(L,R)==val)
		{
			ans+=way*C.C(M,cnt+1);
		}
		{
			int x=val-L;
			int y=val-R;
			if(x>=1&&y>=1&&L<=y+R&&L+x>=R&&x+y==a[0].second)
			{
				ans+=way*C.C(x+y,x)*C.C(M,cnt+2);
			}
		}
		cout<<ans.val()<<"\n";
	}
}