#include using namespace std; typedef signed long long ll; #define _P(...) (void)printf(__VA_ARGS__) #define FOR(x,to) for(x=0;x<(to);x++) #define FORR(x,arr) for(auto& x:arr) #define FORR2(x,y,arr) for(auto& [x,y]:arr) #define ALL(a) (a.begin()),(a.end()) #define ZERO(a) memset(a,0,sizeof(a)) #define MINUS(a) memset(a,0xff,sizeof(a)) template bool chmax(T &a, const T &b) { if(a bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;} //------------------------------------------------------- const ll mo=998244353; int T,N,M; int C[202020]; ll comb(ll N_, ll C_) { const int NUM_=400001; static ll fact[NUM_+1],factr[NUM_+1],inv[NUM_+1]; if (fact[0]==0) { inv[1]=fact[0]=factr[0]=1; for (int i=2;i<=NUM_;++i) inv[i] = inv[mo % i] * (mo - mo / i) % mo; for (int i=1;i<=NUM_;++i) fact[i]=fact[i-1]*i%mo, factr[i]=factr[i-1]*inv[i]%mo; } if(C_<0 || C_>N_) return 0; return factr[C_]*fact[N_]%mo*factr[N_-C_]%mo; } void solve() { int i,j,k,l,r,x,y; string s; cin>>T; while(T--) { cin>>N>>M; FOR(i,N+2) C[i]=0; FOR(i,N) { cin>>x; C[x]++; } int L=0,R=0; ll ret=1; int num=0; for(i=N-1;i>=0;i--) if(C[i]) { int cur=C[i]; int lef=N-L-R-cur; if(lef==0) { if(max(L,R)==i) { num++; } else if(N%2==0&&i==N/2) { num+=2; ret=ret*comb(lef,N/2-L)%mo; } else { ret=0; } } else if(L==R) { if(L*2>=N||R*2>=N) ret=0; if(lef+L==i) { L+=cur; num++; ret=ret*2%mo; } else if(cur%2==0&&L+cur/2+lef==i) { L+=cur/2; R+=cur/2; ret=ret*comb(cur,cur/2)%mo; num+=2; } else { ret=0; } } else { if(L*2>=N||R*2>=N) ret=0; if(L+lef==i&&L+lef>=R) { R+=cur; num++; } else if(R+lef==i&&R+lef>=L) { L+=cur; num++; } else if((L+R+cur)%2==0&&abs(R-L)<=cur&&i==(N-lef)/2+lef) { ret=ret*comb(cur,(N-lef)/2-L)%mo; L=R=(N-lef)/2; num+=2; } else { ret=0; } } } ret=ret*comb(M,num)%mo; cout<