题解：P11616 瓦解

#include<bits/stdc++.h>
// 7 10
// 9 23
// 1 6 7 8 9 20
typedef long long ll;
using namespace std;
int T;
int n,m;
ll a[10000010];
ll fac[10000010];
ll inv[10000010];
ll finv[10000010];
const ll mod=998244353;
ll fastpow(ll a, ll b) {
	ll ans = 1, base = a;
	while (b != 0) {
		if (b & 1)
			ans = (ans * base % mod) % mod;
		base = (base * base) % mod;
		b >>= 1;
	}
	ans %= mod;
	return ans;
}

ll C(ll n,ll m){
	if(m<0||m>n)return 0;
	return fac[n]*finv[n-m]%mod*finv[m]%mod;
}
int main(){
	inv[1]=1;
    for(int i=2;i<=10000000;i++)inv[i]=((mod-mod/i)*inv[mod%i])%mod;
	fac[0]=finv[0]=1;
	for(int i=1;i<=10000000;i++)fac[i]=fac[i-1]*i%mod,finv[i]=finv[i-1]*inv[i]%mod;
	cin>>T;
	while(T--){
		ll cnt=0;
		scanf("%d%d",&n,&m);
		for(int i=1;i<=n;i++){
			scanf("%lld",&a[i]);
			if(a[i]<=a[i-1]){
				cnt++;
			}
		}
		cnt++;
//		if(m<cnt){
//			puts("0");
//			continue;
//		}
//		puts("Run");
		ll ans=0;
		for(int i=cnt;i<=m;i++){
			ans+=C(n-cnt,i-cnt);
			ans%=mod;
		}
		cout<<ans%mod<<endl;
		
	}
}