//~ while (clock()<=69*CLOCKS_PER_SEC)
//~ #pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("O3")
//~ #pragma GCC target ("avx2")
//~ #pragma GCC optimize("Ofast")
//~ #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//~ #pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
  enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

#define shandom_ruffle random_shuffle

using ll=long long;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using vi=vector<int>;
using vll=vector<ll>;
const int nax=1000*1007;
const ll mod=998244353;

ll inv(ll v)
{
	if (v<=1)
		return v;
	return inv(mod%v)*(mod-mod/v)%mod;
}

struct node {
	int roz=1;
	ll wag;
	ll praw;
	ll mnopra=1;
	ll sumpra;
	ll sumwag;
	node *lew, *oj, *pra;
	node() { lew=pra=oj=NULL; }
};
void update(node *v) {
	if (v==NULL) return;
	v->roz=1;
	v->sumpra=0;
	v->sumwag=0;
	for (int h=0; h<2; h++) {
		if (v->lew!=NULL) {
			v->roz+=v->lew->roz;
			(v->lew->mnopra)=(v->lew->mnopra)*(v->mnopra)%mod;
			(v->sumpra)=((v->sumpra)+(v->lew->sumpra)*(v->lew->mnopra))%mod;
			(v->sumwag)=((v->sumwag)+(v->lew->sumwag)*(v->lew->mnopra))%mod;
		}
		swap(v->lew, v->pra);
	}
	(v->praw)=(v->praw)*(v->mnopra)%mod;
	v->mnopra=1;
	(v->sumpra)=((v->sumpra)+(v->praw))%mod;
	(v->sumwag)=((v->sumwag)+(v->praw)*(v->wag))%mod;
}
node *merge(node *v, node *u) {
	if (v==NULL) return u;
	if (u==NULL) return v;	
	if (rand()%(v->roz+u->roz)<(v->roz)) {
		update(v);//czasem można usunąć
		v->pra=merge(v->pra, u);
		v->pra->oj=v;
		update(v);
		return v;
	} else {
		update(u);//czasem można usunąć
		u->lew=merge(v, u->lew);
		u->lew->oj=u;
		update(u);
		return u;
	}
}
pair <node*, node*> split(node *v, const function <bool(node*)> &is_left) {
	if (v==NULL)
		return make_pair(v, v);
	pair <node*, node*> ret;
	update(v);//czasem można usunąć
	v->oj=NULL;
	if (is_left(v)) {
		ret=split(v->pra, is_left);
		v->pra=ret.first;
		if (v->pra!=NULL)
			v->pra->oj=v;
		ret.first=v;
	} else {
		ret=split(v->lew, is_left);
		v->lew=ret.second;
		if (v->lew!=NULL)
			v->lew->oj=v;
		ret.second=v;
	}
	update(v);
	return ret;
}
ll gl_help;
function <bool(node*)> cut_v(int v) {
	gl_help=v;
	return [](node *u)->bool {
		int pom=1;
		if (u->lew!=NULL) pom+=u->lew->roz;
		if (pom>gl_help) return false;
		gl_help-=pom;
		return true;
	};
}
function <bool(node*)> cut_leq(ll v) {
	gl_help=v;
	return [](node *u)->bool {
		return (u->wag)<=gl_help;
	};
}
int position(node *v) {
	int ret=1;
	if (v->lew!=NULL) ret+=v->lew->roz;
	if (v->oj==NULL) return ret;
	return position(v->oj)+ret-(v->oj->lew==v)*(v->roz+1);
}

ll daj_sumpra(node *v)
{
	update(v);
	if (!v)
		return 0;
	return v->sumpra;
}

ll daj_sumwag(node *v)
{
	update(v);
	if (!v)
		return 0;
	return v->sumwag;
}

ll minimum(node *v)
{
	if (v->lew)
		return minimum(v->lew);
	return v->wag;
}

void przemnoz(node *v, ll w)
{
	if (!v)
		return;
	(v->mnopra)=(v->mnopra)*w%mod;
}

int n, korz;

ll tab[nax];

vi graf[nax];

ll minipod[nax];
node *dp[nax];

vector<pair<node*,int>> ciete[nax];
vll granice;

ll wyn;

void wypisz(node *v)
{
	if (!v)
		return;
	update(v);
	wypisz(v->lew);
	debug() << (v->wag) << " " << (v->praw);
	wypisz(v->pra);
}

void usun(node *v)
{
	if (!v)
		return;
	usun(v->lew);
	usun(v->pra);
	delete v;
}

bool mniej(int a, int b)
{
	return minipod[a]<minipod[b];
}

ll sumsuf[nax];

node *merge_smart(node *a, node *b)
{
	node *ret=NULL;
	while(a && b)
	{
		ll ma=minimum(a);
		ll mb=minimum(b);
		if (ma>mb)
		{
			swap(a, b);
			swap(ma, mb);
		}
		auto wez=split(a, cut_leq(mb));
		ret=merge(ret, wez.first);
		a=wez.second;
	}
	if (a)
		ret=merge(ret, a);
	if (b)
		ret=merge(ret, b);
	return ret;
}

void potnij(node *v, vector<pair<node*,int>> &wek)
{
	while(v)
	{
		ll x=minimum(v);
		int g=lower_bound(granice.begin(), granice.end(), x)-granice.begin();
		if (g==(int)granice.size())
		{
			wek.push_back({v, g});
			continue;
		}
		auto wez=split(v, cut_leq(granice[g]));
		wek.push_back({wez.first, g});
		v=wez.second;
	}
	for (int i=1; i<(int)wek.size(); i++)
		assert(wek[i].second!=wek[i-1].second);
}

void dfs1(int v, int oj)
{
	for (int &i : graf[v])
	{
		if (i==oj)
		{
			swap(i, graf[v].back());
			graf[v].pop_back();
			break;
		}
	}
	minipod[v]=tab[v];
	for (int i : graf[v])
	{
		dfs1(i, v);
		minipod[v]=min(minipod[v], minipod[i]);
	}
	sort(graf[v].begin(), graf[v].end(), mniej);
	granice.clear();
	for (int i : graf[v])
		granice.push_back(minipod[i]);
	for (int i : graf[v])
	{
		ciete[i].clear();
		potnij(dp[i], ciete[i]);
	}
	node *dod=NULL;
	int r=graf[v].size();
	for (int i=0; i<=r; i++)
		sumsuf[i]=0;
	for (int i : graf[v])
		for (auto j : ciete[i])
			sumsuf[j.second]+=daj_sumpra(j.first);
	for (int i=r-1; i>=0; i--)
		sumsuf[i]+=sumsuf[i+1];
	for (int i=0; i<=r; i++)
		sumsuf[i]%=mod;
	for (int i=0; i<r; i++)
	{
		ll x=sumsuf[i+1];
		for (auto j : ciete[graf[v][i]])
			if (j.second>i)
				x-=daj_sumpra(j.first);
		x%=mod;
		x+=mod;
		x%=mod;
		x=(x*inv(i+2))%mod;
		node *now=new node();
		now->wag=granice[i];
		now->praw=x;
		update(now);
		dod=merge(dod, now);
	}
	for (int i=0; i<r; i++)
	{
		for (auto j : ciete[graf[v][i]])
		{
			int mni=j.second;
			if (i<mni)
				mni--;
			przemnoz(j.first, inv(mni+1));
		}
	}
	for (int i : graf[v])
		for (auto j : ciete[i])
			dod=merge_smart(dod, j.first);
	
	auto wez=split(dod, cut_leq(tab[v]));
	node *now=new node();
	now->wag=tab[v];
	now->praw=daj_sumpra(wez.second)+1;
	update(now);
	usun(wez.second);
	dp[v]=merge(wez.first, now);
	
	wyn=(wyn+daj_sumwag(dp[v]))%mod;
}

void test()
{
	scanf("%d%d", &n, &korz);
	for (int i=1; i<=n; i++)
		scanf("%lld", &tab[i]);
	for (int i=1; i<=n; i++)
		graf[i].clear();
	for (int i=1; i<n; i++)
	{
		int a, b;
		scanf("%d%d", &a, &b);
		graf[a].push_back(b);
		graf[b].push_back(a);
	}
	wyn=0;
	dfs1(korz, 0);
	usun(dp[korz]);
	printf("%lld\n", wyn);
}

int main()
{
	int t;
	scanf("%d", &t);
	while(t--)
		test();
	return 0;
}