#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>


using namespace std;
using namespace __gnu_pbds;

#define rep(i,a,n) for (int i=(a);i<(n);i++)
#define per(i,a,n) for (int i=(n)-1;i>=(a);i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) (int)x.size()

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int,int> pii;
typedef pair<ll,ll>pll;
typedef vector<pii> vpii;

template<typename T>
T getint() {
    T x=0,p=1;
    char ch;
    do{ch=getchar();}while(ch <= ' ');
    if(ch=='-')p=-1,ch=getchar();
    while(ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
    return x*p;
}

mt19937 gen(chrono::system_clock::now().time_since_epoch().count());

template<typename T1,typename T2>bool umin(T1 &x,const T2&y){if(x>y)return x=y,true;return false;}
template<typename T1,typename T2>bool umax(T1 &x,const T2&y){if(x<y)return x=y,true;return false;}

const int maxn=(int)1e5+10;
const int inf=(int)1e6+5;
const int mod=(int)1e9+7;
const ll llinf=(ll)1e12+5;
const ld pi=acos(-1.0);

vi g[maxn];
ld dp[maxn][2];
int a[maxn];
ld b[maxn];

void solve(int v,int p=-1){
    vi child;
    for(int x:g[v])if(x!=p){
        solve(x,v);
        child.pb(x);
    }

    dp[v][0]=dp[v][1]=-llinf;

    vector <int> c;
    for(int x:child){
        if(max(dp[x][0],dp[x][1])<0)c.pb(x);
    }
    if(c.size()>2)return;
    if(c.size()==0){
        dp[v][0]=b[v];
        for(int x:child)umax(dp[v][0],dp[x][0]+b[v]);
        pair<ld,ld> twomax=mp(-llinf,-llinf);
        for(int x:child){
            if(dp[x][0]>twomax.fi){
                twomax.se=twomax.fi;
                twomax.fi=dp[x][0];
            }else umax(twomax.se,dp[x][0]);
        }
        umax(dp[v][1],twomax.fi+twomax.se+b[v]);
    }
    if(c.size()==2){
        dp[v][0]=-llinf;
        dp[v][1]=dp[c[0]][0]+dp[c[1]][0]+b[v];
        if(dp[v][1]<0)dp[v][1]=-llinf;
    }
    if(c.size()==1){
        dp[v][0]=b[v]+dp[c[0]][0];
        for(int x:child){
            if(x!=c[0])umax(dp[v][1],dp[c[0]][0]+b[v]+dp[x][0]);
        }
    }
    umax(dp[v][1],dp[v][0]);
}

int main() {
   // freopen("input.txt","r",stdin);
   // freopen("output.txt","w",stdout);
    ios_base::sync_with_stdio(0);
    int T;
    cin>>T;
    while(T--) {
        int n;
        cin>>n;
        rep(i,0,n)dp[i][0]=dp[i][1]=0, g[i].clear();
        rep(i,0,n)cin>>a[i];
        rep(i,0,n-1){
            int x,y;
            cin>>x>>y;
            --x;--y;
            g[x].pb(y);
            g[y].pb(x);
        }
        ld lf=0,rg=maxn;
        rep(j,0,42){
            ld md=(lf+rg)/2;
            rep(i,0,n)b[i]=a[i]-md;
            solve(0);
            if(dp[0][1]>=0)lf=md;
            else rg=md;
        }
        cout.precision(7);
        cout<<fixed << rg<<'\n';
    }
    return 0;
}