11.Edge Deletion Questions using DFS

 #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;

template <class type1>

#define ll long long int

#define endl "\n"

#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>

using ordered_multiset = tree <type1, null_type, less_equal <type1>, rb_tree_tag, tree_order_statistics_node_update>;

 //ordered_multiset <ll> kek;(declaration for multiorder set)

// ordered_set o_set;(declaration)

//kek.order_of_key(i);(strictly less then i for multi order set)

//o_set.order_of_key(5) ;(strictly less then i for multi order set)

#define yes cout << "YES\n"

#define no cout << "NO\n"

#define mod 1000000007

ll POW(ll a,ll b)

{   ll ans=1;

   while(b>0)

   {   if(b%2)ans=(ans*a)%mod;

       b/=2;

       a=(a*a)%mod;

   }

   return ans;

}

vector<ll>adj[100000];

ll subtre[100000];

ll val[100000];

void dfs(ll node,ll par)

{

      subtre[node]=val[node];

         // cout<<subtre[node]<<" "<<val[node]<<endl;

      for(auto u:adj[node])

      {

          if(par==u)continue;

          dfs(u,node);

          subtre[node]+=subtre[u];

      }

}

int main()

{

    ios_base::sync_with_stdio(0);

    cin.tie(0);

    cout.tie(0);

   

     ll n,i;

     cin>>n;

     for(i=1;i<n;i++)

     {

         ll u,v;

         cin>>u>>v;

         adj[v].push_back(u);

         adj[u].push_back(v);

     }

     for(i=1;i<=n;i++)

     {

               cin>>val[i];

               cout<<val[i]<<" ";

     }

      dfs(1,-1);

      ll ans=0;

      //cout<<subtre[1]<<" ";

      for(i=2;i<=n;i++)

      {

              // cout<<subtre[i]<<" ";

         

           ll sum1=subtre[i];

           ll sum2=subtre[1]-sum1;

           ans=max(ans,sum1*sum2);

      }

      cout<<ans<<endl;

    return 0;

}