Recursive sum of each sub tree

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
#define f(i,a,n)  for(int i = a; i < n; i++)
#define pb(x) push_back(x)
vector < vector < int > > v(100034);
int vis[100123]  ={0};
int bn_gya_bsdka[1000000];
vector < int > s;
int arr[100012] = {0};int res = 0,ans = 1000000000;
int dfs(int top){
    vis[top] = 1;int sum = 0;
   // if(v[top].size() == 1){arr[top] = bn_gya_bsdka[top];return bn_gya_bsdka[top];}
    for(auto i : v[top]){
        if(!vis[i]){
        sum += dfs(i);;
            //dfs(i);
        }
    }
   // cout << top << ' ' << sum << '\n';
    if(top != 1)
    ans = min(ans,abs(res-2*(sum + bn_gya_bsdka[top])));
    arr[top] = sum + bn_gya_bsdka[top];
    return sum + bn_gya_bsdka[top];
}
void dfs1(int i){
    vis[i]  = 1;
    cout << i << ' ';
    for(auto j : v[i]){
        if(!vis[j])dfs1(j);
    }
}
int main(){
	int n;
	cin >> n;
	//vector < pair < int, int > > v;
    f(i,0,n)cin >> bn_gya_bsdka[i+1],res += bn_gya_bsdka[i+1];
    vector < pair < int, int > > p;
	int l, r;
	f(i,0,n){
		cin >> l >> r;
      //  p.push_back({l,r});
		v[l].pb(r),v[r].pb(l);
	}
  int y = dfs(1);
    cout << ans;
	return 0;
}