洛谷P1352

#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

ll n,a[(int)1e4+9],dp[(int)1e4+9][2];
vi g[(int)1e4+9];
bitset<(int)1e4+9> ez;

void dfs(int u){
    dp[u][0]=0,dp[u][1]=a[u];
    for(auto it:g[u]){
        dfs(it);
        dp[u][0]+=max(dp[it][1],dp[it][0]),dp[u][1]+=dp[it][0];
    }
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>n;
    f(i,1,n)cin>>a[i];
    for(int i=2,x,y;i<=n;++i){
        cin>>x>>y;
        g[y].push_back(x);
        ez[x]=1;
    }
    f(i,1,n){
        if(!ez[i]){
            dfs(i);
            cout<<max(dp[i][0],dp[i][1]);
            return 0;
        }
    }
    return 0;
}