//这里填你的代码^^
#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
const int N = 1e4 + 10;
int h[N], e[N], ne[N], w[N], idx;
bool father[N];
int f[N][2];
inline void add(int a, int b)
{
    e[idx] = b, ne[idx] = h[a], h[a] = idx ++;
}
inline void dfs(int u)
{
    f[u][1] = w[u];
    for (int i = h[u]; ~i; i = ne[i])
    {
        int j = e[i];
        dfs(j);
        int cnt = f[j][0] > f[j][1] ? f[j][0] : f[j][1];
        f[u][0] += cnt;
        f[u][1] += f[j][0];
    }
}
inline void solve()
{
    int n;
    cin >> n;
    memset(h, -1, sizeof h);
    for (int i = 1; i <= n; i ++ ) cin >> w[i];
    for (int i = 1; i < n; i ++ )
    {
        int l, k;
        cin >> l >> k;
        father[l] = true;
        add(k, l);
    }
    int root = 1;
    while (father[root]) root ++;
    dfs(root);
    int cnt = f[root][0] > f[root][1] ? f[root][0] : f[root][1];
    cout << cnt << endl;
}
int main()
{
    cin.tie(nullptr) -> sync_with_stdio(0);
    solve();
    return 0;
}

作者：navystar
链接：https://www.acwing.com/solution/content/189943/
来源：AcWing
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//注意代码要放在两组三个点之间，才可以正确显示代码高亮哦~