错误数据#2，本地编译能过

代码：

#include <iostream>
using namespace std;
const int N = 6010;
int n;
int w[N], f[N][2 /*0表示不选该节点，1表示选该节点*/];
int son[N /*爹的编号*/][N /*第几个儿子*/] /*值是儿子的编号*/;
int NumberOfSons[N];
int fa[N /*儿子的编号*/] /*爹的编号*/;
void dfs_dp(int node)//dfs遍历，回溯dp
{
    f[node][1] = w[node];
    for (int i = 1; i <= NumberOfSons[node]; i++)
    {
        int SonNode = son[node][i];
        dfs_dp(SonNode);
        f[node][0] += max(f[SonNode][0], f[SonNode][1]);
        f[node][1] += f[SonNode][0];
    }
    return;
}
int main()
{
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> w[i];
    for (int i = 1; i < n; i++)
    {
        int x, y;
        cin >> x >> y;
        NumberOfSons[y]++;
        son[y][NumberOfSons[y]] = x;
        fa[x] = y;
    }
    // 寻找根节点
    int root = 1;
    while (fa[root])
        root = fa[root];
    dfs_dp(root);
    cout << max(f[root][0], f[root][1]);
    return 0;
}