来源于yxc视频讲解

#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;

const int N = 110;

int n, m;
int h[N], e[N], ne[N], idx;
int v[N], w[N];
int f[N][N];

void add(int x, int y) {
    e[idx] = y, ne[idx] = h[x], h[x] = idx++;
}

void dfs(int x) {
    for (int i = h[x]; i != -1; i = ne[i]) {
        int y = e[i];
        dfs(y);
        for (int j = m - v[x]; j >= 0; j--) {
            for (int k = 0; k <= j; k++) {
                f[x][j] = max(f[x][j], f[x][j - k] + f[y][k]);
            }
        }
    }
    for (int i = m; i >= v[x]; i--) {
        f[x][i] = f[x][i - v[x]] + w[x];
    }
    for (int i = 0; i < v[x]; i++) {
        f[x][i] = 0;
    }
}

int main() {
    memset(h, -1, sizeof h);
    cin >> n >> m;
    int root;
    for (int i = 1; i <= n; i++) {
        int p;
        cin >> v[i] >> w[i] >> p;
        if (p == -1) {
            root = i;
        } else {
            add(p, i);
        }
    }
    dfs(root);
    cout << f[root][m] << endl;
    return 0;
}