获取最多食物-树形dp

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int n;
vector<vector<int>> nodes;
vector<int> dp;

int dfs(int i)
{
    if(dp[i] != INT_MIN) return dp[i];
    if(nodes[i][0] == -1) return nodes[i][1];
    dp[i] = max(nodes[i][1], nodes[i][1] + dfs(nodes[i][0]));
    return dp[i];
}

int main()
{
    cin >> n;
    nodes = vector<vector<int>> (n, vector<int>(2));
    for(int i = 0; i < n; i ++)
    {
        int id, pid, val;
        cin >> id >> pid >> val;
        nodes[id][0] = pid;
        nodes[id][1] = val;
    }

    dp = vector<int> (n, INT_MIN);
    for(int i = 0; i < n; i ++) dfs(i);

    cout << *max_element(dp.begin(), dp.end()) << endl;
    return 0;
}