(Optional) DP on Trees - Solving For All Roots

C++

#include <bits/stdc++.h>
using namespace std;

vector<int> graph[200001];
pair<int, int> best[200001];
int sec[200001], ans[200001];

void dfs1(int node = 1, int parent = 0) {
    for (int i : graph[node]) if (i != parent) {
        dfs1(i, node);

Java

import java.util.*;
import java.io.*;

public class Main {
    public static ArrayList <Integer> g[];
    public static Pair maxl1[];
    public static Pair maxl2[];
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(br.readLine());