DP en árboles - Resolver para todas las raíces

#include <bits/stdc++.h>
using namespace std;
 
vector<int> graph[200001];
int fir[200001], sec[200001], ans[200001];
 
void dfs1(int node = 1, int parent = 0) {
	for (int i : graph[node])
		if (i != parent) {
			dfs1(i, node);
			if (fir[i] + 1 > fir[node]) {
				sec[node] = fir[node];
				fir[node] = fir[i] + 1;
			} else if (fir[i] + 1 > sec[node]) {
				sec[node] = fir[i] + 1;
			}
		}
}
 
void dfs2(int node = 1, int parent = 0, int to_p = 0) {
	ans[node] = max(to_p, fir[node]);
	for (int i : graph[node])
		if (i != parent) {
			if (fir[i] + 1 == fir[node]) dfs2(i, node, max(to_p, sec[node]) + 1);
			else dfs2(i, node, ans[node] + 1);
		}
}
 
int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n;
	cin >> n;
	for (int i = 1; i < n; i++) {
		int u, v;
		cin >> u >> v;
		graph[u].push_back(v);
		graph[v].push_back(u);
	}
	dfs1();
	dfs2();
	for (int i = 1; i <= n; i++) cout << ans[i] << ' ';
	return 0;
}

import java.io.*;
import java.util.*;
 
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());
		g = new ArrayList[N + 1];
		maxl1 = new Pair[N + 1];
		maxl2 = new Pair[N + 1];
		for (int i = 0; i <= N; i++) {
			g[i] = new ArrayList<Integer>();
			maxl1[i] = new Pair(0, 0);
			maxl2[i] = new Pair(0, 0);
		}
 
		for (int i = 1; i < N; i++) {
			StringTokenizer st = new StringTokenizer(br.readLine());
			int a = Integer.parseInt(st.nextToken());
			int b = Integer.parseInt(st.nextToken());
			g[a].add(b);
			g[b].add(a);
		}
		dfs1(1, 0);
		dfs2(1, 0);
		for (int i = 1; i <= N; i++) { System.out.print(maxl1[i].f + " "); }
	}
	public static int dfs1(int i, int p) {
		int ret = 0;
		for (int next : g[i]) {
			if (next != p) {
				int c = dfs1(next, i);
				ret = Math.max(ret, c + 1);
				if (c + 1 > maxl1[i].f) {
					maxl2[i] = maxl1[i];
					maxl1[i] = new Pair(c + 1, next);
 
				} else if (c + 1 > maxl2[i].f) {
					maxl2[i] = new Pair(c + 1, next);
				}
			}
		}
		return ret;
	}
	public static void dfs2(int i, int p) {
		if (p != 0) {
			if (maxl1[p].s == i) {
				if (maxl2[p].f + 1 > maxl1[i].f) {
					maxl2[i] = maxl1[i];
					maxl1[i] = new Pair(maxl2[p].f + 1, p);
 
				} else if (maxl2[p].f + 1 > maxl2[i].f) {
					maxl2[i] = new Pair(maxl2[p].f + 1, p);
				}
			} else {
				if (maxl1[p].f + 1 > maxl1[i].f) {
					maxl2[i] = maxl1[i];
					maxl1[i] = new Pair(maxl1[p].f + 1, p);
				} else if (maxl1[p].f + 1 > maxl2[i].f) {
					maxl2[i] = new Pair(maxl1[p].f + 1, p);
				}
			}
		}
		for (int next : g[i]) {
			if (next != p) dfs2(next, i);
		}
	}
	static class Pair {
		public int f, s;
		public Pair(int f, int s) {
			this.f = f;
			this.s = s;
		}
	}
}