Go: package main

import "fmt"

type node struct {
	id, d, v int
	adj      []node
}

var n int
var seen []bool
var graph []node

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func dfs(v, t int) int {
	// fmt.Printf("dfs(v %d, t %d) en:\n", v, t)
	seen[v] = true
	graph[v].v = t
	tt := t
	for _, vv := range graph[v].adj {
		if !seen[vv.id] {
			tt = max(tt, dfs(vv.id, tt+1))
		}
	}
	graph[v].d = tt + 1
	// fmt.Printf("dfs(v %d, t %d) ex: d %d\n", v, t, graph[v].d)
	return graph[v].d
}

func main() {
	fmt.Scan(&n)
	graph = make([]node, n+1)
	for i := 1; i <= n; i++ {
		var u, k, v int
		fmt.Scan(&u, &k)
		graph[u].id = u
		// 頂点uはk個の隣接頂点を持っている
		for j := 0; j < k; j++ {
			fmt.Scan(&v)
			var t node
			t.id = v
			graph[u].adj = append(graph[u].adj, t)
		}
	}
	// fmt.Println("n", n, "graph", graph)
	seen = make([]bool, n+1)
	// t := dfs(1, 1)
	v, t := 1, 1
	done := false
	for !done {
		tt := dfs(v, t)
		done = true
		for i := range seen {
			if !seen[i] {
				done = false
				v = graph[i].id
				t = tt
				break
			}
		}
	}
	for i := 1; i <= n; i++ {
		fmt.Printf("%d %d %d\n", i, graph[i].v, graph[i].d)
	}
}

C++: #include <cstdio>
#include <cstring>

const int MAX = 100;
static int time = 0;
int adj[MAX][MAX];
int discover[MAX];
int finish[MAX];

void visit(int node, int n)
{
  if (finish[node] != 0)
    return;

  ++time;
  discover[node] = time;

  for (int i = 0; i < n; ++i)
  {
    if (adj[node][i] == 1 && node != i)
      visit(i, n);
  }

  ++time;
  finish[node] = time;
}

int main()
{
  std::memset(adj, 0, sizeof(adj));
  std::memset(discover, 0, sizeof(discover));
  std::memset(finish, 0, sizeof(finish));

  int n;
  scanf("%d", &n);

  int u, k, v;
  for (int i = 0; i < n; ++i)
  {
    scanf("%d%d", &u, &k);
    for (int j = 0; j < k; ++j)
    {
      scanf("%d", &v);
      adj[u - 1][v - 1] = 1;
    }
  }

  for (int i = 0; i < n; ++i)
    visit(i, n);

  for (int i = 0; i < n; ++i)
    printf("%d %d %d\n", i + 1, discover[i], finish[i]);

  return 0;
}

C++: #include"iostream"
#include"vector"
#define WHITE 0
#define GRAY 1
#define BLACK 2
using namespace std;
class vertex
{
public:
  vector<int> next;
  int first;
  int second;
  int color;
  vertex()
  {
    this->color=WHITE;
  }
};
vector<vertex> V;
int Time;
void visit(int u)
{
  V[u].color=GRAY;
  V[u].first=++Time;
  for(int v=0;v<V[u].next.size();v++)
    {
      if(V[V[u].next[v]].color==WHITE)
        {
          visit(V[u].next[v]);
        }
    }
  V[u].color=BLACK;
  V[u].second=++Time;
}
void dfs()
{
  for(int u=1;u<V.size();u++)
    {
      V[u].color=WHITE;
    }
  Time=0;
  for(int u=1;u<V.size();u++)
    {
      if(V[u].color==WHITE)
        {
          visit(u);
        }
    }
}
int main()
{
  int n;
  cin>>n;
  for(int i=0;i<=n;i++)
    {
      vertex a;
      V.push_back(a);
    }
  for(int i=1;i<=n;i++)
    {
      int num;
      cin>>num;
      int k;
      cin>>k;
      for(int j=0;j<k;j++)
        {
          int next;
          cin>>next;
          V[num].next.push_back(next);
        }
    }
  dfs();
  for(int i=1;i<=n;i++)
    {
      cout<<i<<" "<<V[i].first<<" "<<V[i].second<<endl;
    }
  return 0;
}

C++: #include <bits/stdc++.h>
#include <string>
#include <vector>
#define rep(i,n) for (int i = 0;i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int,int>;

//AOJ Depth First Search
//http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_11_B&lang=ja
using Graph = vector<vector<int>>;
vector<bool> seen;
vector<int> first_order;
vector<int> last_order;

void dfs(const Graph &G,int v,int& first_ptr){
    seen[v] = true;

    first_order[v] = first_ptr++;
    for(auto next_v: G[v]){
        if(seen[next_v]) continue;
        dfs(G,next_v,first_ptr);
    }
    last_order[v] = first_ptr++;
}
int main() {
    int v;
    cin >> v ;
    Graph G(v);

    rep(i,v){
        int u,k;
        cin >> u >> k;
        rep(j,k){
            int vi;
            cin >> vi;
            G[u-1].push_back(vi-1);
        }
    }

    seen.assign(v,false);
    first_order.resize(v);
    last_order.resize(v);
    int first_ptr = 1;
    rep(vi,v){
        if(seen[vi])continue;
        dfs(G, vi, first_ptr);
    }
    rep(i,v){
        cout << i+1 << " " << first_order[i] << " " << last_order[i] << endl;
    }
}

C++: #include <iostream>
#include <vector>
#include <stack>

using namespace std;

const int edge = 1;
const int no_edge = 0;
const int no_time = -1;
const int no_label = -1;


// return finished time
int depth_search(
  int started_label,
  int current_time,
  vector<vector<int>> matrices_graph,
  vector<int>& discovered_times,
  vector<int>& finished_times
) {
  stack<int> visited_stack;
  int vertex_num = matrices_graph.size();
  visited_stack.push(started_label);
  discovered_times[started_label -1] = ++current_time;

  while(!visited_stack.empty()) {
    int current_label = visited_stack.top();

    // find no visited vertex
    int no_visited_label = no_label;
    for(int i = 0; i < vertex_num; i++) {
      if(matrices_graph[current_label - 1][i] != edge) {
        continue;
      }
      if(discovered_times[i] != no_time) {
        continue;
      }
      no_visited_label = i + 1;
      break;
    }

    if(no_visited_label != no_label) {
      visited_stack.push(no_visited_label);
      discovered_times[no_visited_label - 1] = ++current_time;
    } else {
      int finished_label = visited_stack.top();
      visited_stack.pop();

      finished_times[finished_label - 1] = ++current_time;
    }
  }

  return current_time;
}

int main() {
  int vertex_num;
  cin >> vertex_num;
  vector<vector<int>> matrices_graph(
    vertex_num,
    vector<int>(vertex_num, 0)
  );


  // set adjacency matrices graph
  for(int i = 0; i < vertex_num; i++) {
    int vertex_label;
    int adjacency_num;
    cin >> vertex_label >> adjacency_num;

    for(int j = 0; j < adjacency_num; j++) {
      int adjacency_label;
      cin >> adjacency_label;
      matrices_graph[vertex_label -1][adjacency_label - 1] = edge;
    }
  }

  vector<int> discovered_times(vertex_num, no_time);
  vector<int> finished_times(vertex_num, no_time);

  int current_time = 0;
  for(int i = 0; i <vertex_num; i++) {
    if(discovered_times[i] == no_time) {
      int started_label = i + 1;
      current_time = depth_search(
        started_label,
        current_time,
        matrices_graph,
        discovered_times,
        finished_times
      );
    }
  }

  for(int i = 0; i < vertex_num; i++) {
    cout << i + 1 << ' ' <<  discovered_times[i] << ' ' << finished_times[i] << endl;
  }
}