Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveDfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

func nextInt(sc *bufio.Scanner) (int, error) {
	return strconv.Atoi(nextText(sc))
}

C++: #include <iostream>
#include <vector>
using namespace std;

vector<int> G[100];
pair<int, int> T[100];
const int Inf = 10000*100000+100;
int timer = 1;

int main() {
  void dfs(int cur);
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)
  {
    int u, k;
    cin >> u >> k;
    for (int l = 0; l < k; l++) {
      int v;
      cin >> v;
      G[i].push_back(v - 1);
    }
    T[i] = make_pair(Inf, Inf);
  }
  for (int i = 0; i < n; i++) {
    if (T[i].first == Inf) {
      dfs(i);
    }
  }
  for (int i = 0; i < n; i++)
  {
    cout << i + 1 << " " << T[i].first << " " << T[i].second << endl;
  }
}

void dfs(int cur) { // cur を訪問
  // cur の訪問時刻を記録
  T[cur].first = timer;
  timer += 1;
  // 動作確認用表示
  for (int dst : G[cur]) { // 全ての節点 dst について
    if (T[dst].first == Inf)
    { // cur から dst に辺があり，dst を未訪問なら
      dfs(dst);
    }
  }
  T[cur].second = timer;
  timer += 1;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int n;
bool G[110][110];
int d[110], f[110], timer;
bool seen[110];

void dfs(int now){
    d[now] = timer;

    seen[now] = true;

    for(int to=1; to<=n; ++to){
        if(G[now][to] == true && seen[to] == false){
            ++timer;
            dfs(to);
        }
    }

    ++timer;
    f[now] = timer;

}

int main(){
    cin >> n;
    for(int i=0; i<n; ++i){
        int u,k; cin >> u >> k;
        for(int j=0; j<k; ++j){
            int v; cin >> v;
            G[u][v] = true;
        }
    }

    timer = 0;
    for(int i=1; i<=n; ++i){
        if(seen[i] == false){
            ++timer;
            dfs(i);
        }
    }

    for(int i=1; i<=n; ++i){
        printf("%d %d %d\n", i, d[i], f[i]);
    }
}

C++: #include<iostream>
#include<vector>
using namespace std;

int t=1;
int n;
int d[101],f[101];
int v[101];
vector<int> edges[101];

void dfs(int cur)
{
    if(d[cur]==-1)
    {
        d[cur]=t;
        v[cur]=1;
        t+=1;
    }
    int dst;
    for(dst=1;dst<=n;dst++)
    {
        int flag=0;
        for(int i=0;i<edges[cur].size();i++)
        {
            if(edges[cur][i]==dst)
				{
					flag=1;
					break;
				}
        }
        if(v[dst]==-1&&flag)
		  dfs(dst);
    }
    if(f[cur]==-1)
    {
        f[cur]=t;
        t+=1;
    }
}

int main()
{
	cin >> n;
	for(int i=0;i<n;i++)
	{
		int u,k,y;
		cin >> u >> k;
		for(int j=0;j<k;j++)
        {
            cin >> y;
            edges[u].push_back(y);
        }
	}
	for(int i=1;i<=n;i++)
	{
        d[i]=-1;
        f[i]=-1;
        v[i]=-1;
    }
	for(int dst=1;dst<=n;dst++)
        dfs(dst);
	for(int i=1;i<=n;i++)
	   cout << i << ' ' << d[i] <<  ' ' <<  f[i] <<  endl;
}

C++: #include <bits/stdc++.h> 

#define int long long
#define double long double

#define REP(i, b) for(int i = 0; i < (b); i++)
#define REPS(i, b) for(int i = 1; i <= (b); i++)
#define ALL(v) (v).begin(), (v).end()

#define fi first
#define se second
#define pb push_back
#define mp make_pair

using namespace std;

using pi = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vs = vector<string>;
using vb = vector<bool>;
using vpi = vector<pi>;
using vvi = vector<vi>;
using vvb = vector<vb>;

const int INF = 1e16;
const int MOD = 1e9+7;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

int n;
vi d, f;
vvi G;
int t = 0;

void dfs(int n)
{
    t++;
    d[n] = t;
    for(int i : G[n]) if(d[i] == 0) dfs(i);
    t++;
    f[n] = t;
}

signed main()
{
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    cin >> n;
    G.resize(n+1);
    d.resize(n+1, 0);
    f.resize(n+1, 0);
    REP(i, n)
    {
        int u, k; cin >> u >> k;
        REP(j, k)
        {
            int v; cin >> v;
            G[u].pb(v);
        }
    }

    REPS(i, n)
    {
        if(d[i] == 0) dfs(i);
    }

    REPS(i, n) cout << i << " " << d[i] << " " << f[i] << endl;
}

C++: #include <iostream>
#include <vector>
using namespace std;

class vertex{
public:
  vector<vertex*> to;
  bool visited;
  int num;
  int visit_time;
  int leave_time;
  vertex(){
    visited=false;
  }
  void dfs(){
    visited=true;
    visit_time=time();
    for(int i=0; i<to.size(); i++){
      if(!to[i]->visited) to[i]->dfs();
    }
    leave_time=time();
  }

  void print(){
    cout << num << " " << visit_time << " " << leave_time << endl;
  }

private:
  static int time(){
    static int ti=0;
    ti++;
    return ti;
  }
};

int main(){
  int n; cin >> n;
  vertex graph[n+1];

  int v, k, to;
  for(int i=0; i<n; i++){
    cin >> v >> k;
    graph[v].num = v;
    for(int j=0; j<k; j++){
      cin >> to;
      graph[v].to.push_back(&graph[to]);
    }
  }


  for(int v=1; v<=n; v++){
    if(!graph[v].visited) graph[v].dfs();
  }

  for(int v=1; v<=n; v++){
    graph[v].print();
  }
  
  return 0;
}