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<stdio.h>
#define Gray 0
#define White 1
#define Black 2
int time;
int d[101],f[101],color[101],Adj[101][101];  
int n;

void DFS_Visit(int u){
  int i;  
  color[u]=Gray;
  d[u]=++time;
  for(i=1;i<=n;i++){
    if(color[i]==White && Adj[u][i]==1) DFS_Visit(i);
  }
  color[u]=Black;
  f[u]=++time;
}

void DFS(){
  int i;
  for(i=1;i<=n;i++){
    color[i]=White;
  }
  time=0;
  for(i=1;i<=n;i++){
    if(color[i]==White) DFS_Visit(i);
}
}

main(){
  
  int k,i,j,t,g;

  scanf("%d",&n);
    for(i=0;i<=n;i++){
      for(j=0;j<=n;j++){
	Adj[i][j]=0;
      }
    } 
    
    for(i=1;i<=n;i++){
      scanf("%d",&g);    
      scanf("%d",&k);
      for(j=1;j<=k;j++){
	scanf("%d",&t);
	Adj[g][t]=1;   
      }
    } DFS();
    
    for(i=1;i<=n;i++){
   
      printf("%d %d %d\n",i,d[i],f[i]);
    }
    return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using Graph = vector<vector<int>>;

vector<bool> seen;
vector<int> first_order; // 行きがけ順
vector<int> last_order; // 帰りがけ順
void dfs(const vector<vector<int>> &G,int v,int& ptr){
  first_order[v] = ptr++;

  // vを訪問済みにする
  seen[v] = true;

  // vから行ける各頂点next_vについて
  for(auto next_v:G[v]){
    if(seen[next_v]) continue;
    dfs(G,next_v,ptr);
  }

  last_order[v] = ptr++;
}

int main(){
  //頂点数
  int n;
  cin >> n;

  Graph G(n+1);
  //頂点番号、隣接頂点数、隣接頂点番号
  for(int i=1;i<=n;i++){
    int u,k;
    cin >> u >> k;
    for(int j=0;j<k;j++){
      int v;
      cin >> v;
      G[u].push_back(v);
    }
  }

  seen.assign(n+1,false);
  first_order.resize(n+1);
  last_order.resize(n+1);
  int ptr = 1;
  for(int i=1;i<=n;i++){
    if(seen[i]) continue;
    dfs(G,i,ptr);
  }

  // 各頂点vの行きがけ順、帰りがけ順を出力
  for(int v = 1;v<=n;v++){
    cout << v << " " << first_order[v] << " " << last_order[v] << endl;
  }
}

C++: #include <iostream>
#include <stack>
using namespace std;
static const int N = 100;
static const int WHITE = 0;
static const int GREY = 1;
static const int BLACK = 2;

int n, M[N][N];
int color[N], d[N], f[N], tt;
int nt[N];


int next(int u) {
	for (int v = nt[u]; v < n; v++) {
		nt[u] = v + 1;
		if (M[u][v]) return v;
	}
	return -1;
}


void dfs_visit(int r) {
	for (int i = 0; i < n; i++) nt[i] = 0;

	stack<int> S;
	S.push(r);
	color[r] = GREY;
	d[r] = ++tt;

	while (!S.empty()) {
		int u = S.top();
		int v = next(u);
		if (v != -1) {
			if (color[v] == WHITE) {
				color[v] = GREY;
				d[v] = ++tt;
				S.push(v);
			}
		}
		else {
			S.pop();
			color[u] = BLACK;
			f[u] = ++tt;
		}
	}
}


void dfs() {
	for (int i = 0; i < n; i++) {
		color[i] = WHITE;
		nt[i] = 0;
	}
	tt = 0;

	for (int u = 0; u < n; u++) {
		if (color[u] == WHITE) dfs_visit(u);
	}
	for (int i = 0; i < n; i++) {
		cout << i + 1 << " " << d[i] << " " << f[i] << endl;
	}
}


int main() {
	int u, k, v;

	cin >> n;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) M[i][j] = 0;
	}

	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		u--;
		for (int j = 0; j < k; j++) {
			cin >> v;
			v--;
			M[u][v] = 1;
		}
	}

	dfs();

	return 0;
}