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<stack>
using namespace std;

static const int N=100;
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;

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

// uに隣接するvを番号順に取得
int next(int u){
    for(int v=nt[u]; v<n; v++){ // 訪問した場所は探索しなくていいため、v+1にしている？
        nt[u] = v+1;
        if(M[u][v]) return v;
    }
    return -1;
}

// スタックを用いた深さ優先探索
void dfs_visit(int r){
    for(int i=0; i<n; i++) nt[i] = 0;

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

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

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

    // 未訪問のuを始点として深さ優先探索
    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 argc, char const *argv[])
{
    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--; // 0 origin
        for(int j=0; j<k; j++){
            cin >> v;
            v--;
            M[u][v] = 1;
        }
    }

    dfs();

    return 0;
}

C++: #define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define dump(x) cout << (x) << '\n'

using namespace std;
using Graph = vector<vector<int>>;

typedef int64_t Int;
const double pi = M_PI;

vector<bool> seen;
vector<vector<int>> timestamp; // タイムスタンプ

void dfs(const Graph &G, int v, int &time_ptr) {
    // 発見時刻
    timestamp[v][0] = time_ptr++;

    seen[v] = true; // v を探索済みにする

    // v から行ける各頂点について
    for (auto next_v : G[v]) {
        if (seen[next_v])
            continue; // 探索済みなら飛ばす

        dfs(G, next_v, time_ptr); // 再帰探索
    }

    // 完了時刻
    timestamp[v][1] = time_ptr++;
}

int main() {
    // 入力
    int N;
    cin >> N;

    // グラフの入力
    Graph G(N);
    for (int u = 0; u < N; u++) {
        int ig, k, v;
        cin >> ig >> k;
        for (; k >= 1; k--) {
            cin >> v;
            v--;
            G[u].push_back(v);
        }
    }

    // 初期化
    seen.assign(N, false);
    timestamp.assign(N, vector<int>(2, 0));
    int time_ptr = 1;
    // 探索開始
    for (int v = 0; v < N; v++) {
        if (seen[v])
            continue;

        dfs(G, v, time_ptr);
    }

    // 出力
    for (int v = 0; v < N; v++) {
        cout << v + 1 << ' ' << timestamp[v][0] << ' ' << timestamp[v][1] << endl;
    }
}

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

int t;
vector<int> d, f;
int n;
vector<vector<int> > G;

void dfs(int v) {
  if ( d[v] ) return;
  d[v] = ++t;  

  for ( int i = 0; i < n; i++ ) {
    if ( G[v][i] ) dfs(i);
  }

  f[v] = ++t;  
}

int main() {
  cin >> n;

  d = vector<int>(n, 0);
  f = vector<int>(n, 0);

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

  for ( int i = 0; i < n; i++ ) {
    for ( int j = 0; j < n; j++ ) {
      if ( j ) cout << " ";
      cout << G[i][j];
    }
    cout << endl;
  }

  for ( int i = 0; i < n; i++ ) {
    if ( !d[i] ) dfs(i);
  }

  for ( int i = 0; i < n; i++ ) {
    cout << i+1 << " " << d[i] << " " << f[i] << endl;
  }
  
  return 0;
}

C++: #include <iostream>
#include <vector>
#include <stack>
using namespace std;
static const int MAX=101;
bool Visited[MAX]; //??\?????????????¢??????????
vector<int> Adjacency[MAX];
int dTime[MAX]; int fTime[MAX]; //?¢??????°??¶??´????¢?????????¶??´
void dfs(int j,int& clock)
{

    stack<int> S;
    S.push(j);dTime[j]=++clock;
    Visited[j]=true;
    while(!S.empty())
    {
        int p=S.top(); //???????????¶??????
        if(Adjacency[p].size()==0)
        {
            S.pop();
            fTime[p]=++clock;
            continue;
        }
        int i=0;
        if(Adjacency[p].size())
          while(Visited[Adjacency[p][i]]==true)
          {
            i++;
            if(i==Adjacency[p].size()) //???????°??????????????±?????????????
            {
                S.pop();
                fTime[p]=++clock;
                break;
            }
          }
        if(i==Adjacency[p].size()) continue;
        //if founded
        S.push(Adjacency[p][i]); dTime[Adjacency[p][i]]=++clock;
        Visited[Adjacency[p][i]]=true;
    }
}
int main()
{
    int n;
    cin>>n;
    for(int i=1;i<=n;i++) Visited[i]=false;

    for(int i=1;i<=n;i++)
    {
        int p;cin>>p;
        int num;
        cin>>num;

        for(int j=0;j<num;j++)
        {
            int t;
            cin>>t;
            Adjacency[p].push_back(t);
        }
    }
    int clock=0;
    for(int i=1;i<=n;i++)  //???????????????????????°DFS?£?????????????
    {
        if(Visited[i]==false) dfs(i,clock);
    }
    for(int i=1;i<=n;i++)
        cout<<i<<' '<<dTime[i]<<' '<<fTime[i]<<endl;
}