Go: package main

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

/***************************************************************
stackによる深さ優先探索を実装する。
***************************************************************/

const (
	N     = 100
	WHITE = 0
	GRAY  = 1
	BLACK = 2
)

var (
	n            int
	Adj          [N][N]int
	statusColor  [N]int
	discoverTime [N]int
	finishTime   [N]int
	clock        int
	nt           [N]int
)

/***************************************************************
Stackの定義:
- field
	container: ノードの格納されたスライス
	sp: スタックポインタ
- method
	size(): スタックに積まれているノードの個数を返す
	top(): スタックの一番上に積まれているノードを返す
	isEmpty(): スタックが空かどうかを返す
	pop(): スタックの要素をポップし削除する
	push(): スタックに要素を積む
***************************************************************/

type Stack struct {
	container []int
	sp        int
}

func (s *Stack) size() int {
	return len(s.container)
}

func (s *Stack) top() int {
	return s.container[s.sp]
}

func (s *Stack) isEmpty() bool {
	return s.sp == 0
}

func (s *Stack) pop() int {
	_pop := func() {
		s.container = s.container[:len(s.container)-1]
	}
	defer _pop()
	if s.isEmpty() {
		panic("There is no elements in stack!")
	}
	s.sp--
	return s.container[s.sp]
}

func (s *Stack) push(n int) {
	s.sp++
	s.container[s.sp] = n
}

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

func _DFS(target int) {
	for i := 0; i < n; i++ {
		nt[i] = 0
	}
	stack := new(Stack)
	stack.container = make([]int, N)
	stack.push(target)
	statusColor[target] = GRAY
	clock++
	discoverTime[target] = clock
	for !stack.isEmpty() {
		u := stack.top()
		v := next(u)
		if v != -1 {
			if statusColor[v] == WHITE {
				statusColor[v] = GRAY
				clock++
				discoverTime[v] = clock
				stack.push(v)
			}
		} else {
			stack.pop()
			statusColor[u] = BLACK
			clock++
			finishTime[u] = clock
		}
	}
}

func DFS() {
	for i := 0; i < n; i++ {
		statusColor[i] = WHITE
		nt[i] = 0
	}
	clock = 0
	for i := 0; i < n; i++ {
		if statusColor[i] == WHITE {
			_DFS(i)
		}
	}
	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", i+1, discoverTime[i], finishTime[i])
	}
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	scanner.Scan()
	n, _ = strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		for j := 0; j < n; j++ {
			Adj[i][j] = 0
		}
	}
	for i := 0; i < n; i++ {
		scanner.Scan()
		u, _ := strconv.Atoi(scanner.Text())
		scanner.Scan()
		k, _ := strconv.Atoi(scanner.Text())
		u--
		for j := 0; j < k; j++ {
			scanner.Scan()
			v, _ := strconv.Atoi(scanner.Text())
			v--
			Adj[u][v] = 1
		}
	}

	DFS()
}

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


vector<bool> seen;
vector<int> first_order;
vector<int> last_order;

void dfs(const vector<vector<int>> &G, int v, int& time){
	first_order[v] = time++;
	seen[v] = true;
	for(auto next_v:G[v]){
		if(seen[next_v]) continue;
		dfs(G, next_v, time);
	}
	last_order[v] = time++;
}

int main()
{
	int n;
	cin>>n;
	vector<vector<int>> G(n+1);
	for(int i=1;i<n+1;i++){
		int a, b, c;
		cin>>a>>b;
		for(int j=0;j<b;j++){
			cin>>c;
			G[a].push_back(c);
		}
	}
	seen.assign(n+1, false);
	first_order.resize(n+1);
	last_order.resize(n+1);
	int time = 1;
	for(int i=1;i<n+1;i++){
		if(seen[i]) continue;
		dfs(G, i, time);
	}
	
	for(int i=1;i<n+1;i++){
		cout<< i << " " << first_order[i] << " " << last_order[i] << endl;
	}
}

C++: #include <iostream>
#include <queue>
#include <vector>
#include <algorithm>

using namespace std;

int curTime = 1;
void dfs(int cur, const vector<vector<bool> >& a, vector<int>& d, vector<int>& f, vector<bool>& visited){
  visited[cur] = true;
  d[cur] = curTime;
  curTime++;
  // cerr << "visiting [" << cur << "], time = " << curTime << endl;

  for(int dst = 1; dst <= a.size(); dst++){
    if(a[cur][dst] && !visited[dst]) {// cur????????¶??????????????????????????????
      dfs(dst, a, d, f, visited);
    }
  }
  f[cur] = curTime;
  curTime++;
  return;
}

int main(){
  int n;
  cin >> n;
  vector<vector<bool> > a(n+1, vector<bool>(n+1, false));
  for(int i = 1; i <= n; i++){
    int u;
    cin >> u;
    int k;
    cin >> k;
    for(int j = 0; j < k; j++){
      int v;
      cin >> v;
      a[i][v] = true;
    }
  }

  vector<bool> visited(n+1, false);
  vector<int> d(n+1), f(n+1);

  dfs(1, a, d, f, visited);

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

C++: #include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
vector<int> F[102];
int start[102]={0},END[102]={0};
bool visit[102]={0};
int Count=0;
void dfs(int now){
	start[now]=Count++;
	visit[now]=true;
	int len=F[now].size();
	for(int i=0;i<len;i++){
		int p=F[now][i];
		if(visit[p]==false){
		     dfs(p);
		}
	}
	END[now]=Count++;
}
int main() {
	int n;
    cin>>n;
    for (int i=0;i<n;i++) {
            int s,num;
            cin>>s>>num;
            s--;
            for (int j=0;j<num;j++) {
                int e;
                cin>>e;
                e--;
				if(e!=s){
					F[s].push_back(e);
				}
            }
        }
        for (int i=0;i<n;i++){
			if(visit[i]==false){
				dfs(i);
			}
        }      
        for (int i = 0; i < n;i++) {
            cout<<i+1<<" "<<start[i]+1<<" "<<END[i]+1<<endl;
        }
    return 0;
}

C++: #include<iostream>
#include<vector>
using namespace std;
vector<vector<int>> G(100);
vector<pair<int,int>> D(100);
bool visited[100];
int elapse = 1;
void dfs(int x){
    if(visited[x]) return;
    visited[x] = true;
    D[x].first = elapse;
    elapse++;
    for(auto &a:G[x]) dfs(a);
    D[x].second = elapse;
    elapse++;
}
int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N;
    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-1].push_back(--v);
        }
    }
    for(int i=0;i<N;++i) dfs(i);
    for(int i=0;i<N;++i) cout<<i+1<<' '<<D[i].first<<' '<<D[i].second<<endl;
}

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


#define INF 1000000000000
int n;
vector<int>d(101);
vector<int>f(101);
vector<vector<int>>g(101,vector<int>(0));
int tim=1;
void dfs(int x){
      if(!d[x]){d[x]=tim;tim++;}
      if(!g[x].size()&& !f[x]){f[x]=tim; tim++;}
  rep(i,g[x].size()){
    if(!d[g[x][i]])dfs(g[x][i]);
    if(i==g[x].size()-1&& !f[x]){f[x]=tim;tim++;}
  }
}
int restart=0;
bool owari(vector<int>l){
  rep(i,n){
    if(l[i+1]==0){return false;}
  }
  return true;
}
signed main() {

   cin>>n;
   rep(i,n){
     int t,m;cin>>t>>m;
     rep(j,m){int k; cin>>k; if(k!=i+1){g[i+1].push_back(k);}}
   }

   while(!owari(d)){
     int restart=0;
     rep(i,n){if(d[i+1]==0){restart=i+1;break;}}
     dfs(restart);
   }
   rep(i,n){
     cout<<i+1<<' '<<d[i+1]<<' '<<f[i+1]<<endl;
   }
}