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+1)
	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>
//#define int long long

using namespace std;
using LL = long long;
using P = pair<int, int>;

#define FOR(i, a, n) for(int i = (int)(a); i < (int)(n); ++i)
#define REP(i, n) FOR(i, 0, n)

#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()

const int INF = (int)1e9;
const LL INFL = (LL)1e19;
const int MOD = 1e9 + 7;

using Graph = vector<vector<int>>;

int dfs(Graph &graph, vector<int> &d, vector<int> &f, int cur, int time)
{
    if(d[cur] > 0) return time;
    d[cur] = time;
    time++;
    for(int child : graph[cur])
    {
        time = dfs(graph, d, f, child, time);
    }
    f[cur] = time;
    time++;
    return time;
}

signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int n;
    cin >> n;
    Graph graph(n);
    REP(i, n) 
    {
        int u, k;
        cin >> u >> k;
        REP(j, k) 
        {
            int v;
            cin >> v;
            graph[u-1].push_back(v-1);
        }
    }

    vector<int> d(n, 0), f(n, 0);
    int time = 1;
    REP(i, n)
    {
        if(d[i] > 0) continue;
        time = dfs(graph, d, f, i, time);
    }

    REP(i, n)
    {
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
}

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

int G[101][102];
int found[101];
int comp[101];   // complete.
int t;  // time.

typedef struct box{ int val; box* next; } box_t;  // stack.

box_t* init()
{
    box_t* head = new box_t;
    head->val = -1;
    head->next = NULL;
    return head;
}

bool isEmpty(box_t* head){ return (head->next == NULL ? true : false); }

box_t* push(box_t* head, int data)
{
    box_t* box = new box_t;
    box->val = data;
    box->next = head->next;
    head->next = box;
    return box;
}

int pop(box_t* head)
{
    if(isEmpty(head)){ return -1; }
    box_t* box = head->next;
    int val;
    head->next = box->next;
    val = box->val;
    delete box;
    return val;
}

int front(box_t* head)
{
    int val;
    if(isEmpty(head)){ return -1; }
    val = head->next->val;
    return val;
}

box_t* stack = init();

void search_loop(int i)
{
    int j, k;
    while(1){
        if(found[i] == 0){
            t++; found[i] = t;
            push(stack, i);
        }
        for(k = G[i][0]; G[i][k] != 0 && found[G[i][k]] != 0; k++);
        if(G[i][k] == 0){
            if(isEmpty(stack)){ return; }
            else{
                j = pop(stack);
                t++; comp[j] = t;
                i = front(stack);
            }
        }else{
            G[i][0] = k + 1;
            i = G[i][k];
        }
    };
    return;
}

int main()
{
    int n, i, j, a, b, e;
    cin >> n;
    for(i = 1; i <= n; i++){
        G[i][0] = 1;
        for(j = 1; j <= n + 1; j++){ G[i][j] = 0; } }

    for(i = 1; i <= n; i++){
        cin >> a >> e;
        for(j = 1; j <= e; j++){
            cin >> b; G[a][j] = b; } }  // adjacent representation.

    for(i = 1; i <= n; i++){ found[i] = 0; comp[i] = 0; }
    t = 0;
    while(1){
        for(i = 1; i <= n; i++){
            if(found[i] == 0) break;
        }
        if(i > n) break;
        search_loop(i);
    };

    for(i = 1; i <= n; i++){
        cout << i << " " << found[i] << " " << comp[i] << endl;
    }
    return 0;
}

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

struct Graph{
	
	vector<char> seen;
	vector<vector<int>> e;
	vector<int> time1,time2; 
	Graph(int n) : seen(n),e(n),time1(n),time2(n){}
	
	void dfs(int v, int &t){
		t++;
		time1.at(v) = t;
		seen.at(v) = 1;
		for(auto nv:e.at(v)) {
			if(seen.at(nv)==1) continue;
			dfs(nv,t);
		}
		t++;
		time2.at(v) = t;
		return;
	}
	
};

int main() {
	
	int n;
	cin >> n;
	Graph graph(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;
			v--;
			graph.e.at(i).push_back(v);
		}
	}
	
	int t={};
	for(int i=0; i<n; i++){
		if(graph.seen.at(i)!=1) graph.dfs(i,t);
	}
	
	for(int i=0; i<n; i++){
		cout << i+1 << ' ' << graph.time1.at(i) << ' ' << graph.time2.at(i) << endl;
	}
	
	
}

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

#define MAX 101

using namespace std;

int visited[MAX],d[MAX],f[MAX],called[MAX];
int tt=0;
vector<int> G[MAX];
stack<int> S;

int getNext(int u){
  if(called[u]>=G[u].size()) return -1;
  else{
    int x=G[u][called[u]];
    called[u]++;
    return x;
  }
}


void dfs(int u){
  S.push(u);
  visited[u]=1;
  d[u]=++tt;
  while(S.empty()==false){
    int x=S.top();
    int v=getNext(x);
    if(v!=-1){
      if(visited[v]==0){
        visited[v]=1;
        d[v]=++tt;
        S.push(v);
      }
    }else{
      S.pop();
      visited[x]=1;
      f[x]=++tt;
    }
  }
}

int main(){
  int n; cin >> n;
  for(int i=1;i<=n;i++){
    visited[i]=0;
    called[i]=0;
  }
  for(int i=0;i<n;i++){
    int u,k; cin >> u >> k;
    for(int i=0;i<k;i++){
      int v; cin >> v;
      G[u].push_back(v);
    }
  }
  for(int i=1;i<=n;i++){
    if(visited[i]==0){
      dfs(i);
    }
  }
  for(int i=1;i<=n;i++){
    cout << i << " " << d[i] << " " << f[i] << endl;
  }
}