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>
using namespace std;

void dfs(int& time,
    int start,
    const vector<vector<int>>& graph,
    vector<int>& arraialTimes,
    vector<int>& leftTimes,
    vector<bool>& checkList)
{
    stack<int> stack;
    stack.push(start);
    checkList[start] = true;
    arraialTimes[start] = ++time;
 
    while (!stack.empty())
    {
        int v = stack.top();
        int vSize = 0;
        for (int w : graph[v]) {
            if (!checkList[w]) {
                ++vSize;
                stack.push(w);
                checkList[w] = true;
                arraialTimes[w] = ++time;
                break;
            }
        }
        if (vSize == 0) {
            stack.pop();
            leftTimes[v] = ++time;
        }
    }
}

int main() {
    int n;
    cin >> n;
    vector<vector<int>> graph(n);
    vector<bool> checkList(n);
    vector<int> arrivalTimes(n);
    vector<int> leftTimes(n);


    graph.reserve(n);
    for (auto& g : graph) {
        int id;
        cin >> id;
        int size;
        cin >> size;
        for (int j = 0; j < size; ++j) {
            int k;
            cin >> k;
            g.push_back(k-1);
        }
    }
    int time = 0;
    for (int i = 0; i < n; ++i) {
        if (!checkList[i]) {
            dfs(time, i, graph, arrivalTimes, leftTimes, checkList);
        }
    }
    for (int i = 0; i < n; ++i) {
        cout << i+ 1 << " " << arrivalTimes[i] << " " << leftTimes[i]<< endl;
    }

}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <stack>
using namespace std;
const int maxx = 110;
int n, m[maxx][maxx];
int u, num, v;
int d[maxx], f[maxx];
int flag[maxx];
int nowtime = 1;

void dfs(int u) {

    // 入栈时间
    flag[u] = 1;
    d[u] = nowtime++;
    for (int i = 1; i <= n; i++) {
        if (flag[i] == 0 && m[u][i] == 1) {
            dfs(i);
        }
    }
    //出栈时间
    f[u] = nowtime++;
}

int main()
{

    scanf("%d", &n);
    memset(m, 0, sizeof(m));
    memset(f, 0, sizeof(f));
    for (int i = 1; i <= n; i++) {
        scanf("%d %d", &u, &num);
        for (int j = 1; j <= num; j++) {
            scanf("%d", &v);
            m[u][v] = 1;
        }
    }
    for (int i = 1; i <= n; i++) {
        if(flag[i] == 0)
            dfs(i);
    }
    for (int i = 1; i <= n; i++) {
        printf("%d %d %d\n", i, d[i], f[i]);
    }
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int n,lis[111][111]={},d[111]={},f[111],t=1;

void dfs(int now){
  d[now]=t++;
  for(int i=1;i<=n;i++)
    if(lis[now][i]&&d[i]==0)dfs(i);
  f[now]=t++;
}

int main(){
  cin>>n;
  for(int c=0;c<n;c++){
    int u,k,v;
    cin>>u>>k;
    for(int i=0;i<k;i++){
      cin>>v;
      lis[u][v]=1;
    }
  }
  for(int i=1;i<=n;i++)if(d[i]==0)dfs(i);
  for(int i=1;i<=n;i++)cout<<i<<" "<<d[i]<<" "<<f[i]<<endl;  
  
  return 0;
}

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

struct node {
	int num;
	std::vector<int> child;
};

int recurcive(node nodes[],int d[100], int f[100], int n, int count) {
	d[n] = count++;
	for (size_t i = 0; i < nodes[n].child.size(); i++) {
		if (d[nodes[n].child[i]] == 0) {
			count = recurcive(nodes, d, f, nodes[n].child[i], count);
		} else {
			nodes[n].child.erase(std::find(nodes[n].child.begin(), nodes[n].child.end(), nodes[n].child[i]));
		}
	}
	f[n] = count++;

	return count;
}

int main() {
	int node_num;
	node nodes[100];
	std::cin >> node_num;

	for (int i = 0; i < node_num; i++) {
		int n, num;
		std::cin >> n >> num;
		for (int j = 0; j < num; j++) {
			int val;
			std::cin >> val;
			nodes[n - 1].child.push_back(val - 1);
		}
	}

	std::stack<int> st, st2;
	std::vector<int> gone;
	int d[100], f[100];
	int count = 1;

	for (int i = 0; i < 100; i++)
		d[i] = 0;

	recurcive(nodes, d, f, 0, 1);

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

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

int d[110],f[110];
bool visited[110];
int timestamp = 1;

int n; vector<vector<int>> to;

void dfs(int u){
  if( visited[u] ){ return ;}
  visited[u] = true;
  d[u] = timestamp;
  timestamp++;
  for(auto ne : to[u]){
    if(visited[ne]){continue;}
    dfs(ne);
  }
  f[u] = timestamp;
  timestamp++;
  
  return ;
}
  

signed main(void){
  cin >> n;
  to.resize(n);
  for(int i = 0; i < n; i++){
    int u,k; cin >> u >> k; u--;
    for(int j = 0; j < k; j++){
      int a; cin >> a; a--;
       to[u].push_back(a);
    }
  }
  
  for(int i = 0; i < n; i++){ 
    sort(to[i].begin(),to[i].end());
  }
  
  for(int i = 0; i < n; i++){ dfs(i);}
  
  for(int i = 0; i < n; i++){ cout << i+1 << " " << d[i] << " "<< f[i] << endl;}
  
  return 0;
}