Go: package main

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

type TimeRecord struct {
	discoverTime int
	finishTime   int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	timeRecordMap := make([]TimeRecord, n)
	childrenMap := make([][]int, n)
	for i := 1; i <= n; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		timeRecordMap[node-1] = TimeRecord{-1, -1}

		childNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		childrenMap[node-1] = make([]int, childNum)
		for j := 0; j < childNum; j++ {
			child, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			childrenMap[node-1][j] = child
		}
	}

	timer := 1
	startNode := 1
	for {
		visit(startNode, &timer, childrenMap, timeRecordMap)
		startNode = findStartNode(childrenMap, timeRecordMap)
		if startNode < 0 {
			break
		}
	}
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

func findStartNode(childrenMap [][]int, timeRecordMap []TimeRecord) int {
	x := -1
	for node, timeRecord := range timeRecordMap {
		if timeRecord.discoverTime < 0 {
			x = node + 1
			break
		}
	}
	return x
}

func visit(currentNode int, timer *int, childrenMap [][]int, timeRecordMap []TimeRecord) {
	if timeRecordMap[currentNode-1].discoverTime > 0 {
		return
	}
	children := childrenMap[currentNode-1]
	timeRecordMap[currentNode-1] = TimeRecord{*timer, timeRecordMap[currentNode-1].finishTime}
	(*timer)++
	for i := 0; i < len(children); i++ {
		visit(children[i], timer, childrenMap, timeRecordMap)
	}
	timeRecordMap[currentNode-1] = TimeRecord{timeRecordMap[currentNode-1].discoverTime, *timer}
	(*timer)++
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

C++: #include <stdio.h>
#define MAX_N (105)

int n;
int G[MAX_N + 1][MAX_N + 1];
int d[MAX_N + 1];		// ????????????
int f[MAX_N + 1];		// ????????????
int time;
int dfs(int cur)
{
    d[cur] = time;
    for ( int i = 1; i <= n; i++ ) {
	if ( G[cur][i] && (d[i] == 0)) {
	    time++;
	    dfs(i);
	}
    }
    time++;
    f[cur] = time;
}

int main()
{
    scanf("%d", &n);
    
    for ( int i = 0; i < n; i++ ) {
	int u, k;
	scanf("%d %d", &u, &k);
	for ( int j = 0; j < k; j++ ) {
	    int v;
	    scanf("%d", &v);
	    G[u][v] = 1;
	}
    }

    time = 0;

    for ( int i = 1; i <= n; i++ ) {
	if ( d[i] == 0 ) {
	    time++;
	    dfs(i);
	}
    }


    for ( int i = 1; i <= n; i++ ) {
	printf("%d %d %d\n", i, d[i], f[i]);
    }

    return 0;
}

C++: #include<iostream>
#include<vector>
#define SIZE 1000000
using namespace std;

struct Stack{
  int line[SIZE];
  int top;
  void init(){
    top = 0;
  }
  bool empty(){
    return top==0;
  }
  void push(int x){
    line[top]=x;
    top ++;
  }
  int pop(){
    if(empty()) return -1;
    top--;
    return line[top];
  }
};
struct Node
{
  vector<int> toList;
  int dt;
  int ft;
};

Stack stack; 
int t; //time

void init(vector<Node>& nodes)
{
  t=0;
  stack.init();
  stack.push(0);
  for(int i=0;i<nodes.size();i++){
    nodes[i].ft=-1;
    nodes[i].dt=-1;
  }
}
void print(vector<Node> nodes)
{
  int n=nodes.size();
  for(int i=0;i<n;i++){
    cout<<i+1<<" "<<nodes[i].ft<<" "<<nodes[i].dt<<endl;
  }
}
void dfs(vector<Node>& nodes)
{ 
  int idx=stack.pop();
  //cout<<idx+1<<":";
  if(idx>=0){
    if(nodes[idx].ft<0){
      //cout<<" find";
      t++;
      nodes[idx].ft=t;
    }
    if(nodes[idx].toList.size()<=0){
      //cout<<" toList.size==0"<<endl;
      t++;
      nodes[idx].dt=t;
      dfs(nodes);
    }
    int count=0;
    for(int i:nodes[idx].toList){
      if(nodes[i].dt<0){
	//cout<<" jumpto "<<i+1<<endl;
	count++;
	stack.push(idx);
	stack.push(i);
	dfs(nodes);
      }
    }
    if(count==0 && nodes[idx].dt<0){
      //cout<<" finish"<<endl;
      t++;
      nodes[idx].dt=t;
      dfs(nodes);
    }
  }else{
    //cout<<"finish dfs"<<endl;
  }
}

int main()
{
  int n,u,k;
  cin>>n;
  vector<Node> nodes(n);
  for(int i=0;i<n;i++){
    cin>>u>>k;
    nodes[i].toList.resize(0);
    for(int j=0;j<k;j++){
      int tmp;
      cin>>tmp;
      nodes[i].toList.push_back(tmp-1);
    }
  }
  init(nodes);
  //print(nodes);

  dfs(nodes);
  print(nodes);
  return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;
typedef long long int ll;
vector<vector<int>>v;
vector<int>atime,btime;

int n;
int nowtime = 1;

void func(int i)
{
    if(atime[i] == 0) 
    {
        atime[i] = nowtime;
        nowtime++;
    }
    else return;
    for(auto x:v[i]) func(x);
    btime[i] = nowtime;
    nowtime++;
}

int main()
{
    int n;
    cin >> n;
    v.resize(n);
    atime.resize(n);
    btime.resize(n);
    for(int i = 0; i < n; i++)
    {
        atime[i]=0;
        btime[i]=0;
        int u,k;
        cin >> u >> k;
        for(int j = 0; j < k; j++)
        {
            int p;
            cin >> p;
            p--;
            v[i].push_back(p);
        }
    }
    for(int i = 0; i < n; i++) func(i);
    for(int i = 0; i < n; i++) cout << i+1 << " " << atime[i] << " " << btime[i] << endl; 
    
}

C++: //ALDS1_11_B:Depth First Search
#include <iostream>
#include <fstream>
#include <stdio.h>
#include <cstdlib>
#include <string>
#include <tuple>
#include <vector>
#include <map>
#include <list>
#include <set>
#include <queue>
#include <stack>
#include <algorithm>
#include <math.h>
#include <random>
#include <time.h>
#include <cassert>
using namespace std;
#define LL_MIN -9223372036854775808
#define LL_MAX 9223372036854775807

vector<int> v[101];
int d[101];
int f[101];
bool already[101];

int t = 1;

void dfs(int now){
    d[now] = t;
    t++;
    already[now] = 1;
    for(int i=0; i<v[now].size(); i++){
        if(!already[v[now][i]]) dfs(v[now][i]);
    }
    f[now] = t;
    t++;
}

int main(){
    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 tmp;
            cin >> tmp;
            v[u].push_back(tmp);
        }
        already[u] = false;
        sort(v[u].begin(), v[u].end());
    }

    for(int i=1; i<=n; i++){
        if(!already[i]) dfs(i);
    }

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