Go: package main

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

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve

const MAX = 100
const WHITE = 0
const GRAY = 1
const BLACK = 2

var time, n int

//隣接行列
var M [MAX][MAX]int

//d[i]: 最初にiを訪問した時刻。発見時刻
//f[i]: iの隣接リストを訪問し終えた時刻。完了時刻
var color, d, f [MAX]int

func dfs_visit(u int) {
	color[u] = GRAY
	time++
	d[u] = time
	//隣接を調べる
	for v := 0; v < n; v++ {
		if M[u][v] == 0 {
			continue
		}
		//隣接するvが、未訪問だった場合
		if color[v] == WHITE {
			dfs_visit(v)
		}
	}
	//訪問完了処理
	color[u] = BLACK
	time++
	f[u] = time
	//訪問完了
}

func dfs() {
	//初期化
	for u := 0; u < n; u++ {
		color[u] = WHITE
	}
	time = 0

	//未訪問のuを始点として、深さ優先探索
	for u := 0; u < n; u++ {

		if color[u] == WHITE {
			dfs_visit(u)
		}
	}

	for u := 0; u < n; u++ {
		fmt.Println(u+1, d[u], f[u])
	}
}

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()
	for i := 0; i < n; i++ {
		u, k := nextInt(), nextInt()
		M[u-1][u-1] = 0

		//fmt.Println(u, k)
		if k > 0 {
			for j := 0; j < k; j++ {

				v := nextInt()
				M[u-1][v-1] = 1

			}
		}

	}

	dfs()

}

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

vector<int>G[102];
int d[102],f[102];
bool vis[102];
int V;
int cur=0;
/*
void dfs(int id){
    cur++;
    d[id]=cur;
    vis[id]=true;
    for(int i=0;i<G[id].size();i++){
        if(!vis[G[id][i]])
            dfs(G[id][i]);
    }
    f[id]=cur;
}
*/
stack<int> s;
void dfs_visit(int id){
    s.push(id);
    cur++;
    d[id]=cur;
    while(!s.empty()){
        int u=s.top();
        int nex=-1;
        for(int i=0;i<G[u].size();i++){
            if(!vis[G[u][i]]) {
                nex=G[u][i];
                break;
            }
        }
        cur++;
        if(nex==-1){
            s.pop();
            f[u]=cur;
            vis[u]=true;
        }
        else{
            d[nex]=cur;
            s.push(nex);
        }
    }
}

void dfs(){
	int i;
    for(i=1;i<=V;i++){
        if(!vis[i]) dfs_visit(i);
    }
    for(i=1;i<=V;i++){
        cout<<i<<" "<<d[i]<<" "<<f[i]<<endl;
    }
}
int main(){
    cin>>V;
    memset(vis,false,sizeof(vis));
    for(int i=1;i<=V;i++){
        int id,k;
        cin>>id>>k;
        while(k--){
            int out;
            cin>>out;
            G[id].push_back(out);
        }
        sort(G[id].begin(),G[id].end());
    }
    dfs();
    return 0;
}

C++: #include <iostream>
#include <cstring>
#include <cstdlib>
#include <sstream>
#include <stack>
#include <queue>
#include <list>
#include <stdio.h>
#include <algorithm>
#define MAX 100000
using namespace std;
typedef long long ll;
int map[255][255];
int f[255],d[255],tt=0;
bool vis[255];
void dfs(int n,int u)
{
	if(vis[u]) return;
	vis[u]=true;
	tt++;
	d[u]=tt;
	for(int i=1;i<=n;i++)
	{
		if(map[u][i]) dfs(n,i);
	}
	tt++;
	f[u]=tt;
	return; 
}
int main()
{	
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
		{
			map[i][j]=0;
		}
	for(int i=0;i<n;i++)
	{
		int cur,k,u;
		cin>>cur>>k;
		while(k--)
		{
			cin>>u;
			map[cur][u]=1;
		}
	}
	for(int i=1;i<=n;i++)
	{
		vis[i]=false;
	}
	for(int i=1;i<=n;i++)
	{
		if(!vis[i]) dfs(n,i);
	}
	for(int i=1;i<=n;i++)
	{
		cout<<i<<" "<<d[i]<<" "<<f[i]<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <fstream>
#include <cassert>
#include <string.h>
#include <vector>
#include <map>
#include <stack>

enum Color
{
    kWhite,
    kGray,
    kBlack,
};

// 頂点数.
int n;

// 各頂点の隣接リスト表現.
std::map< int, std::vector<int> > adj_list;

// 各頂点の訪問状態を管理する.
std::vector<Color> c;

// 初回訪問時.
std::vector<int> d;

// 二回目訪問時.
std::vector<int> f;

void makeAdjListFromInput(int n)
{
    for (int i = 0; i < n; ++i)
    {
        int vertex;
        int degree;

        std::cin >> vertex;
        std::cin >> degree;

        assert(vertex <= n);
        assert(degree <= n);

        std::vector<int> adj_vertexes;

        for (int j = 0; j < degree; ++j)
        {
            int adj;
            std::cin >> adj;
            adj_vertexes.push_back(adj - 1);
        }

        adj_list[vertex - 1] = adj_vertexes;
    }
}

int nextVertex(int current)
{
    std::vector< int > adjs = adj_list[current];
    for (std::vector< int >::iterator it = adjs.begin(); it != adjs.end(); ++it)
    {
        if (c[(*it)] == kWhite)
            return (*it);
    }

    // 見つからなかった.
    return INT_MAX;
}

int firstVertex()
{
    for (int i = 0; i < n; ++i)
    {
        if (c[i] == kWhite)
            return i;
    }

    return INT_MAX;
}

void depthFirstSearch()
{
    int counter = 0;
    std::stack<int> tmp_stack;

    // 諸々初期化.
    for (int i = 0; i < n; ++i)
    {
        c.push_back(kWhite);
        d.push_back(0);
        f.push_back(0);
    }

    while (true)
    {
        int first = firstVertex();
        if (first == INT_MAX)
            break;
        tmp_stack.push(first);
        c[first] = kGray;
        d[first] = ++counter;

        while (! tmp_stack.empty())
        {
            int current = tmp_stack.top();
            int next = nextVertex(current);
            if (next != INT_MAX)
            {
                tmp_stack.push(next);
                c[next] = kGray;
                d[next] = ++counter;
            }
            else
            {
                int pop = tmp_stack.top();
                tmp_stack.pop();
                c[pop] = kBlack;
                f[pop] = ++counter;
            }
        }
    }
}

int main()
{
    std::cin >> n;

    makeAdjListFromInput(n);

    depthFirstSearch();

    for (std::map< int, std::vector<int> >::iterator it = adj_list.begin(); it != adj_list.end(); ++it)
    {
        int v = it->first;
        std::cout << v + 1 << " " << d[v] << " " << f[v] << std::endl;
    }

    return 0;
}

C++: #include <iostream>
#include <vector>
using namespace std;
typedef struct Node{
  vector<int> to;
  int d;
  int f;
}Node;

int n;
Node G[110];
int t = 0;

void dfs(int v){
  if(G[v].d > 0) return;
  G[v].d = ++t;
  for(int i=0; i<G[v].to.size(); i++){
    dfs(G[v].to[i]);
  }
  if(G[v].f < 0) G[v].f = ++t;
  return;
}

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