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<iostream>
using namespace std;

int m[101][101];
int visit[101];
int d[101];
int f[101];
int n, t;

void dfs(int u){
  visit[u] = 1;
  d[u] = t;
  t++;
  
  for(int i = 0; i < n; ++i){
    if(m[u][i] == 1 && visit[i] == 0){
      dfs(i);
    }
  }

  f[u] = t;
  t++;
}

main()
{
  int u, k, v;
  t = 1;

  cin >> n;
  for(int i = 0; i < n; ++i){
    cin >> u >> k;
    --u;
    for(int j = 0; j < k; ++j){
      cin >> v;
      v--;
      m[u][v] = 1;
    }
  }

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

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

  return (0);
}

C++: #include<iostream>
#include<algorithm>
#include<string>
#include<cstring>
#include<vector>
using namespace std;
#define clr(a,b) memset(a,b,sizeof(a))
int n;
int v,k,tm;
vector<int> graph[105];
int star[105],tend[105];//记录结束和开始
int vis[105];//纪律顶点是否被访问
void dfs(int u,int& deep)
{
    vis[u]=1;//表示该点已经被访问
    star[u]=deep++;
    sort(graph[u].begin(),graph[u].end());//排序
    for(int i:graph[u])
    {
        if(vis[i]==0){dfs(i,deep);}
    }
    tend[u]=deep++;
    return ;
}
int main()
{
    clr(star,0);clr(tend,0);
    clr(vis,0);
    cin>>n;
    for(int i=0;i<n;++i)
    {
        cin>>v>>k;
        while(k--)
        {
            cin>>tm;
            graph[v].push_back(tm);//连接的点
        }
    }
    int deep=1;
    dfs(1,deep);
    for(int i=1;i<=n;++i)
    {
        cout<<i<<" "<<star[i]<<" "<<tend[i]<<endl;
    }
    return 0;
}

C++: #include <algorithm>
#include <iostream>
#include <stack>
#include <cstdio>
using namespace std;
static const int MAX = 100;

int adj[MAX][MAX] = {0};
int n;

enum Color {
  WHITE,
  GRAY,
  BLACK,
};

struct node {
  Color color;
  int begin;
  int end;
};

node nodes[MAX];

void paint(int id, Color c) {
  static int time = 1;
  nodes[id].color = c;
  if (c == GRAY)
    nodes[id].begin = time;
  else if (c == BLACK)
    nodes[id].end = time;
  time++;
}

int next(int id) {
  for (int i = 0; i < n; i++) {
    if (adj[id][i] == 1 && nodes[i].color == WHITE) {
      return i;
    }
  }
  return -1;
}

void visit(int id) {
  stack<int> S;
  S.push(id);
  paint(id, GRAY);

  while (!S.empty()) {
    int u = S.top();
    int v = next(u);
    if (v > -1) {
      paint(v, GRAY);
      S.push(v);
    } else {
      S.pop();
      paint(u, BLACK);
    }
  }
}

void dfs() {
  for (int i = 0; i < n; i++) {
    nodes[i].color = WHITE;
  }
  for (int i = 0; i < n; i++) {
    if (nodes[i].color == WHITE)
      visit(i);
  }
}

void printNode(int i) {
  printf("%d %d %d\n", i+1, nodes[i].begin, nodes[i].end);
}

int main() {
  cin >> n;
  int id, nn, x;
  for (int i = 0; i < n; i++) {
    cin >> id >> nn;
    id--; // 0-based
    for (int j = 0; j < nn; j++) {
      cin >> x;
      x--; // 0-based
      adj[id][x] = 1;
    }
  }

  dfs();

  for (int i = 0; i < n; i++) {
    printNode(i);
  }
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <limits.h>
using namespace std;
bool flag[101];
int d[101];
int f[101];
vector<int> v[101];
int t;
void dfs(int node){
	flag[node] = true;
	d[node] = t;
	bool finished = true;
	if (finished && f[node] == 0) f[node] = t;
	for (int i = 0; i < v[node].size(); ++i){
		int tmp = v[node][i];
		if (!flag[tmp]){
			++t;
			dfs(tmp);
			++t;
		}
	}
	f[node] = t;
}
int main(){
	int n; scanf("%d",&n);
	for (int i = 0; i < n; ++i){
		int u, k; scanf("%d %d",&u,&k);
		int tmp;
		for (int j = 0; j < k; ++j){
			scanf("%d", &tmp);
			v[u].push_back(tmp);
		}
	}
	v[0].push_back(1);
	dfs(0);
	++t;
	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]+1 << '\n';
	}
}

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

const int N_MAX = 100;

int T = 1;
int d[N_MAX];
int f[N_MAX];
vector<int> v[N_MAX];

struct node{
    vector<int> near;
    int dis;
    int fin;
    bool found = false;
};

void dfs(int idx){
    d[idx] = T;
    ++T;
    rep(i, (int)v[idx].size()){
        int x = v[idx][i];
        if(d[x] == 0) dfs(x);
    }
    f[idx] = T;
    ++T;
}

int main() {
    int n;
    cin >> n;
    
    rep(i, n){
        int m, l;
        cin >> m >> l;
        --m;
        rep(j, l){
            int x;
            cin >> x;
            --x;
            v[m].push_back(x);
        }
    }
    
    rep(i, n){
        if(d[i] == 0) dfs(i);
    }
    
    rep(i, n){
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
    
    return 0;
}

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

int n, t = 0;
int v[100][100];
int d[100], f[100], r[101];

void st(int id) {
	if (!r[id]) {
		r[id]++;
		d[id - 1] = ++t;
		for (int i = 0; i < n; i++)
			if (v[id - 1][i])
				st(i + 1);
		f[id - 1] = ++t;
	}
}

int main()
{
	cin >> n;

	for (int i = 0; i < n; i++) {
		int u, k, s;

		cin >> u >> k;

		for (int j = 0; j < k; j++) {
			cin >> s;
			v[u - 1][s - 1] = 1;
		}
	}

	for(int i = 0; i < n; i++)
		st(i + 1);

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

	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <stack>
using namespace std;
stack<int> st;
int  v[102][101], n;
int  time[102][2];
int ct = 1;
inline void search(int t) {
	if(!time[t][0]) time[t][0] = ct++;
	int tf = 0;
	for (int a = 1; a <= n; a++) {
		if (v[t][a]) {
			st.push(a);
			for (int i = 1; i <= n; i++) {
				v[i][a] = 0;
			}
			search(st.top());
			tf = 1;
		}
	}
		
	if(!tf) {
		st.pop();
		time[t][1] = ct++;
		if(!st.empty()) search(st.top());
	}
}
int main() {
	for (int i = 1; i <= n; i++) {
		time[i][0] = 0;
	}
	st.push(1);
	int u, k, s;
	cin >> n;
	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= n; j++) {
			v[i][j] = 0;
		}
	}
	for (int i = 0; i < n; i++) {
		cin >> u;
		cin >> k;
		for (int j = 0; j < k; j++) {
			cin >> s;
			v[u][s] = 1;
		}
	}
	search(1);
	for (int i = 1; i <= n; i++) {
		cout << i << " " << time[i][0] << " " << time[i][1] << endl;
	}
	return 0;
}