Go: package main

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

// repr state of visited node
// WHITE yet visit
// GEAY  visiting
// BLACK visited
const (
	WHITE int = iota
	GRAY
	BLACK
)

type dfsGraph struct {
	g      [][]int
	colors []int
	stime  []int // Start time of visiting node
	ftime  []int // Finish time of visiting node
}

var time int

func makeAdjList() [][]int {
	var n int
	fmt.Scanf("%d", &n)

	adj := make([][]int, n)
	for i := 0; i < n; i++ {
		adj[i] = make([]int, n)
	}

	sc := bufio.NewScanner(os.Stdin)
	for i := 0; i < n; i++ {
		sc.Scan()
		nodeInfo := strings.Split(sc.Text(), " ")
		outDegree, _ := strconv.Atoi(nodeInfo[1])

		if outDegree > 0 {
			for k := 0; k < outDegree; k++ {
				j, _ := strconv.Atoi(nodeInfo[k+2])
				j-- // convert 1 based to 0 based
				adj[i][j] = 1
			}
		}
	}

	return adj
}

func (dg dfsGraph) dfsVisit(u int) {
	// 頂点uを訪問中に設定
	dg.colors[u] = GRAY
	time++
	dg.stime[u] = time

	// uの隣接nodeを訪問
	for v := 0; v < len(dg.g); v++ {
		if dg.g[u][v] == 0 {
			continue // 辺がなければスキップ
		}

		// vが未訪問なら訪問
		if dg.colors[v] == WHITE {
			dg.dfsVisit(v)
		}
	}

	// 頂点uを訪問済みに設定
	dg.colors[u] = BLACK
	time++
	dg.ftime[u] = time
}

func (dg dfsGraph) dfs() {
	for i := 0; i < len(dg.g); i++ {
		if dg.colors[i] == WHITE {
			dg.dfsVisit(i)
		}
	}
}

func (dg dfsGraph) printDfsTime() {
	for i := 0; i < len(dg.g); i++ {
		fmt.Printf("%d %d %d\n", i+1, dg.stime[i], dg.ftime[i])
	}
}

func main() {
	adj := makeAdjList()
	colors := make([]int, len(adj))
	stime := make([]int, len(adj))
	ftime := make([]int, len(adj))
	graph := dfsGraph{adj, colors, stime, ftime}
	graph.dfs()
	graph.printDfsTime()
}

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

stack<int> S;
int n, x[10000][10000], a, b, c, d, _time=2;
int y[10000][3];

int main() {
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> b >> c;
		for (int j = 1; j <= c; j++) {
			cin >> d;
			x[i][d] = 1;
		}
	}
	S.push(1);
	y[1][1] = 1;
	while (!S.empty()) {
		a = S.top();
		for (int i = 1; i <= n; i++) {
			if (x[a][i] == 1 && y[i][0] == 0) {
				y[i][0] = 1;
				y[i][1] = _time;
				S.push(i);
				goto Exit;
			}
		}
		S.pop();
		y[a][2] = _time;
	Exit:;
		_time++;
	}
	for (int i = 1; i <= n; i++) {
		cout << i << ' ' << y[i][1] << ' ' << y[i][2] << endl;
	}
	return 0;
}

C++: // -*- mode:c++; coding:utf-8; c-basic-offset:2; -*-
// ALDS1_11_B: Depth First Search

#include <algorithm>
#include <cstdio>
#include <stack>
#include <utility>

using uint = unsigned int;

class Graph {
  const uint n_;
  uint* const g_;
  std::pair<int, int>* const visited_;
  uint time_;
  
public:
  Graph(uint n) : n_(n),
                  g_(new uint[(n_*n_)]),
                  visited_(new std::pair<int, int>[n_])
  {
    std::fill(g_, g_+(n_*n_), 0u);
  }

  ~Graph()
  {
    delete[] g_;
    delete[] visited_;
  }
  
  uint* operator [](uint i) const { return g_+(n_*i); }

  std::pair<int, int>* visited() const { return visited_; }

  void dfs()
  {
    init_visited();
    for (auto i = 0u; i < n_; ++i) {
      inner_dfs(i);
    }
  }

private:
  void init_visited()
  {
    time_ = 0u;
    for (auto i = 0u; i < n_; ++i) {
      visited_[i].first = -1;
    }
  }

  void inner_dfs(uint i)
  {
    if (visited_[i].first != -1) {
      return;
    }
    visited_[i].first = time_++;
    for (auto j = 0u; j < n_; ++j) {
      auto k = (*this)[i][j];
      if (k) {
        inner_dfs(j);
      }
    }
    visited_[i].second = time_++;
  }
};

int main()
{
  uint n;
  std::scanf("%u", &n);

  Graph g(n);

  uint u, k, v;
  for (auto i = 0u; i < n; ++i) {
    std::scanf("%u %u", &u, &k);
    for (auto j = 0u; j < k; ++j) {
      std::scanf("%u", &v);
      g[u-1][v-1] = 1;
    }
  }

  g.dfs();
  auto visited = g.visited();
  for (auto i = 0u; i < n; ++i) {
    std::printf("%u %d %d\n", i+1, visited[i].first+1, visited[i].second+1);
  }
}

// eof

C++: #define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <stdio.h>
#include <list>
#define black 0
//#define red 1
#define white -1
#define maxn 110
using namespace std;

int tot = 0;
int book[maxn] = {}, t[maxn][2] = {};
list<int> map[maxn];

void dfs(int u)
{
	if (book[u] == white) return; 
	else
		if (book[u] == black)
		{
			t[u][0] = ++tot;
			for (list<int>::iterator it = map[u].begin(); it != map[u].end(); it++)
				dfs(*it-1);
			book[u] = white;
			t[u][1] = ++tot;
		}
	return;
}
int main()
{
	int n;
	scanf("%d", &n);
	for (int i = 0; i < n; i++)
	{
		int u,k,v;
		scanf("%d%d", &u,&k);
		u--;
		for (int i = 0; i < k; i++)
		{
			scanf("%d", &v);
			map[u].push_back(v);
		}
	}
	dfs(0);
	for (int i = 0; i < n; i++)
	{
		printf("%d %d %d\n", i + 1, t[i][0], t[i][1]);
	}
	return 0;
}

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

int n,M[105][105],d[105],f[105],tt,P[105],nt[105];

int next(int u){
	for(int v=nt[u];v<n;v++){
		nt[u]=v+1;
		if(M[u][v]){
			return v;
		}
	}
	return -1;
}
void dfs_visit(int r){
	for(int i=0;i<n;i++){
		nt[i]=0;
	}
	stack<int> s;
	s.push(r);
	P[r]=1;
	tt++;
	d[r]=tt;
	while(s.size()!=0){
		int u= s.top();
		int v=next(u);
		if(v!=-1){
			if(P[v]==0){
				P[v]=1;
				tt++;
				d[v]=tt;
				s.push(v);
			}
		}
		else{
			P[u]=2;
			tt++;
			f[u]=tt;
			s.pop();
		}
	}
}

void dfs(){
	for(int i=0;i<105;i++){
		d[i]=f[i]=P[i]=0;
	}
	tt=0;
	for(int i=0;i<n;i++){
		if(P[i]==0){
			dfs_visit(i);
		}
	}
	for(int i=0;i<n;i++){
		printf("%d %d %d\n",i+1,d[i],f[i]);
	}
}

int main() {
	cin>>n;
	int u,k,v;
	for(int i=0;i<105;i++){
		for(int j=0;j<105;j++){
			M[i][j]=0;
		}
	}
	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;
		}
	}
	dfs();
	return 0;
}

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

typedef long long ll;
typedef pair<ll, ll> P;

#define pb push_back
#define rep(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, n) for(int i = a; i < (n); i++)
#define mod (ll)(1e9+7)
#define int ll
#define MAX 101

__attribute__((constructor))
void initial() {
  cin.tie(0);
  ios::sync_with_stdio(false);
}

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

void dfs(int u) {
  d[u] = ++tt;
  visited[u] = 1;
  rep(i, G[u].size()) {
    if(visited[G[u][i]] == 0) dfs(G[u][i]);
  }
  f[u] = ++tt;
}

signed main() {
	ll n;
  cin >> n;
  for(int i = 1; i <= n; i++) visited[i] = 0;
  rep(i, n) {
    ll u, k;
    cin >> u >> k;
    rep(j, k) {
      ll v;
      cin >> v;
      G[u].pb(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;
  }

	return 0;
}

C++: // ALDS1_11_B.cpp
// Graph I - Depth First Search

#include <iostream>
#include <vector>
#include <cstdio>
using namespace std;

struct Vertex
{
    int id;
    vector<int> adjList;
    int d = 0;
    int f = 0;
};

int cnt = 0;

void dfs(vector<Vertex> &V, int n, int i)
{
    if (V[i].d != 0 && V[i].f != 0)
        return;
    int len = V[i].adjList.size();
    V[i].d = ++cnt;

    for (int j = 0; j < len; j++) {
        int next = V[i].adjList[j];
        if (V[next].d == 0) {
            // V[next].d = ++cnt;
            dfs(V, n, next);
            //V[next].f = ++cnt;
        }
    }
    V[i].f = ++cnt;
}

int main()
{
    int n;
    cin >> n;
    vector<Vertex> V(n);
    int id;
    int num;
    for (int i = 0; i < n; i++) {
        cin >> id >> num;
        V[id-1].id = id-1;
        int tmp;
        for (int j = 0; j < num; j++) {
            cin >> tmp;
            V[id-1].adjList.push_back(tmp-1);
        }
    }
    for (int i = 0; i < n; i++)
        dfs(V, n, i);
    for (int i = 0; i < n; i++) {
        printf("%d %d %d\n", i + 1, V[i].d, V[i].f);
    }
    return 0;
}