Go: package main

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

const N = 100

const (
	WHITE = iota
	GRAY
	BLACK
)

type Graph struct {
	M               [N][N]int
	color, d, f, nt [N]int
	tt              int
}

func (g *Graph) next(u, n int) int {
	for v := g.nt[u]; v < n; v++ {
		g.nt[u] = v + 1
		if g.M[u][v] != 0 {
			return v
		}
	}
	return -1
}

func (g *Graph) dfsVisit(r, n int) {
	var S []int
	S = append([]int{r}, S...)
	g.color[r] = GRAY
	g.tt++
	g.d[r] = g.tt

	for len(S) != 0 {
		u := S[0]
		v := g.next(u, n)
		if v == -1 {
			S = S[1:]
			g.color[u] = BLACK
			g.tt++
			g.f[u] = g.tt
			continue
		}

		if g.color[v] != WHITE {
			continue
		}

		g.color[v] = GRAY
		g.tt++
		g.d[v] = g.tt
		S = append([]int{v}, S...)
	}
}

func (g *Graph) dfs(n int) string {
	for i := 0; i < n; i++ {
		g.color[i] = WHITE
	}
	g.tt = 0

	for u := 0; u < n; u++ {
		if g.color[u] == WHITE {
			g.dfsVisit(u, n)
		}
	}

	var out bytes.Buffer
	for i := 0; i < n; i++ {
		out.WriteString(fmt.Sprintf("%d %d %d\n", i+1, g.d[i], g.f[i]))
	}

	return strings.TrimRight(out.String(), "\n")
}

func answer(reader io.Reader) string {
	sc := bufio.NewScanner(reader)
	sc.Split(bufio.ScanWords)

	sc.Scan()
	n, _ := strconv.Atoi(sc.Text())

	var g Graph
	for i := 0; i < n; i++ {
		sc.Scan()
		u, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		k, _ := strconv.Atoi(sc.Text())
		u--
		for j := 0; j < k; j++ {
			sc.Scan()
			v, _ := strconv.Atoi(sc.Text())
			v--
			g.M[u][v] = 1
		}
	}

	return g.dfs(n)
}

func main() {
	fmt.Println(answer(os.Stdin))
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define mod 1000000007
#define MAX 105
#define BLACK 0
#define GRAY 1
#define WHITE 2

int n;
int G[MAX][MAX];
int d[MAX], f[MAX], color[MAX];
int t;

void init();
void dfs();
void dfs_s(int s);

int main(){
    cin >> n;
    init();

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

    dfs();

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

void init(){
    t = 1;
    for(int i = 0; i < n; i++){
        d[i] = f[i] = 0;
        color[i] = WHITE;
        for(int j = 0; j < n; j++){
            G[i][j] = 0;
        }
    }
}

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

void dfs_s(int s){
    stack<int> S;
    S.push(s); color[s] = GRAY; d[s] = t;
    int now;

    while(!S.empty()){
        now = S.top();
        t++;
        bool fl = true;

        for(int i = 0; i < n; i++){
            if(G[now][i] == 1 && color[i] == WHITE){
                S.push(i); color[i] = GRAY; d[i] = t;
                now = i; fl = false; break;
            }
        }

        if(fl){
            int top = S.top(); S.pop();
            color[top] = BLACK; f[top] = t;
            now = top;
        }
    }
}

C++: #include <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>

#include <vector>
#include <memory>
using namespace std;

#define DEBUG (0)
#define USE_UNIQUE_PTR (0)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG

int g_time = 1;

class Vertex {
public:
  Vertex() :
    id_(-1),
    discover_time_(-1),
    finish_time_(-1),
    adjacentNum_(0),
    adjacentIds_(nullptr),
    isVisited_(false) { }

  ~Vertex() {
#if !USE_UNIQUE_PTR
    if (adjacentIds_)
      delete [] adjacentIds_;
#endif
  }

  void setAdjacency(const vector<int> &adjacentIds);

  inline void setId(int id) { id_ = id; }
  inline void setDiscoverTime(int time) { discover_time_ = time; }
  inline void setFinishTime(int time) { finish_time_ = time; }
  inline void setVisited(bool visited) { isVisited_ = visited; }

  inline int getId() { return id_; }
  inline int getDiscoverTime() { return discover_time_; }
  inline int getFinishTime() { return finish_time_; }
  inline bool getVisited() { return isVisited_; }
  inline int getAdjacentNum() { return adjacentNum_; }
  inline int getAdjacentId(int idx) {
    if (adjacentIds_ == nullptr || idx > adjacentNum_)
      return -1;
    return adjacentIds_[idx];
  }

  void printTime();
  void printAdj();

private:
  int id_;
  int discover_time_;
  int finish_time_;

  int adjacentNum_;
#if USE_UNIQUE_PTR
  unique_ptr<int[]> adjacentIds_;
#else
  int *adjacentIds_;
#endif // USE_UNIQUE_PTR

  bool isVisited_;
};


void Vertex::setAdjacency(const vector<int> &adjacentIds)
{

  adjacentNum_ = adjacentIds.size();
#if USE_UNIQUE_PTR
  adjacentIds_ = unique_ptr<int[]>(new int[adjacentNum_]);
#else
  adjacentIds_ = new int[adjacentNum_];
#endif // USE_UNIQUE_PTR

  for (int i = 0; i < adjacentNum_; i++)
  {
    adjacentIds_[i] = adjacentIds[i];
  }

}

void Vertex::printTime()
{
  printf("%d %d %d\n", id_, discover_time_, finish_time_);
}

void Vertex::printAdj()
{
  DPRINTF("%d %d", id_, adjacentNum_);
  for (int i = 0; i < adjacentNum_; i++) {
    printf(" %d", adjacentIds_[i]);
  }
  cout << endl;
}


void dfs(Vertex vertices[], int idx)
{

  DPRINTF("time %d  idx %d\n", g_time, idx);

  Vertex &vtx = vertices[idx];

  if (!vtx.getVisited())
  {
    vtx.setDiscoverTime(g_time);
    g_time++;
  }

  for (int i = 0; i < vtx.getAdjacentNum(); i++)
  {
    int id = vtx.getAdjacentId(i);
    dfs(vertices, id);
  }

  if (!vtx.getVisited())
  {
    vtx.setFinishTime(g_time);
    vtx.setVisited(true);
    g_time++;
  }

}


int main()
{
  int n;

  cin >> n; cin.ignore();
  DPRINTF("Node num %d\n", n);

  Vertex vertices[n+1];

  for (int i = 1; i <= n; i++)
  {
    int id;
    int num;

    cin >> id >> num;
    vertices[i].setId(id);
    DPRINTF("node %d (num %d)\n", id, num);

    vector<int> adjs;

    for (int j = 0; j < num; j++)
    {
      int adj;
      cin >> adj;

      adjs.push_back(adj);
    }

    if (adjs.size())
      vertices[i].setAdjacency(adjs);

    cin.ignore();
  }

#if DEBUG
  for (int i = 1; i <= n; i++) vertices[i].printAdj();
#endif

  for (int i = 1; i <= n; i++)
    if (!vertices[i].getVisited())
      dfs(vertices, i);

  for (int i = 1; i <= n; i++) vertices[i].printTime();

  return 0;
}

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

constexpr int WHITE=0;
constexpr int GRAY=1;
constexpr int BLACK=2;
constexpr int N=100;

int M[N][N];
int color[N], d[N], f[N], tt;
int nt[N];
int n;

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);
   color[r]=GRAY;
   d[r]=++tt;

   while(!S.empty()){
      int u=S.top();
      int v=next(u);
      if(v!=-1){
         if(color[v]==WHITE){
            color[v]=GRAY;
            d[v]=++tt;
            S.push(v);
         }
      }
      else{
         S.pop();
         color[u]=BLACK;
         f[u]=++tt;
      }
   }
}

void dfs(){
   for(int i=0; i<n; i++){
      color[i]=WHITE;
      nt[i]=0;
   }
   tt=0;
   for(int u=0; u<n; u++){
      if(color[u]==WHITE) dfs_visit(u);
   }
   for(int i=0; i<n; i++){
      cout << i+1 << " " << d[i] << " " << f[i] << endl;
   }
}

int main(){
   int u, k, v;
   cin >> n;
   for(int i=0; i<n; i++){
      for(int j=0; j<n; 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;
}