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 <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)
{
  if (adjacentIds_) assert(1);

  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);

  return 0;
}

C++: #include<stdio.h>
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

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

void dfs_visit(int u) {
  int v;
  color[u] = GRAY;
  d[u] = ++tt;
  for ( v = 0; v < n; v++ ) {
    if ( M[u][v] == 0) continue;
    if ( color[v] == WHITE )
      dfs_visit(v);
  }
  color[u] = BLACK;
  f[u] = ++tt;
}

void dfs() {
  int u;
  for ( u = 0; u < n; u++ ) color[u] = WHITE;
  tt = 0;

  for ( u = 0; u < n; u++ )
    if ( color[u] == WHITE ) dfs_visit(u);
  for ( u = 0; u < n; u++ )
    printf("%d %d %d\n", u + 1, d[u], f[u]);
}

int main() {
  int u, v, k, i, j;

  scanf("%d", &n);
  for ( i = 0; i < n; i++ )
    for ( j = 0; j < n; j++ ) M[i][j] = 0;

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

  dfs();

  return 0;
}

C++: #include<cstdio>
#include<array>
#include<vector>
#include<stack>
using namespace std;
const int MAX_V=101;
array<int,MAX_V> open{0};
array<int,MAX_V> close{0};
array<vector<int>,MAX_V> edge;
int t=0;

void dfs(int f){
  open[f]=++t;
  for(int a:edge[f]){
    if(open[a]==0){
      dfs(a);
    }
  }
  close[f]=++t;
}

int main(){
  int n;scanf("%d",&n);
  for(int i=0;i<n;i++){
    int u;scanf("%d",&u);
    int k;scanf("%d",&k);
    for(int j=0;j<k;j++){
      int v;scanf("%d",&v);
      edge[u].push_back(v);
    }
  }
  dfs(1);
  for(int i=0;i<n;i++){
    printf("%d %d %d\n",i+1,open[i+1],close[i+1]);
  }
}

C++: #include <iostream>

constexpr int MAXN = 100;
int V[MAXN][MAXN];
int D[MAXN];
int F[MAXN];

template<int STACK_SIZE, typename T = int>
class Stack {

public:
    Stack() {};

    void Push(T val) {
        if (top_ < STACK_SIZE) {
            stack_[top_++] = val;
        }else{
            std::cerr << "Stack over flow..." << std::endl;
            exit(-11);
        }
    };
    bool Pop() {
        if (top_ > 0) {
            stack_[--top_];
            return true;
        }
        return false;
    };

    T Top() {
        return stack_[top_ - 1];
    }

    int Size() {return top_;}


private:
    int max_size_ = STACK_SIZE;
    int top_ = 0;
    T stack_[STACK_SIZE];
};

Stack<MAXN, int> S;

int main() {

    int n;
    std::cin >> n;

    for (int i = 0; i < n; i++) {
        int id, e_num;
        std::cin >> id >> e_num;
        for (int j = 0; j < e_num; j++) {
            int t;
            std::cin >> t;
            V[id - 1][t - 1] = 1;
        }
    }
    S.Push(0);

    int cnt = 1;
    D[0] = cnt;
    while (S.Size()) {
        for (int i = 0; i < n; i++) {
            if ((V[S.Top()][i] == 1) && (D[i] == 0)) {
                S.Push(i);
                D[i] = ++cnt;
                break;
            }
            if (i == n - 1) {
                F[S.Top()] = ++cnt;
                S.Pop();
            }
        }
    }

    for (int i = 0; i < n; i++) {
        std::cout << i + 1 << " " << D[i] << " " << F[i] << std::endl;
    }

}