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 <bits/stdc++.h>
#define REP(i, n) for (int i = 0; i < n; i++)
#define FOR(i, m, n) for (int i = m; i < n; i++)
#define ALL(v) (v).begin(), (v).end()
#define coutd(n) cout << fixed << setprecision(n)
#define ll long long int
#define vl vector<ll>
#define vi vector<int>
const int INF = 2147483647;
const ll MOD = 1000000007;

using namespace std;

int dfs(const int cur, const int par, int time, const vector<vi> &g, vi &d, vi &f) {
  if (d[cur] != 0)
    return time;
  d[cur] = time;
  time++;
  for (const auto u : g[cur]) {
    if (u == par)
      continue;
    time = dfs(u, cur, time, g, d, f);
  }
  f[cur] = time;
  time++;
  return time;
}

int main() {
  int n;
  cin >> n;
  vector<vi> g(n);
  REP(i, n) {
    int id, k;
    cin >> id >> k;
    id--;
    REP(j, k) {
      int u;
      cin >> u;
      u--;
      g[id].push_back(u);
    }
  }

  vi d(n, 0), f(n, 0);
  int time = 1;
  REP(i, n) { time = dfs(i, -1, time, g, d, f); }
  REP(i, n) { cout << i + 1 << " " << d[i] << " " << f[i] << endl; }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <stack>
#include <vector>
#include <math.h>
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <map>
#include <set>
#include <queue>
#include <list>
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,a,b) for(int i=int(a);i<int(b);++i)
#define crep(i) for(char i='a';i<='z';i++)
#define psortsecond(A,N) sort(A,A+N,[](const pii &a, const pii &b){return a.second<b.second;});
#define psortfirst(A,N) sort(A,A+N,[](const pii &a, const pii &b){return a.first<b.first;});
#define All(x) (x).begin(),(x).end()
int ctoi(const char c){
  if('0' <= c && c <= '9') return (c-'0');
  return -1;
}
using namespace std;
using pii  = pair<int,int>;
long long gcd(long long a, long long b){return (b == 0 ? a : gcd(b, a%b));}
long long lcm(long long a, long long b){return a*b/gcd(a,b);}
typedef long long ll;
#define MOD 1000000007
#define EPS 10e-8

ll C=0;
ll T[107],T1[107],T2[107];
vector<vector<ll>> V(107);

void dfs(int X){
    T[X]=1;
    C++;
    T1[X]=C;
    rep(i,V[X].size()){
        if(T[V[X][i]]==0){
            dfs(V[X][i]);
        }
    }
    C++;
    T2[X]=C;
}
 
int main(){
    ll N,A,B,C;
    cin >> N;
    rep(i,N){
        cin >> A >> B;
        rep(j,B){
            cin >> C;
            V[A].push_back(C);
        }
    }
    rep(i,N){
        if(T[i+1]==0){
            dfs(i+1);
        }
    }
    rep(i,N){
        cout << i+1 <<" "<< T1[i+1] << " " << T2[i+1] << endl;
    }
}

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

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

#define DEBUG (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() {
  }

  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) { return adjacentIds_[idx]; }

  void printTime();
  void printAdj();

private:
  int id_;
  int discover_time_;
  int finish_time_;

  int adjacentNum_;
  unique_ptr<int[]> adjacentIds_;

  bool isVisited_;
};


void Vertex::setAdjacency(const vector<int> &adjacentIds)
{
  if (adjacentIds_) assert(1);

  adjacentNum_ = adjacentIds.size();
  adjacentIds_ = unique_ptr<int[]>(new int[adjacentNum_]);

  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;
}