Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveDfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

func nextInt(sc *bufio.Scanner) (int, error) {
	return strconv.Atoi(nextText(sc))
}

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

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

  std::pair<uint, uint>* 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 = 0u;
    }
  }

  void inner_dfs(uint i)
  {
    if (visited_[i].first) {
      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 %u %u\n", i+1, visited[i].first+1, visited[i].second+1);
  }
}

// eof

C++: #include <iostream>
#include <string>
#include <vector>
using namespace std;
typedef long long ll;
const int INF = 1<<30; 
const int MOD = 1e9 + 7;
const int MAX_N = 150;
int G[MAX_N][MAX_N], found[MAX_N], finished[MAX_N];
int Time, N;
void dfs(int u)
{
    Time++;
    found[u] = Time;
    for(int nextV = 1; nextV <= N; nextV++)
    {
        if(found[nextV] || G[u][nextV] == 0) continue;
        dfs(nextV);
    }
    Time++;
    finished[u] = Time;
}
void init()
{
    Time = 0;
    for(int i = 0; i <= N; i++)
    {
        found[i] = 0;
        finished[i] = 0;
    }
    for(int i = 0; i <= N; i++) for(int j = 0; j <= N; j++) G[i][j] = 0;
}
int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    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][v] = 1;
        }
    }
    int u = 1;
    while(u <= N)
    {
        if(found[u] == 0) dfs(u);
        u++;
    }
    for(int v = 1; v <= N; v++)
    {
        cout << v << " " << found[v] << " " << finished[v] << endl;
    }
    return 0;
}

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

void solve(){
  int n; cin >> n;
  vector<vector<int> > v(n + 1, vector<int>(n + 1, 0));
  for(int i = 0; i < n; i++){
    int u, k; cin >> u >> k;
    for(int j = 0; j < k; j++){
      int x; cin >> x;
      v[u][x] = 1;
    }
  }
  vector<int> d(n + 1), f(n + 1), c(n + 1, 0);
  stack<int> s;
  int t = 0;
  for(int j = 1; j <= n; j++){
    if(c[j] == 0){
      s.push(j);
      d[j] = ++t;
      c[j] = 1;
      while(s.size() != 0){
        t++;
        int x = s.top();
        int i;
        for(i = 1; i <= n; i++){
          if(v[x][i] == 1 && c[i] == 0){
            d[i] = t;
            c[i] = 1;
            s.push(i);
            break;
          }
        }
        if(i == n + 1){
          f[x] = t;
          s.pop();
        }
      }
    }
  }
  for(int i = 1; i <= n; i++){
    cout << i << " " << d[i] << " " << f[i] << endl;
  }
  return;
}

int main(){
  solve();
  return 0;
}

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

static const int N=100;
static const int white=0;
static const int gray=1;
static const int black=2;

int n,m[N][N];
int color[N],sta[N],fin[N],tt;
int nt[N];


int next(int u)
{
  for(int v=nt[u];v<n;v++)
  {
    nt[u]=v+1;
    if(m[u][v]) return v; //下に辺があれば返す
  }
  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;
  sta[r]= ++tt;

  while(!s.empty()) //空じゃない間
  {
    int u=s.top();
    int v= next(u);
    if(v != -1)
    {
      if(color[v]==white)
      {
        color[v]=gray;
        sta[v]= ++tt;
        s.push(v);
      }
    }
    else //v=-1
    {
      s.pop();
      color[u]=black;
      fin[u]= ++tt;
    }
  }
}

void dfs()
{
  //初期化
  for(int i=0;i<n;i++)
  {
    color[i]=white;
    nt[i]=0;
  }
  tt=0;

  //未訪問のuを始点としてdfsする
  for(int u=0;u<n;u++)
  {
    if(color[u]==white) dfs_visit(u);
  }
  for(int i=0;i<n;i++)
  {
    cout<<i+1<<" "<<sta[i]<<" "<<fin[i]<<endl;
  }
}

int main()
{
  //入力
  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; //辺があれば1と定義される
    }
  }

  dfs();
}