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) doesAllAdjsVisited(vertices []vertex) bool {
	for _, vId := range v.adjs {
		adj := vertices[vId-1]
		if !adj.isVisited() {
			return false
		}
	}
	return true
}

func (v *vertex) isFirstVisit() bool {
	return v.firstVisitAt == 0
}

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

func (v *vertex) nextVertex(vertices []vertex) (vertexId, error) {
	for _, vId := range v.adjs {
		adj := vertices[vId-1]
		if !adj.isVisited() {
			return vId, nil
		}
	}
	return vertexId(-1), fmt.Errorf("illegal")
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	timestamp = timestamp + 1
	currentVertex := &vertices[currentId-1]
	if currentVertex.isFirstVisit() {
		currentVertex.firstVisitAt = timestamp
	}
	for !currentVertex.doesAllAdjsVisited(vertices) {
		nextVertexId, _ := currentVertex.nextVertex(vertices)
		timestamp = dfs(nextVertexId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

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)
	}

	dfs(vertexId(1), 0, 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++: #include <iostream>
#include <vector>

using namespace std;

int tim = 0;
vector<vector<int>> to;
vector<bool> reached;
vector<int> d;
vector<int> f;



void dfs(int point);

int main()
{
    int n;
    cin >> n;
    to.resize(n+1);
    for(int i = 1; i <= n; i++){
        int m;
        cin >> m;
        cin >> m;
        to[i].resize(m);
        for(int j = 0; j < m; j++){
            cin >> to[i][j];
        }
    }
    
    reached.resize(n+1);
    d.resize(n+1);
    f.resize(n+1);

    dfs(1);

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

    return 0;
}

void dfs(int point)
{
    tim++;
    reached[point] = true;
    d[point] = tim;
    for(int i = 0; i < to[point].size(); i++){
        if(!reached[to[point][i]]){
            dfs(to[point][i]);
        }
    }
    tim++;
    f[point] = tim;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long; using ull = unsigned long long;
//#define int ll
using vb = vector<bool>; using vvb = vector<vb>;
using vi = vector<int>; using vvi = vector<vi>;
using vl = vector<ll>; using vvl = vector<vl>;
template<class T> using V = vector<T>;
template<class T> using VV = vector<V<T>>;
#define fi first
#define se second
#define maxs(x,y) (x=max(x,y))
#define mins(x,y) (x=min(x,y))
using pii = pair<int,int>; using pll = pair<ll,ll>;
#define FOR(i,a,b) for(ll i = (a); i < (ll)(b); ++i)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,a,b) for(ll i = (ll)(b)-1;i >= a;--i)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(obj) (obj).begin(), (obj).end()
#define rALL(obj) (obj).rbegin(), (obj).rend()
#define eb(val) emplace_back(val)
const double PI = acos(-1), EPS = 1e-10;
const ll MOD = 1e9+7;
int t=0;
vi d,f;
vb used;
void dfs(int now,vvi &gr){
  if(used[now]) return;
  used[now] = true;
  t++;
  mins(d[now],t);
  REP(i,gr[now].size()){
    dfs(gr[now][i],gr);
  }
  t++;
  f[now] = t;
}
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  int n;
  cin >> n;
  d.assign(n,INT_MAX);
  f.assign(n,INT_MAX);
  used.assign(n,false);
  vvi gr(n);
  REP(i,n){
    int k;
    cin >> k >> k;
    REP(j,k){
      int v;
      cin >> v;
      gr[i].eb(v-1);
    }
  }
  REP(i,n){
    dfs(i,gr);
  }
  REP(i,n){
    cout << i+1 << " " << d[i] << " " << f[i] << endl;
  }
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <stack>

using namespace std;

const int max_v = 100;
vector<vector<int> > adj_list;
int d[max_v] = { 0 };
int f[max_v] = { 0 };
int discovered[max_v] = { 0 };
int t = 1;

// Depth-first Search ( Stack implementation)
void DFS(int v)
{
	stack<int> S;
	S.push(v);
	discovered[v] = 1;
	d[v] = t++;
	int i = 0;
	while (!S.empty()) {
		v = S.top();
		if (i < adj_list[v - 1].size()) {
			int u = adj_list[v - 1][i++];
			if (discovered[u] == 0) {
				discovered[u] = 1;
				d[u] = t++;
				S.push(u);
				i = 0;
			}
		}
		else {
			S.pop();
			f[v] = t++;
			i = 0;
		}
	}
}

int main(int argc, char** argv)
{
	// Input
	int n;
	int u, k;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		int v;
		vector<int> adj;
		for (int j = 0; j < k; j++) {
			cin >> v;
			adj.push_back(v);
		}
		adj_list.push_back(adj);
	}

	// Depth-first Search
	for (int i = 1; i <= n; i++) {
		if(discovered[i] == 0)
			DFS(i);
	}

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

	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<functional>
#include<queue>
#include<cmath>

using namespace std;

#if 0
所用時間:

感想:

#endif

int N, TIME=0, TIME_KEEP[100+5][2]={}; //TIME_KEEP[VERTEX] = [DISCOVER, FINISHED]
vector<int> vertices[100+5];
bool visited[100+5] = {};

void dfs(int cur);
bool check(int& remain, int N);

int main(){
    cin >> N;
    for(int i = 0; i < N; ++i){
        int index, itr;
        cin >> index >> itr;
        for(int i = 0; i < itr; ++i) {
            int buff;
            cin >> buff;
            vertices[index].push_back(buff);
        }
    }
    dfs(1);
    int remain;

    while(!check(remain, N)){//未発見のものがないか?
        //cout << "DETECTED" << endl;
        dfs(remain);
    }

    for(int i = 1; i <= N; ++i){
        cout << i << " " << TIME_KEEP[i][0] << " " << TIME_KEEP[i][1] << endl;
    }
}

void dfs(int cur){
    visited[cur] = true;
    TIME++;
    int discover = TIME;
    for(auto itr = vertices[cur].begin(); itr!=vertices[cur].end(); itr++)
        if(!visited[*itr]){
            dfs(*itr);
            visited[*itr] = true;
        } 
    TIME++;
    int finish = TIME;
    //cerr << "VERTEX:" << cur << " DISCOVER: " << discover << " FINISHED: " << finish << endl;
    TIME_KEEP[cur][0] = discover;
    TIME_KEEP[cur][1] = finish;
}

bool check(int& remain, int N){
    for(int i = 1; i <= N; ++i){
        if(!visited[i]) {
            remain = i;
            //cout << "remain:" << remain  << endl;
            return false;
        }
    }
    return true;
}