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<iostream>
#include<vector>
using namespace std;
int n;
vector < int > G[105];
int st[105] = {};
int et[105];
int t = 1;

void dfs(int v)
{
    if (st[v] != 0) return;
    st[v] = t;
    t++;
    for (auto& x : G[v]) {
        dfs(x);
    }
    et[v] = t;
    t++;
}

int main()
{
    cin >> n;
    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].push_back(v);
        }
    }
    for (int i = 1; i <= n; i++) dfs(i);
    for (int i = 1; i <= n; i++) {
        cout << i << " " << st[i] << " " << et[i] << endl;
    }
}

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

int n, t = 0;
int v[100][100];
int d[100], f[100], r[101];

void st(int id) {
	if (!r[id]) {
		r[id]++;
		d[id - 1] = ++t;
		for (int i = 0; i < n; i++)
			if (v[id - 1][i])
				st(i + 1);
		f[id - 1] = ++t;
	}
}

int main()
{
	cin >> n;

	for (int i = 0; i < n; i++) {
		int u, k, s;

		cin >> u >> k;

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

	for(int i = 0; i < n; i++)
		st(i);

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

	return 0;
}

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

#define WHITE 0
#define GRAY 1
#define BLACK 2

int G[101][101];
int color[101];
int n;
int d[101], f[101], t;

void search_loop(int i)
{
	int next;
	d[i] = ++t;
	color[i] = GRAY;
	cout << i << " " << t << endl;
	for(next = 1; next <= n; next++){
		if(G[i][next] > 0 && color[next] != BLACK){
			search_loop(next);
		}
	}
	f[i] = ++t;
	color[i] = BLACK;
	cout << i << " " << t << endl;
	return;
}

void dfs()
{
	int i;
	for(i = 1; i <= n; i++) color[i] = WHITE;  // initialize.

	t = 0;
	for(i = 1; i <= n; i++){
		if(color[i] == WHITE) search_loop(i);
	}
	for(i = 1; i <= n; i++){
		cout << i << " " << d[i] << " " << f[i] << endl;
	}
	return ;
}

int main()
{
	int i, j, k, e;
	cin >> n;
	for(i = 1; i <= n; i++){
		for(j = 1; j <= n; j++){
			G[i][j] = 0;
		}
	}
	do{
		cin >> i >> e;
		for(j = 1; j <= e; j++){
			cin >> k;
			G[i][k] = 1;
		}
	}while(i < n);

	dfs();

	return 0;
}

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

#define MAX 101

using namespace std;

int visited[MAX],d[MAX],f[MAX];
int tt=0;
vector<int> G[MAX];

void dfs(int u){
  d[u]=++tt;
  visited[u]=1;
  for(int i=0;i<G[u].size();i++){
    if(visited[G[u][i]]==0) dfs(G[u][i]);
  }
  f[u]=++tt;
}

int main(){
  int n; cin >> n;
  for(int i=1;i<=n;i++) visited[i]=0;
  for(int i=0;i<n;i++){
    int u,k; cin >> u >> k;
    for(int i=0;i<k;i++){
      int v; cin >> v;
      G[u].push_back(v);
    }
  }
  for(int i=1;i<=n;i++){
    if(visited[i]==0) dfs(i);
  }
  for(int i=1;i<=n;i++){
    cout << i << " " << d[i] << " " << f[i] << endl;
  }
}

C++: #include<iostream>
#include<vector>
#include<utility>
using namespace std;
vector<int> l[101];
int matrix[100][100];
pair<int,int> t[101];
bool visited[101];
int tim=0;
void dfs(int cur)
{
    tim+=1;
    t[cur].first=tim;
    //cerr<<"visiting "<<cur<<' '<<tim<<endl;
    visited[cur]=true;
    
    for(int i=0;i<l[cur].size();i++)
    {
        if((matrix[cur-1][l[cur][i]-1]==1)&&(visited[l[cur][i]]==false))
        {
            dfs(l[cur][i]);
        }
    }
    
    tim+=1;
    t[cur].second=tim;
    
    
}
int main()
{
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        int u,k;
        cin>>u>>k;
        for(int j=0;j<k;j++)
        {
            int tmp;
            cin>>tmp;
            l[u].push_back(tmp);
        }
    }
    
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            matrix[i][j]=0;
        }
    }
    
    visited[0]=false;
    for(int i=1;i<n+1;i++)
    {
        visited[i]=false;
        for(int j=0;j<l[i].size();j++)
        {
            matrix[i-1][l[i][j]-1]=1;
        }
    }
    
    for(int i=1;i<n+1;i++)
    {
        if(visited[i]==false)
            dfs(i);
    }
    
    for(int i=1;i<n+1;i++)
    {
        cout<<i<<" "<<t[i].first<<" "<<t[i].second<<endl;
    }
}

C++: #define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>

//#include<bits/stdc++.h>



using namespace std;




int main() {
	
	int n;
	cin>>n;
	vector<vector<int>>t(n,vector<int>(n));
	for(int i=0;i<n;i++){
		int x,r;cin>>r>>x;
		for(int j=0;j<x;j++){
			int w;cin>>w;w--;t[i].push_back(w);
		}
		sort(t[i].begin(),t[i].end());
	}
	stack<int>S;
	bool F[105]={};
	S.push(0);
	int p=1;
	F[0]=1;
	vector<int>G(n),H(n);
	int g=1;
	G[0]=1;
	while(S.size()){
		g++;
		int v=S.top();
		int a=-1;
		for(int i=0;i<t[v].size();i++){
			if(!F[t[v][i]]){
				a=t[v][i];break;
			}
		}
		if(a==-1){
			H[S.top()]=g;
			S.pop();
		}
		else{
			F[a]=1;
			G[a]=g;
			S.push(a);
		}
	}
	for(int i=0;i<n;i++){
		cout<<i+1<<" "<<G[i]<<" "<<H[i]<<endl;
	}
	

	
	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <stack>

#define MAX 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

using namespace std;


int adjacencyList[MAX + 1][MAX + 1];
int color[MAX + 1];
int d[MAX + 1];
int f[MAX + 1];
int n;



int minWhiteNode(int v)
{

	for (int i = 1; i <= n; i++) {
		if (color[i] == WHITE && adjacencyList[v][i] == 1 && i != v) {
			return i;
		}
	}
	return 	MAX + 1;
}


void dfs()
{
	stack<int> S;
	int cr;
	int timer = 1;

	S.push(1);
	color[1] = GRAY;
	d[1] = 1;

	while (S.size() > 0) 
	{
		cr = minWhiteNode(S.top());
		timer++;

		if (cr != MAX + 1) {
			S.push(cr);
			color[cr] = GRAY;
			d[cr] = timer;
		}
		else {
			int poped = S.top();
			S.pop();
			color[poped] = BLACK;
			f[poped] = timer;
		}
	}
}

int main(void)
{

	int u;
	int k;
	int v;


	cin >> n;

	for (int i = 0; i < n; i++) {
		cin >> u >> k;

		for (int j = 0; j < k; j++) {
			cin >> v;
			adjacencyList[u][v] = 1;
		}

	}

	dfs();

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

	return 0;
}