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<cstdio>
#define MAX_N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2
using namespace std;

int n, u, k, v;
int Adj[MAX_N][MAX_N];
int d[MAX_N], f[MAX_N], color[MAX_N];
int tt;

void initialize(){
	for(int i = 0; i < n; i++){
		for(int j = 0; j < n; j++){
			Adj[i][j] = 0;
		}
	}
}

void check_adj(){
	Adj[u][v] = 1;
}

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

void dfs(){
	tt = 0;
	for(int i = 0; i < n; i++) color[i] = WHITE;
	for(int i = 0; i < n; i++){
		if(color[i] == WHITE) dfs_visit(i);
	}
	for(int i = 0; i < n; i++){
		printf("%d %d %d\n", i + 1, d[i], f[i]);
	}
}

/* void print_adj(){
	for(int i = 0; i < n; i++){
		for(int j = 0; j < n; j++){
			cout << Adj[i][j];
			if(j == n - 1) cout << endl;
			else cout << " ";
		}
	}
} */

int main(void){
	cin >> n;
	initialize();
	for(int i = 0; i < n; i++){
		cin >> u;
		u--;
		cin >> k;
		for(int j = 0; j < k; j++){
			cin >> v;
			v--;
			check_adj();
		}
	}
	dfs();
	//print_adj();

	return 0;
}

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

#define INPUT_FROM_FILE (0) 
#if INPUT_FROM_FILE
#include <fstream>
#endif

int time_stamp = 0;
std::vector<int> d;
std::vector<int> f;

void dfs(std::vector<std::vector<int> > &G, std::vector<bool> &is_searched, int i){
	if(is_searched[i]){
		//time++;
		return;
	}
	is_searched[i] = true;
	time_stamp++;
	d[i] = time_stamp;

	for(int j = 0; j < G[i].size(); j++){
		dfs(G, is_searched, G[i][j]);
	}
	time_stamp++;
	f[i] = time_stamp;
	return;
}

int main(int argc, char **argv){
	int n, u, k, v;
	std::vector<std::vector<int> > G;
	std::vector<bool> is_searched;

#if INPUT_FROM_FILE
	std::ifstream ifs("test.txt");
	//FILE *fp = fopen("test.txt", "r");
#endif

#if INPUT_FROM_FILE
	ifs >> n;
#else
	std::cin >> n;
#endif

	G.resize(n);
	is_searched.resize(n, false);
	d.resize(n, 0);
	f.resize(n, 0);
	for(int i = 0; i < n; i++){
#if INPUT_FROM_FILE
		ifs >> u >> k;
#else
		std::cin >> u >> k;
#endif
		G[u - 1].resize(k);
		for(int j = 0; j < k; j++){
#if INPUT_FROM_FILE
			ifs >> v;
#else
			std::cin >> v;
#endif
			G[u - 1][j] = v - 1;
		}
	}

	for(int i = 0; i < n; i++){
		dfs(G, is_searched, i);
	}

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

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

//次の点へ移動とかする関数
int next_point(int point, int (&a)[100][100], int (&num)[100], int (&back)[100], int time[100][2]){
	int next = a[point][num[point]]-1;
	
	//行先が探索終了しているしている場合、pointを返す
	if(a[next][1] == 0 && time[next][1] != 0){
		a[point][1] -= 1;
		return point;
	}
	
	back[next] = point;
	a[point][1] -= 1;
	return next;
}

int main(void){
	int a[100][100];
	int back[100];				//back[]:現在いる点の始点
	int time[100][2];	//time[i][0]:発見時刻,time[i][1]:探索終了時間
	int m, time_now=1, point=0;	//point:現在探索している点
	int num[100];
	
	cin >> m;
	
	for(int i=0; i<m;i++){
		cin >> a[i][0];
		cin >> a[i][1];
		
		for(int j=2; j<a[i][1]+2; j++){
			cin >> a[i][j];
		}
	}

	//ここまで入力
	//ここから↓
	
	//numを2に初期化
	for(int i=0; i<100; i++){
		num[i] = 2;
		time[i][0] = INT_MAX;
	}
	
	time[0][1] = -1;
	
	time[point][0] = time_now++;
	while(time[0][1] == -1){
		
		//矢印が出ていない場合
		if(a[point][1] == 0){
			time[point][1] = time_now++;	//探索終了時刻を決定
			point = back[point];	//始点へ移動
		}
		
		//矢印が出ている場合
		if(a[point][1] != 0){
			point = next_point(point, a, num, back, time);
			num[back[point]] += 1;
			if(time[point][0] > time_now) time[point][0] = time_now++;	//探索開始時刻を決定
		}
	}
	
	//出力
	for(int i=0; i<m; i++){
		cout << i+1 << " " << time[i][0] << " " << time[i][1] << "\n";
	}
	
	return 0;
}

C++: #include<iostream>
#include<stack>
#include<queue>
using namespace std;
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

string col[3] = {"WHITE", "GRAY", "BLACK"};
struct Node{
	int color, d, f;
	queue<int> Q;
};

int main(){
	int n;
	cin >> n;
	Node node[n + 1];
	stack<int> move;
	for(int i = 1; i <= n; i++){
		int u, k, v;
		cin >> u >> k;
		node[u].color = WHITE;
		while(k--){
			cin >> v;
			node[u].Q.push(v);
 		}
	}

	int start = 1;
	int tt = 1, p, next;

	do{
		move.push(start);
		node[start].color = GRAY;
		node[start].d = tt;
		tt++;

		while(!move.empty()){
			p = move.top();
			//cout << "Is at " << p << endl;
			if(node[p].Q.empty()){
				//cout << "Cant move from here!" << endl;
				node[p].color = BLACK;
				node[p].f = tt;
				move.pop();
				tt++;
			} else {
				next = node[p].Q.front();
				if(node[next].color == WHITE){
					//cout << "Moving to " << next << endl;
					move.push(next);
					node[next].color = GRAY;
					node[next].d = tt;
					tt++;
				} else {
					//cout << "Cant move to " << next << endl;
					node[p].Q.pop();
				}
			}
			/*
			for(int i = 1; i <= n; i++)
				cout << i << "'s color is " << col[node[i].color] << endl;
			*/
		}

		start = -1;
		for(int i = 1; i <= n; i++){
			if(node[i].color == WHITE){
				start = i;
				break;
			}
		}
		//cout << "start = " << start << endl;
	} while (start > 0);
	

	for(int i = 1; i <= n; i++){
		cout << i << " " << node[i].d << " " << node[i].f << endl;
	}
	return 0;
}