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>
#include <unordered_set>
#include <unordered_map>
//#include "../cxx-prettyprint/prettyprint.hpp"

int timer = 0;
std::unordered_map<int, std::vector<int>> Adj;
std::unordered_set<int> nodes_visited;
std::unordered_map<int, int> discovered_time;
std::unordered_map<int, int> finished_time;

int dfs(int u) {
    nodes_visited.insert(u);
    discovered_time[u] = ++timer;
    for (int v : Adj[u]) {
        if (nodes_visited.find(v) == nodes_visited.end()) {
            dfs(v);
        }
    }
    finished_time[u] = ++timer;
}

int main() {
    int n;
    std::cin >> n;

    for (int i = 0; i < n; i ++) {
        int u, k;
        std::cin >> u >> k;
        std::vector<int> V(k);
        for (auto& v : V) {
            std::cin >> v;
        }
        Adj[u] = V;
    }

    dfs(1);

    for (int i = 1; i <= n; i ++) {
        std::cout << i << " " << discovered_time[i]
            << " " << finished_time[i] << std::endl;
    }
}

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

int M[101][101], cond[101], st[101], en[101], n;
stack<int> S;

void setAdj()
{
	int u, k, v;
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		for (int j = 0; j < k; j++) {
			cin >> v;
			M[u][v] = 1;
		}
	}
}

void dfs()
{
	int t = 1;
	S.push(1);
	cond[1] = -1; //?¨???????
	st[1] = t++;

	int i;
	while (!S.empty()) {
		int u = S.top();
		for (i = 1; i <= n; i++) {
			if (M[u][i] == 1) {
				M[u][i] = 0;
				break;
			}
		}
		if (i == n + 1 || cond[i] == 1) {
			cond[u] = 1;
			en[u] = t++;
			S.pop();
		}
		else {
			S.push(i);
			cond[i] = -1;
			st[i] = t++;	
		}
	}
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> n;
	setAdj();
	dfs();

	for (int i = 1; i <= n; i++) {
		cout << i << " " << st[i] << " " << en[i] << endl;
	}
	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], d[N], f[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;
	}
	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;
	d[r] = ++tt;

	while (!S.empty()) {
		int u = S.top();
		int v = next(u);
		if (v != -1) {
			if (color[v] == WHITE) {
				color[v] = GRAY;
				d[v] = ++tt;
				S.push(v);
			}
		}
		else {
			S.pop();
			color[u] = BLACK;
			f[u] = ++tt;
		}
	}
}

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

	for (int u = 0; u < n; u++) {
		if (color[u] == WHITE)dfs_visit(u);
	}
	for (int i = 0; i < n; i++) {
		cout << i + 1 << " " << d[i] << " " << f[i] << endl;
	}
}

int main() {
	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;
		}
	}

	dfs();

	return 0;
}

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

int main() {

	int n;
	std::cin >> n;

	std::vector<std::vector<int>> v(n);

	for (int i{}; i < n; ++i) {
		
		int u, k;
		std::cin >> u >> k;

		for (int j{}; j < k; ++j) {
			int t;
			std::cin >> t;
			v[u - 1].emplace_back(t - 1);
		}
	}


	std::vector<int> d(n,0), f(n,0);
	auto time = 0;

	for (int i{}; i < n; ++i)

		[&](int i_,auto gn_)->void {
			gn_(i_, gn_);
		}(i,
			[&](int here, auto fn)->void {
			
				if (d[here] <= 0)
					d[here] = ++time;

				for (const auto&e : v[here])
					if (d[e] <= 0)
						fn(e, fn);
	
				if (f[here] <= 0)
					f[here] = ++time;
				}
		);


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

C++: #include <iostream>
using namespace std;
int a[100][100]={},f[100]={},d[100]={},T[200]={};
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++){
			cin>>a[u][j];
		}
	}
	T[1]=1;
	f[1]=1;
	for(int time=2;time<=2*n;time++){
		for(int j=0;j<100;j++){
			if(a[T[time-1]][j]==0){
				d[T[time-1]]=time;
				T[time]=T[f[T[time-1]]-1];
				break;
			}
			else if(f[a[T[time-1]][j]]==0){
				f[a[T[time-1]][j]]=time;
				T[time]=a[T[time-1]][j];
				break;
			}
		}
	}
	for(int i=1;i<=n;i++){
		cout<<i<<" "<<f[i]<<" "<<d[i]<<endl;
	}
}

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

class Graph{
public:
	std::vector< std::vector<int> > A;
	std::vector<int> d, f;
	int n;

	Graph(int n);

	void DepthFirstSearch();
	int DepthFirstSearch_Rec(int id, int time);

};

Graph::Graph(int n){
	A.resize(n);
	d.resize(n);
	f.resize(n);
	for (int i = 0; i < n; i++){
		A[i].resize(n);
		for (int j = 0; j < n; j++){
			A[i][j] = 0;
		}
		d[i] = 0;
		f[i] = 0;
	}
	this->n = n;
}

void Graph::DepthFirstSearch(){
	int time = 0;
	for (int i = 0; i < n; i++){
		if (d[i] == 0) time = DepthFirstSearch_Rec(i, time + 1);
	}
	return;
}

int Graph::DepthFirstSearch_Rec(int id, int time){
	d[id] = time;
	for (int i = 0; i < n; i++){
		if (A[id][i] == 1 && d[i] == 0){
			time = DepthFirstSearch_Rec(i, time + 1);
		}
	}
	time++;
	f[id] = time;
	return time;
}

int main(){
	int n, u, k, v;
	scanf("%d", &n);
	Graph G(n);
	for (int i = 0; i < n; i++){
		scanf("%d%d", &u, &k);
		for (int j = 0; j < k; j++){
			scanf("%d", &v);
			G.A[u - 1][v - 1] = 1;
		}
	}

	G.DepthFirstSearch();

	for (int i = 0; i < n; i++){
		printf("%d %d %d\n", i+1, G.d[i], G.f[i]);
	}


	return 0;
}