Go: package main

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

type TimeRecord struct {
	discoverTime int
	finishTime   int
}

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

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

	timeRecordMap := make([]TimeRecord, n)
	childrenMap := make([][]int, n)
	for i := 1; i <= n; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		timeRecordMap[node-1] = TimeRecord{-1, -1}

		childNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		childrenMap[node-1] = make([]int, childNum)
		for j := 0; j < childNum; j++ {
			child, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			childrenMap[node-1][j] = child
		}
	}

	// TODO: always start with 1?
	timer := 1
	visit(1, &timer, childrenMap, timeRecordMap)
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

func visit(currentNode int, timer *int, childrenMap [][]int, timeRecordMap []TimeRecord) {
	if timeRecordMap[currentNode-1].discoverTime > 0 {
		return
	}
	children := childrenMap[currentNode-1]
	timeRecordMap[currentNode-1] = TimeRecord{*timer, timeRecordMap[currentNode-1].finishTime}
	(*timer)++
	for i := 0; i < len(children); i++ {
		visit(children[i], timer, childrenMap, timeRecordMap)
	}
	timeRecordMap[currentNode-1] = TimeRecord{timeRecordMap[currentNode-1].discoverTime, *timer}
	(*timer)++
}

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

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

int G[101][102];
int found[101];
int comp[101];   // complete.
int t;  // time.

typedef struct box{ int val; box* next; } box_t;  // stack.

box_t* init()
{
    box_t* head = new box_t;
    head->val = -1;
    head->next = NULL;
    return head;
}

bool isEmpty(box_t* head){ return (head->next == NULL ? true : false); }

box_t* push(box_t* head, int data)
{
    box_t* box = new box_t;
    box->val = data;
    box->next = head->next;
    head->next = box;
    return box;
}

int pop(box_t* head)
{
    if(isEmpty(head)){ return -1; }
    box_t* box = head->next;
    int val;
    head->next = box->next;
    val = box->val;
    delete box;
    return val;
}

int front(box_t* head)
{
    int val;
    if(isEmpty(head)){ return -1; }
    val = head->next->val;
    return val;
}

box_t* stack = init();

void search_loop(int i)
{
    int j, k;
    while(1){
        if(found[i] == 0){
            t++; found[i] = t;
            push(stack, i);
        }
        for(k = G[i][0]; G[i][k] != 0 && found[G[i][k]] != 0; k++);
        if(G[i][k] == 0){
            if(isEmpty(stack)){ return; }
            else{
                j = pop(stack);
                t++; comp[j] = t;
                i = front(stack);
            }
        }else{
            G[i][0] = k + 1;
            i = G[i][k];
        }
    };
    return;
}

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

    for(i = 1; i <= n; i++){
        cin >> a >> e;
        for(j = 1; j <= e; j++){
            cin >> b; G[a][j] = b; } }  // adjacent representation.

    for(i = 1; i <= n; i++){ found[i] = 0; comp[i] = 0; }
    t = 0;
    while(1){
        for(i = 1; i <= n; i++){
            if(found[i] == 0) break;
        }
        if(i > n) break;
        search_loop(i);
    };
    for(i = 1; i <= n; i++){ cout << i << " " << found[i] << " " << comp[i] << endl; }
    return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include<numeric>
#define REP(i, n) for(int i = 0; i < n; i++)
#define REPR(i, n) for(int i = n; i >= 0; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define INF 2e9
#define ALL(v) v.begin(), v.end()
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
class DFS{
public:
    int n;
    int time = 0;
    vector<vector<int> > G;
    vector<bool> flag;
    vector<int> d;
    vector<int> f;

    DFS(){
        cin >> n;
        G.resize(n);
        d.resize(n);//最初に発見された時刻
        f.resize(n);
        flag.resize(n,false);
        REP(i,n){
            int u,k; cin >>u>>k;
            u--;
            if(k != 0){
            REP(j,k){
                int a; cin >>a;
                G[u].push_back(a);
                G[u][j]--;
            }
            }
        }
        //time = 0;
    }
    
    void dfs(int now){
        //d[now] = time;
        flag[now] = true;
        d[now] = ++time;
        if(G[now].size() > 0){
            REP(i,G[now].size()){
                //time++;
                if(flag[G[now][i]] == false){
                    flag[G[now][i]] = true;
                    d[G[now][i]] = time+1;
                    dfs(G[now][i]);
                }
            }
        }
        f[now] = ++time;
        return;
    }

};

int main(){
    //cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	//cout << fixed << setprecision(15);
    DFS maze;
    REP(i,maze.n){
        if(maze.flag[i] == 0) {
            maze.dfs(i);
        }
    }
    REP(i,maze.n){
        cout << i+1 << ' ' << maze.d[i] << ' ' << maze.f[i] << endl;
    }

}

C++: 

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

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>

using namespace std;

const int MAX = 100;

void search(bool graph[MAX][MAX], int find[], int done[], int n, int u,int& count) {
	count++;
	find[u] = count;
	for (int i = 0; i < n; i++) {
		if (graph[u][i] && find[i] == 0) {
			search(graph, find, done, n, i, count);
		}
	}
	count++;
	done[u] = count;
}

int main() {
	bool check[MAX] = { false };
	int find[MAX] = { 0 };
	int done[MAX] = { 0 };
	bool graph[MAX][MAX] = { {false} };
	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 temp;
			cin >> temp;
			graph[u - 1][temp - 1] = true;
		}
	}

	int count = 0;
	for (int i = 0; i < N; i++) {
		if (find[i] == 0) {
			search(graph, find, done, N, 0, count);
		}
	}

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

	return 0;
}