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++: using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define int long long
#define rep(i,n) for(int i = 0; i < (n); i++)
#define divup(a,b) ( ( (a) + ( (b) - 1u) ) / (b) ) // a/b の余り切り上げ
// #include <boost/multiprecision/cpp_int.hpp>
// using namespace boost::multiprecision;
const ll mod = 1000000007;
const ll mod9 = 1000000009;

ll d[109];
ll f[109];
ll u[109];
ll k[109];
ll v[109][109];
ll t=0;

ll  dfs(ll n){
    if(d[n]==0){
        t++;
        d[n]=t;
    // cout<<" d "<<n<<" "<<t<<endl;
    }

    ll ct=0;
    rep(i,k[n]){
        if(d[v[n][i]-1]==0) dfs(v[n][i]-1),ct++;
    }
    t++;
    f[n]=t;
    // cout<<" f "<<n<<" "<<t<<endl;
    return 0;
}

signed main(){
    ll n;
    cin>>n;
    rep(i,n){
        ll a;
        cin>>u[i]>>k[i];
        rep(j,k[i]){
            cin>>v[i][j];
        }
    }
    rep(i,n){
        if(d[i]==0) dfs(i);
    }
    rep(i,n){
        printf("%lld %lld %lld\n",i+1,d[i],f[i]);
    }
}

C++: 6
1 2 2 3
2 2 3 4
3 1 5
4 1 6
5 1 6
6 0

C++: #include <bits/stdc++.h>
using namespace std;

vector<vector<int>> g;
vector<int> d;
vector<int> f;
int t;

void dfs( int v )
{
	d[v] = ++t;
	for( int u : g[v] ) {
		if( d[u] ) continue;
		dfs( u );
	}
	f[v] = ++t;
}

int main()
{
	int n;
	cin >> n;
	g = vector<vector<int>>( n );
	d = vector<int>( n );
	f = vector<int>( n );
	for( int i = 0; i < n; i++ ) {
		int u, k;
		cin >> u >> k;
		u--;
		for( int j = 0; j < k; j++ ) {
			int v;
			cin >> v;
			v--;
			g[u].push_back( v );
		}
	}

	for( int i = 0; i < n; i++ ) {
		if( d[i] ) continue;
		dfs( i );
	}

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

C++: #include <iostream>

constexpr int MAXN = 100;
int V[MAXN][MAXN];
int D[MAXN];
int F[MAXN];

template<int STACK_SIZE, typename T = int>
class Stack {

public:
    Stack() {};

    void Push(T val) {
        if (top_ < STACK_SIZE) {
            stack_[top_++] = val;
        }else{
            std::cerr << "Stack over flow..." << std::endl;
            exit(-11);
        }
    };
    bool Pop() {
        if (top_ > 0) {
            stack_[--top_];
            return true;
        }
        return false;
    };

    T Top() {
        return stack_[top_ - 1];
    }

    int Size() {return top_;}


private:
    int max_size_ = STACK_SIZE;
    int top_ = 0;
    T stack_[STACK_SIZE];
};

Stack<MAXN, int> S;

int main() {

    int n;
    std::cin >> n;

    for (int i = 0; i < n; i++) {
        int id, e_num;
        std::cin >> id >> e_num;
        for (int j = 0; j < e_num; j++) {
            int t;
            std::cin >> t;
            V[id - 1][t - 1] = 1;
        }
    }
    int cnt = 0;
    for (int t = 0; t < n; t++) {
        if (D[t] == 0) {
            D[t] = ++cnt;
            S.Push(t);
            while (S.Size()) {
                for (int i = 0; i < n; i++) {
                    if ((V[S.Top()][i] == 1) && (D[i] == 0)) {
                        S.Push(i);
                        D[i] = ++cnt;
                        break;
                    }
                    if (i == n - 1) {
                        F[S.Top()] = ++cnt;
                        S.Pop();
                    }
                }
            }
        }
    }

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

}

C++: #include <bits/stdc++.h>
using namespace std;

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

int n, G[MAX + 1][MAX + 1];
int col[MAX + 1];
int d[MAX + 1], f[MAX + 1];
int t;
stack<int> S;

void init(int n) {
	for (int i = 1; i <= n; i++) {
		col[i] = WHITE;
		for (int j = 1; j <= n; j++)
			G[i][j] = 0;
	}
	t = 0;
}

void dfsvisit(int u) {
	col[u] = GRAY;
	d[u] = ++t;
	for (int v = 1; v <= n; v++)
		if (col[v] == WHITE && G[u][v])
			dfsvisit(v);
	col[u] = BLACK;
	f[u] = ++t;
}

void dfs() {
	for (int i = 1; i <= n; i++)
		if (col[i] == WHITE) dfsvisit(i);
}

void input() {
	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][v] = 1;
		}
	}
}

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

int main() {
	cin >> n;
	init(n);
	input();
	dfs();
	output();
}

C++: #include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<iostream>
using namespace std;

#define N_MAX 100

typedef struct _v {
    int k;
    int *v;
    int f;
    int l;
} Vertex;
Vertex Adj[N_MAX];

int t = 1;

void depth_search(int i) {
//    printf(" i %d\n", t);
    if (Adj[i].f == 0) {
        Adj[i].f = t;
//        printf("  Adj[%d] : k = %d f = %d\n", i, Adj[i].k, t);
    }
    else {
        t--;
        return;
    }

    for (int j = 0; j < Adj[i].k; j++) {
        t++;
//        printf("t:%d\n", t);
        depth_search(Adj[i].v[j]);
    }
    t++;
//    printf("t:%d\n", t);
    Adj[i].l = t;
//    printf(" Adj[%d].l = %d\n", i, Adj[i].l);
    return;
}

int main() {
    int n;

    cin >> n;

    for (int i = 0; i < n; i++) {
        int k;
        cin >> k >> k;
        Adj[i].k = k;
        Adj[i].v = new int[k];
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            Adj[i].v[j] = v - 1;
        }
        Adj[i].f = 0;
        Adj[i].l = 0;
    }

    for (int i = 0; i < n; i++) {
        depth_search(i);
        cout << i + 1 << " " << Adj[i].f << " " << Adj[i].l << endl;
    }

    return 0;
}

C++: #include<iostream>
#include<cstdio>
#define Lens 105
using namespace std;
int N;
int A[Lens][Lens];
int S[Lens], E[Lens];
int sum = 0;
char c[Lens];

void dns(int i)
{
	sum++;
	S[i] = sum;
	c[i] = 'g';
	for (int j = 1; j <= N; j++)
	{
		if (A[i][j] == 1 && c[j] == 'w')
			dns(j);
	}
	sum++;
	E[i] = sum;
	c[i] = 'b';
}

int main()
{
	cin >> N;
	for (int i = 1; i <= N; i++)
	{
		int k, n;
		cin >> k >> n;
		c[i] = 'w';
		for (int i = 0; i < n; i++)
		{
			int j;
			cin >> j;
			A[k][j] = 1;
		}
	}
	/*
	for (int i = 1; i <= N; i++)
	{
		for (int j = 1; j <= N; j++)
		{
			if (j > 1)
				cout << ' ';
			cout << A[i][j];
		}
		cout << endl;
	}
	*/
	for (int i = 1; i <= N; i++)
	{
		if (c[i] == 'w')
			dns(i);
	}
	for (int i = 1; i <= N; i++)
	{
		cout << i << ' ' << S[i] << ' ' << E[i] << endl;
	}
	return 0;
}