Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

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

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

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveDfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

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

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

struct ver{
    ll d;
    ll f;
};

ll t=0;
vector<vector<ll>> mat;
vector<ver> vers;

void find(ll pos) {
    if(vers[pos].d == 0){
        t++;
        vers[pos].d = t;
        for(ll i:mat[pos]) {
            find(i);
        }
        if(vers[pos].f == 0) {
            t++;
            vers[pos].f = t;
        }
    }
}

int main() {
    ll n;
    cin >> n;
    for(ll i=0;i<n;i++) {
        ll u,k;
        cin>>u>>k;
        vector<ll> aaa;
        for(ll j=0;j<k;j++) {
            ll tmp;
            cin>>tmp;
            aaa.push_back(tmp-1);
        }
        mat.push_back(aaa);
    }
    for(ll i=0;i<n;i++) {
        vers.push_back(ver{0,0});
    }
    for(ll i=0;i<n;i++) {
        if(vers[i].d == 0)find(i);
    }
    for(ll i=0;i<n;i++) {
        cout << i+1<<" "<<vers[i].d<<" "<<vers[i].f<<endl;
    }
}

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

using namespace std;
const int INF = 1001001001;

void step1(vector< vector<int> >& edges, vector<int>& d, vector<int>& f, vector<int>& color, int node, int& time)
{
    // stackを使用
    stack<int> S;
    S.push(node);
    d[node] = ++time;
    color[node] = 1;
    while(!S.empty())
    {
        node = S.top();
        if(color[node] != 2){
            bool flag = true;
            for(int e : edges[node])
            {
                if(color[e] == 0)
                {
                    S.push(e);
                    d[e] = ++time;
                    color[e] = 1;
                    flag = false;
                    break;
                }
            }
            if(flag) color[node] = 2;
        }
        else
        {
            f[node] = ++time;
            S.pop();
        }
    }
}

void step2(vector< vector<int> >& edges, vector<int>& d, vector<int>& f, vector<int>& color, int node, int& time)
{
    d[node] = ++time;
    color[node] = 1;
    for(int e : edges[node])
        {
            if(color[e] == 0) step2(edges, d, f, color, e, time);
        }
    
    f[node] = ++time;
}

void dfs(vector< vector<int> >& edges, vector<int>& d, vector<int>& f, vector<int>& color, int n)
{
    int time=0;
    for(int i=0;i<n;++i)
    {
        if(color[i] == 0) step2(edges, d, f, color, i, time);
    }
}

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

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

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;





//用栈实现深度优先搜索


/**
 * color 标记访问状态的数组，
 * M[N][N] 邻接矩阵 如果存在定点i到顶点j的边，则M[i][j]=trul
 * Stack 栈，暂存访问过程中的顶点
**/
int n,M[N][N];
int color[N],d[N],f[N],tt;
int nt[N];


//按序号，获取和u相邻的v
int next(int u){
    for(int v=nt[u];v<n;v++){
        nt[u]=v+1;
        if(M[u][v]) return v;
    }
    return -1;
}

//用栈实现深度优先搜索
void dfs(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(){
    //初始化
    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(u);
    }
    for(int i=0;i<n;i++){
        cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;
    }
    return;
}
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 i=0;i<k;i++){
            cin>>v;
            v--;
            M[u][v]=1;
        }
    }

    dfs();
    return 0;
}

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

template<typename T>
T gcd(T a, T b)
{
	return b ? gcd(b, a%b) : a;
}

template<typename T>
T lcm(T a, T b)
{
	return a / gcd(a, b) * b;
}

//(a^e)%mod
template<typename T>
T power(T a, T e, T mod)
{
	if(e == 0)
	{
		return 1;
	}
	if(e % 2 != 0)
	{
		//a^e=a^(e-1)*a
		return (power(a, e - 1, mod) * a) % mod;
	}
	T res = power(a, e / 2, mod);
	//a^e=a^(e/2)*a^(e/2)
	return (res * res) % mod;
}

template<typename T>
class Tree
{
private:
public:
	T data;
	Tree* parent = NULL;
	std::vector<Tree*> children;
	void setData(T x)
	{
		data = x;
	}
	void setParent(Tree* t)
	{
		parent = t;
	}
	void addChild(Tree* t)
	{
		children.push_back(t);
	}
	Tree(){}
	~Tree(){}
	
};

template<typename T>
class Graph
{
public:
	T index;
	vector<T> edge;
	void setEdge(T t)
	{
		edge.push_back(t);
	}
	Graph(){}
	~Graph(){}
};

Graph<int> G[101];
pair<int, int> timeStamp[101] = {};
int cn = 1;

void rec(int now)
{
	if(timeStamp[now].first != 0)
	{
		return;
	}
	timeStamp[now].first = cn++;
	for (auto t : G[now].edge)
	{
		rec(t);
	}
	timeStamp[now].second = cn++;
}

int main()
{
	using namespace std;
	int n;
	cin >> n;
	for (int i = 0; i < n; ++i)
	{
		int index, k;
		cin >> index >> k;
		G[index].index = index;
		for (int j = 0; j < k; ++j)
		{
			int in;
			cin >> in;
			G[index].setEdge(in);
		}
		sort(G[index].edge.begin(), G[index].edge.end());
	}
	for (int i = 1; i <= n; ++i)
	{
		rec(i);
	}
	for (int i = 1; i <= n; ++i)
	{
		cout << i <<" " << timeStamp[i].first << " " << timeStamp[i].second << endl;
	}
	return 0;
}