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 <bits/stdc++.h> 

#define int long long
#define double long double

#define REP(i, b) for(int i = 0; i < (b); i++)
#define REPS(i, b) for(int i = 1; i <= (b); i++)
#define ALL(v) (v).begin(), (v).end()

#define fi first
#define se second
#define pb push_back
#define mp make_pair

using namespace std;

using pi = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vs = vector<string>;
using vb = vector<bool>;
using vpi = vector<pi>;
using vvi = vector<vi>;
using vvb = vector<vb>;

const int INF = 1e16;
const int MOD = 1e9+7;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

int n;
vi d, f;
vvi G;
int t = 0;

void dfs(int n)
{
    t++;
    d[n] = t;
    for(int i : G[n]) if(d[i] == 0) dfs(i);
    t++;
    f[n] = t;
}

signed main()
{
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    cin >> n;
    G.resize(n+1);
    d.resize(n+1, 0);
    f.resize(n+1, 0);
    REP(i, n)
    {
        int u, k; cin >> u >> k;
        REP(j, k)
        {
            int v; cin >> v;
            G[u].pb(v);
        }
    }

    REPS(i, n)
    {
        if(d[i] == 0) dfs(i);
    }

    REPS(i, n) cout << i << " " << d[i] << " " << f[i] << endl;
}

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

class vertex{
public:
  vector<vertex*> to;
  bool visited;
  int num;
  int visit_time;
  int leave_time;
  vertex(){
    visited=false;
  }
  void dfs(){
    visited=true;
    visit_time=time();
    for(int i=0; i<to.size(); i++){
      if(!to[i]->visited) to[i]->dfs();
    }
    leave_time=time();
  }

  void print(){
    cout << num << " " << visit_time << " " << leave_time << endl;
  }

private:
  static int time(){
    static int ti=0;
    ti++;
    return ti;
  }
};

int main(){
  int n; cin >> n;
  vertex graph[n+1];

  int v, k, to;
  for(int i=0; i<n; i++){
    cin >> v >> k;
    graph[v].num = v;
    for(int j=0; j<k; j++){
      cin >> to;
      graph[v].to.push_back(&graph[to]);
    }
  }


  for(int v=1; v<=n; v++){
    if(!graph[v].visited) graph[v].dfs();
  }

  for(int v=1; v<=n; v++){
    graph[v].print();
  }
  
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n); i >= 0; i--)
#define REP(i, m, n) for (int i = (int)(m); i <= (int)(n); i++)
#define REPR(i, m, n) for (int i = (int)(m); i >= (int)(n); i--)
#define all(v) v.begin(), v.end()
typedef long long ll;

using Graph = vector<vector<int>>;

vector<bool> seen;
vector<int> first_order;
vector<int> last_order;

void dfs(const Graph &G, int v, int& ptr){
  first_order[v] = ptr++;

  seen[v] = true;
  for(int nv : G[v]){
    if(seen[nv] == true) continue;
    dfs(G, nv, ptr);
  }

  last_order[v] = ptr++;
}

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

  Graph G(n+1);
  rep(i, n){
    int u, k; cin >> u >> k;
    rep(j, k){
      int v; cin >> v;
      G[u].push_back(v);
    }
  }

  seen.assign(n+1, false);
  first_order.resize(n+1);
  last_order.resize(n+1);
  int ptr = 1;
  REP(i, 1, n){
    if(seen[i] == false){
      dfs(G, i, ptr);
    }
  }

  REP(i, 1, n){
    printf("%d %d %d\n", i, first_order[i], last_order[i]);
  }

  return 0;
}

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

int n;
int common_time = 1;

int adj_matrix[101][101] = {0};
int time_table[101][2] = {0};

void dfs(int node)
{
    if (time_table[node][0] == 0)
    {
        time_table[node][0] = common_time;
        common_time++;
    }
    else
    {
        return;
    }

    for (int i = 1; i <= n; i++)
    {
        if (adj_matrix[node][i] == 1)
        {
            dfs(i);
        }
    }

    time_table[node][1] = common_time;
    common_time++;
}

int main()
{
    cin >> n;

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

    for (int i = 1; i <= n; i++)
    {
        dfs(i);
    }

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

    return 0;
}

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

#define NUM 100
int node_num;
int V[NUM + 1][NUM + 1];
int d[NUM + 1];
int f[NUM + 1];
string color[NUM + 1];
int t;
int pos;
stack<int> s;

void createAdj(int n){
    for(int i = 1; i < NUM; i++){
        for(int j = 1; j < NUM; j++){
            V[i][j] = 0;
        }
    }

    for(int i = 0; i < n; i++){
        int num1;
        scanf("%d", &num1);

        int n;
        scanf("%d", &n);

        int num2;
        for(int j = 0; j < n; j++){
            scanf("%d", &num2);
            V[num1][num2] = 1;
        }
    }
}

int search(int n){
    for(int i = 1; i <= node_num; i++) {
        if(V[n][i] == 1 && color[i] == "white")
            return i;
    }
    return -1;
}

void dfs_init(){
    t = 0;
    for(int i = 0; i < NUM; i++){
        color[i] = "white";
    }
}

void dfs(){
    s.push(1);
    pos = 1;
    t++;
    color[1] = "grey";
    f[1] = t;

    while(s.size()){
        int u = s.top();
        int next_node = search(u);
        if(next_node != -1){
            pos = next_node;
            s.push(next_node);
            pos = next_node;
            t++;
            color[next_node] = "grey";
            d[next_node] = t;
        }else{
            s.pop();
            color[u] = "black";
            t++;
            f[u] = t;
        }
    }
}

void print(){
    for(int i = 1; i <= node_num; i++){
        printf("%d %d %d\n", i, d[i], f[i]);
    }
}

int main(void){
    scanf("%d", &node_num);
    createAdj(node_num);

    dfs_init();
    dfs();

    print();
}