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 <iostream>

using namespace std;

int V[101][101];
int n;

int d[101];
int f[101];

int t = 1;
void dfs(int src){
  t++;
  for(int i=1;i<=n;i++){
    if(V[src][i] != 0 && !d[i]){
      d[i] = t;
      dfs(i);
      t++;
    }
  }
  f[src] = t;
}
int main(){
  int  src, dst, num, non_visited;
  cin >> n;
  for(int i=1;i<=n;i++){
    d[i] = 0; f[i] = 0;
  }
  for(int i=1;i<=n;i++){
    cin >> src >> num;
    for(int j=0;j<num;j++){
      cin >> dst;
      V[src][dst] = 1;
    }
  }
  non_visited = 1;
  do{
    d[non_visited] = t;
    dfs(non_visited);
    non_visited = 0;
    for(int i=1;i<=n;i++){
      if(!d[i]){
        non_visited = i;
        break;
      }
    }
    t++;
  }while(non_visited);

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

C++: #include <cstdio>
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n, M[N][N];
int color[N], d[N], f[N], tt;

void dfs_visit(int u) {
	int v;
	color[u] = GRAY;
	d[u] = ++tt;
	for (v = 0; v < n; ++v) {
		if (!M[u][v]) continue;
		if (color[v] == WHITE) {
			dfs_visit(v);
		}
	}
	color[u] = BLACK;
	f[u] = ++tt;
}

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

	for (int u = 0; u < n; ++u) {
		if (color[u] == WHITE) dfs_visit(u);
	}
	for (int u = 0; u < n; ++u) {
		printf("%d %d %d\n", u + 1, d[u], f[u]);
	}
}

int main() {
	int u, v, k;

	scanf("%d", &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) {
		scanf("%d %d", &u, &k);
		u--;
		for (int j = 0; j < k; ++j) {
			scanf("%d", &v);
			v--;
			M[u][v] = 1;
		}
	}

	dfs();
}

C++: #include<algorithm>
#include<cassert>
#include<climits>
#include<cmath>
#include<cstring>
#include<deque>
#include<functional>
#include<iomanip>
#include<iostream>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<vector>

using namespace std;

using lint = long long;
using P = pair<int, int>;
using LLP = pair<long long, long long>;

#define REP(i, x, n) for(int i = (x), i##_len = int(n) ; i < i##_len ; ++i)
#define rep(i, n) for(int i = 0, i##_len = int(n) ; i < i##_len ; ++i)
#define reps(i, n) for(int i = 1, i##_len = int(n) ; i <= i##_len ; ++i)
#define rrep(i, n) for(int i = int(n) - 1 ; i >= 0 ; --i)
#define rreps(i, n) for(int i = int(n) ; i > 0 ; --i)
#define SORT(x) sort((x).begin(), (x).end())
#define SORT_INV(x) sort((x).rbegin(), (x).rend())
#define TWINS(x) cout << ((x) ? "Yay!" : ":(") << endl

constexpr int IINF = (1 << 30) - 1;
constexpr long long LLINF = 1LL << 61;
constexpr double EPS = 1e-8;

const int dx4[] = {1, 0, -1, 0}, dy4[] = {0, 1, 0, -1};
const int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dy8[] = {0, -1, -1, -1, 0, 1, 1, 1};

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

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

void dfs(int v, int& t, vector<int>& d, vector<int>& f, const vector< vector<int> >& g){
    d[v] = t++;

    for(auto to : g[v]){
        if(d[to] < 0){
            dfs(to, t, d, f, g);
        }
    }

    f[v] = t++;

    return;
}

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

    int n;
    cin >> n;

    vector< vector<int> > g(n);
    rep(i, n){
        int u, k;
        cin >> u >> k;
        --u;
        rep(j, k){
            int v;
            cin >> v;
            g[u].emplace_back(--v);
        }
    }

    int t = 1;
    vector<int> d(n, -1), f(n, -1);
    rep(i, n){
        if(d[i] < 0){
            dfs(i, t, d, f, g);
        }
    }

    rep(i, n){
        cout << i + 1 << " " << d[i] << " " << f[i] << endl;
    }

    return 0;
}

C++: #include<bits/stdc++.h>
#define REP(i,n) for(int i = 0;i < (n);i++)
#define P pair<int,int>
#define pb push_back
#define mk make_pair
using namespace std;
const int INF = 1e9;

typedef long long ll;

#define MAX_V 10000

struct edge {
    int to;
    int cost;
};


int V;
vector<edge> G[MAX_V];
int d[MAX_V];
int f[MAX_V];
bool mem[MAX_V];
int DFS(int u,int time){
  mem[u] = true;
  d[u] = time;
  REP(i,G[u].size()){
    
    if(!mem[G[u][i].to]){
      time++;
      time = DFS(G[u][i].to,time);
    }
  }
  time++;
  f[u] = time;
  return time;
}


int main(){
  int E,r;
  cin >> V;
 
  REP(i,MAX_V){
    mem[i] = false;
  }
  REP(i,V){
    int k,u;
    cin >> u;
    cin >> k;
    for(int j = 1;j <= k;j++){
      int f,t,c;
      cin >> t;
      c = 1;
      edge e = {t,c};
      G[u].pb(e);
    }
  }
  int t = 1;
  for(int i = 1;i <= V;i++){
    if(!mem[i]){
      t = DFS(i,t);
    }
  }
  for(int i = 1;i <= V;i++){
    cout << i << " " << d[i] << " " << f[i] << endl;;
  }
  
  return 0;
}

C++: #include <cstdio>
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n, M[N][N];
int color[N], d[N], f[N], tt;

//DFS with recursive function
void dfs_visit(int u){
    int v;
    color[u] = GRAY;
    d[u] = ++tt; //first visit time
    for (v=0; v<n; v++){
        if (M[u][v] == 0) continue;
        if (color[v] == WHITE){
            dfs_visit(v);
        }
    }

    color[u] = BLACK;
    f[u] = ++tt; //done visit time
}

void dfs(){
    int u;
    //initialization
    for (u=0; u<n; u++){
        color[u] = WHITE;
    }
    tt = 0;

    for (u=0; u<n; u++){
        if (color[u] == WHITE) dfs_visit(u);
    }
    for (u=0; u<n; u++){
        printf("%d %d %d\n", u+1, d[u], f[u]);
    }
}

int main(){
    int u, v, k, i, j;

    scanf("%d", &n);
    for (i=0; i<n; i++){
        for (j=0; j<n; j++){
            M[i][j] = 0;
        }
    }

    for (i=0; i<n; i++){
        scanf("%d %d", &u, &k);
        u--;
        for (j=0; j<k; j++){
            scanf("%d", &v);
            v--;
            M[u][v] = 1;
        }
    }

    dfs();

    return 0;

}