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 <cstdio>
#include <iostream>
#include <cmath>
#include <ctype.h>
#include <string>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <map>
#include <queue>
#include <utility>
#include <vector>
#include <set>
#include <list>
#include <cstring>
#include <stack>

using namespace std;

#define mod 1000000007

int n;
int d[101], v[101];
int graph[101][101] = {};

int solve(int k, int cnt)
{
	d[k] = cnt;
	int nowcnt = cnt;
	for(int i = 0; i < n; i++){
		if(d[i] < 0 && graph[k][i] > 0) nowcnt = solve(i, nowcnt + 1);
	}
	return v[k] = nowcnt + 1;
}

int main()
{
	cin >> n;
	for(int i = 0; i < n; i++){
		d[i] = -1;
		v[i] = -1;
		int u, k;
		cin >> u >> k;
		u--;
		for(int j = 0; j < k; j++){
			int v;
			cin >> v;
			v--;
			graph[u][v] = 1;
		}
	}
	int nowcnt = 1;
	for(int i = 0; i < n; i++){
		if(d[i] < 0) nowcnt = solve(i, nowcnt) + 1;
	}
	for(int i = 0; i < n; i++){
		cout << i + 1 << " " << d[i] << " " << v[i] << endl;
	}
}

C++: #include <iostream>
#include <queue>
#include <vector>
#include <algorithm>

using namespace std;

int curTime = 1;
void dfs(int cur, const vector<vector<bool> >& a, vector<int>& d, vector<int>& f, vector<bool>& visited){
  visited[cur] = true;
  d[cur] = curTime;
  curTime++;
  // cerr << "visiting [" << cur << "], time = " << curTime << endl;

  for(int dst = 1; dst <= a.size(); dst++){
    if(a[cur][dst] && !visited[dst]) {// cur????????¶??????????????????????????????
      dfs(dst, a, d, f, visited);
    }
  }
  f[cur] = curTime;
  curTime++;
  return;
}

int main(){
  int n;
  cin >> n;
  vector<vector<bool> > a(n+1, vector<bool>(n+1, false));
  for(int i = 1; i <= n; i++){
    int u;
    cin >> u;
    int k;
    cin >> k;
    for(int j = 0; j < k; j++){
      int v;
      cin >> v;
      a[i][v] = true;
    }
  }

  vector<bool> visited(n+1, false);
  vector<int> d(n+1), f(n+1);

  for(int i = 1; i <= n; i++){
    if(!visited[i]){
      dfs(i, a, d, f, visited);
    }
  }

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

C++: #include<iostream>
#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]==0){continue;}
        if(color[v]==WHITE){dfs_visit(v);}
    }
    color[u]=BLACK;
    f[u]=++tt;
}

void dfs(){
    int u;
    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",u+1,d[u],f[u]);
    }
}

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

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

const int MAX = 100;
int n;
int G[MAX + 1][MAX + 1];
int bt[MAX + 1], et[MAX + 1];
int states[MAX + 1];
int t = 0;

void dfs(int id) {
  if (states[id] == 1) return;
  states[id] = 1;
  bt[id] = ++t;
  for (int i = 0; i < n; i++) {
    if (G[id][i] == 1 && states[i] == 0) {
      dfs(i);
    }
  }
  et[id] = ++t;
}

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

  cin >> n;

  int u, v, k;

  for (int i = 0; i < n; i++) {
    states[i] = 0;
    for (int j = 0; j < n; j++) {
      G[i][j] = 0;
    }
  }

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

  for (int i = 0; i < n; i++) {
    dfs(i);
  }

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

  return 0;
}

C++: #include<bits/stdc++.h>

using namespace std;

typedef vector<int> vec;
typedef vector<vec> Graph;

Graph G(110);
int T,In[110],Out[110];
bool used[110];

void dfs(int x)
{
	used[x]=true;
	In[x]=++T;
	for(int i=0;i<G[x].size();i++)
		if(!used[G[x][i]])
			dfs(G[x][i]);
	Out[x]=++T;
}

int main()
{
	int n;
	scanf("%d",&n);
	for(int i=0;i<n;i++)
	{
		int u,t;
		scanf("%d%d",&u,&t);
		for(int j=0;j<t;j++)
		{
			int v;
			scanf("%d",&v);
			G[u].push_back(v);
		}
	}
	memset(used,false,sizeof(used));
	T=0;
	dfs(1);
	for(int i=1;i<=n;i++)
		printf("%d %d %d\n",i,In[i],Out[i]);
	return 0;
}

C++: #include <stdio.h>
#include <stdlib.h>

int stack[100], sp;
int start[100], end[100];
int ti;

void dfs(int , int **);
void visit(int , int **, int *);
int pop();
void push(int);

int main(){

  int i, j;
  int n, u , k;
  int **a;

  scanf("%d", &n);

  a = (int **)malloc(sizeof(int *) * n);

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

    a[i] = (int *)malloc(sizeof(int) * k + 1);
    a[i][k] = -1;

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

  }

  dfs(n, a);

  for(i = 0; i < n; i++){
    printf("%d %d ", i + 1, start[i]);
    printf("%d\n", end[i]);
  }


  return 0;
}

void dfs(int n, int **a){

  int i;
  int color[100];

  for(i = 0; i < n; i++){
    color[i] = 0;
  }

  for(i = 0; i < n; i++){
    if(color[i] == 0) visit(i, a, color);
  }

}

void visit(int u, int **a, int *c){

  int i;
  int v;

  c[u] = 1;
  start[u] = ++ti;

  for(i = 0; a[u][i] != -1; i++){
    v = a[u][i] - 1;
    if(c[v] == 0) visit(v, a, c); 

  }  

  c[u] = 2;
  end[u] = ++ti;

}

int pop(){

  sp--;

  return stack[sp];
}


void push(int d){

  stack[sp] = d;

  sp++;

}