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++: //1908-1930 22m
#include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
#include<cstring>
#include<vector>
#include<stack>
using namespace std;
#define INT(x) int x; scanf("%d",&x)
#define INPUT(x) scanf("%d",&x)
#define REP1(x,n) for(int x = 0; x < n; x++)
#define REP2(x,s,e) for(int x = s; x <= e; x++)
#define BR printf("\n")
#define INF 2000000000
#define FIND 0
#define END 1

int TimeStump[100][2] = {};//find,end
vector<int> V[100];
stack<int> S;
int time_ = 1;

void DFS(int i){
    if (TimeStump[i][FIND] != 0) return;
    S.push(i);
    TimeStump[i][0] = time_;
    time_++;
    
    REP1(k,V[i].size()){
        if (TimeStump[V[i][k]][FIND] == 0){DFS(V[i][k]);}
    }
    
    S.pop();
    TimeStump[i][1] = time_;
    time_++;
}

int main(){
    INT(N);
    REP1(i,N){
        int from,n;
        scanf("%d %d",&from,&n);
        REP1(j,n){
            INT(to);
            V[i].push_back(to - 1);
        }
    }
    
    REP1(i,N) DFS(i);
    
    REP1(i,N) printf("%d %d %d\n",i+1,TimeStump[i][0],TimeStump[i][1]);
    return 0;
}

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

int n,p=0,side[101][101],startTime[101],endTime[101],v[101];

void dfs(int x){
  if(!v[x]) {
    v[x]++; startTime[x]=++p;
	for (int i =1; i<n+1; i++) {
      if(side[x][i]) {
        dfs(i);
      }
    }
	endTime[x]=++p;
  }
}

int main(){
	int a,b,c;
	cin>>n;
	for (int i =0; i<n; i++) {
      cin>> a >> b;
      for (int i =0; i<b; i++) {
        cin >> c;
        side[a][c]++;
      }
    }
  
  for (int i =1; i<n+1; i++) {
    if(!v[i]) dfs(i);
  }
  for (int i =1; i<n+1; i++) {
    cout << i << ' ' << startTime[i] << ' ' << endTime[i] << endl;    
  }
}

C++: #include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<stack>
#include<vector>
using namespace std;
#define MAX 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

int d[MAX],f[MAX];
int color[MAX];
vector<int> V[MAX];
int tt=0,n=0;
stack<int> S;

void dfs(int x){
  S.push(x);
  d[x]=++tt;
  color[x]=GRAY;
  while(!S.empty()){
    int u=S.top();
    int next=-1;
    for(int i=0;i<V[u].size();i++){
      if(color[V[u][i]]==WHITE){
        next=V[u][i]; break;
      }
    }
    if(next==-1){
      color[u]=BLACK;
      S.pop();
      f[u]=++tt;
      continue;
    }
    color[next]=GRAY;
    S.push(next);
    d[next]=++tt;
  }
}

void begindfs(){
  for(int i=0;i<n;i++){
    if(color[i]==WHITE) dfs(i);
  }
}

int main(){
  int u,v,j;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>u>>v;
    u--;
    for(int k=0;k<v;k++){
      cin>>j;
      j--;
      V[u].push_back(j);
    }
  }
  begindfs();
  for(int i=0;i<n;i++){
    cout<<i+1;
    printf(" %d %d\n",d[i],f[i]);
  }

}

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;

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

// u?????£??\??????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;
}

// ?????????????????¨????????±???????????¢?´¢
void dfs_visit(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() {
  // ?????????
  for (int i = 0; i < N; i++) {
    color[i] = WHITE;
    nt[i] = 0;
  }
  tt = 0;

  // ????¨???????u????§??????¨????????±???????????¢?´¢
  for (int u = 0; u < n; u++) {
    if (color[u] == WHITE) dfs_visit(u);
  }
  for (int i = 0; i < n; i++) {
    cout << i + 1 << " " << d[i] << " " << f[i] << endl;
  }
}

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

  cin >> n;
  for (i = 0; i < n; i++) {
    for (j = 0; j < n; j++) M[i][j] = 0;
  }

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

  dfs();

  return 0;
}

C++: #include <bits/stdc++.h>
#define r(i,a,n) for(int i=a;i<n;i++)
using namespace std;
int a[101][101],start[101],end[101],n,p=0,v[101];
void dfs(int u){
	if(!v[u]){v[u]++;
	start[u]=++p;
	r(i,1,n+1)if(a[u][i])dfs(i);
	end[u]=++p;}
}
int main(){
	int q,qq,qqq;
	cin>>n;
	r(i,0,n){cin>>q>>qq;
		r(i,0,qq){cin>>qqq;
			a[q][qqq]++;
		}
	}
	dfs(1);
	r(i,1,n+1)cout<<i<<' '<<start[i]<<' '<<end[i]<<endl;
}

C++: #include<iostream>
using namespace std;
int visit[101],d[101],f[101],t;
int n,M[101][101];
static const int WHITE=0;
static const int GRAY=1;

void dfs(int u){
  visit[u]=GRAY;
  d[u]=++t;
  for(int v=0;v<n;v++){
    if(M[u][v]==0) continue;
    if(visit[v]==WHITE) dfs(v);
  }
  f[u]=++t;
}

int main(){
  int u,v,k;
  cin>>n;
  
  for(int i=0;i<n;i++){
    cin>>u>>k;
    u--;
    for(int j=0;j<k;j++){
      cin>>v;
      v--;
      M[u][v]=1;
    }
  }
  
  for(int i=0;i<n;i++){
    if(visit[i]==WHITE) dfs(i);
  }

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