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>
#include <stack>

using namespace std;

const static 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];

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

    return 0;
}

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];

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;

  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;

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

  return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<stack>
#include<string>
#define NIL -1

using namespace std;

const int white=0;
const int gray=1;
const int black=2;
const int maxn=1110;
int G[maxn][maxn];
int color[maxn];
int ne[maxn],d[maxn],f[maxn];
int n,tt; 

int next(int u)
{
	for(int v=ne[u];v<n;v++){
		ne[u]=v+1;
		if(G[u][v])return v;
	}
	return NIL;
}

void dfs(int r)
{
	if(r>=n||color[r]!=white)return;
	stack<int> st;
	memset(ne,0,sizeof(ne));
	st.push(r);
	color[r]=gray;
	d[r]=++tt;
	while(!st.empty()){
		int u=st.top();
		int v=next(u);
		if(v!=NIL){
			if(color[v]==white){
				color[v]=gray;
				d[v]=++tt;
				st.push(v);
			}
		}else{
			color[u]=black;
			st.pop();
			f[u]=++tt;
		}
	}
	while(color[r+1]!=white)r++;
	dfs(r+1);
}

int main()
{
	memset(color,white,sizeof(white));
	memset(G,0,sizeof(G));
	memset(f,0,sizeof(f));
	memset(d,0,sizeof(d));
	int u,k,v;
	cin>>n;
	//邻接矩阵存图 
	for(int i=0;i<n;i++){
		cin>>u>>k;
		u--;
		for(int j=0;j<k;j++){
			cin>>v;
			v--;
			G[u][v]=1;
		}
	}
	tt=0;
	dfs(0);
	for(int i=0;i<n;i++){
		cout<<i+1<<' '<<d[i]<<' '<<f[i]<<endl;
	}
	return 0;
}

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

int A[MAX][MAX] = {0};
int color[MAX] = {0};
int f[MAX] = {0};
int d[MAX] = {0};
int time = 0;
int n;
stack<int> S;

int next(int u)
{
	for(int i=0; i<n; i++)
	{
		if(A[u][i])
		{
			if(color[i] == WHITE)
				return i;
		}
	}
	return -1;
}

void dfs(int u)
{
	S.push(u);
	color[u] = GRAY;
	d[u] = ++time;
	while(!S.empty())
	{
		int v = S.top();
		int x = next(v);
		if(x!=-1 && x!= v)
		{
			color[x] = GRAY;
			S.push(x);
			d[x] = ++time;
		}
		else
		{
			S.pop();
			color[v] = BLACK;
			f[v] = ++time;
		}
	}
}

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

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

	return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <string>
#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 d[N], color[N],f[N],tt;

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

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

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