Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

type TimeRecord struct {
	discoverTime int
	finishTime   int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	timeRecordMap := make([]TimeRecord, n)
	childrenMap := make([][]int, n)
	for i := 1; i <= n; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		timeRecordMap[node-1] = TimeRecord{-1, -1}

		childNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		childrenMap[node-1] = make([]int, childNum)
		for j := 0; j < childNum; j++ {
			child, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			childrenMap[node-1][j] = child
		}
	}

	// TODO: always start with 1?
	timer := 1
	visit(1, &timer, childrenMap, timeRecordMap)
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

func visit(currentNode int, timer *int, childrenMap [][]int, timeRecordMap []TimeRecord) {
	if timeRecordMap[currentNode-1].discoverTime > 0 {
		return
	}
	children := childrenMap[currentNode-1]
	timeRecordMap[currentNode-1] = TimeRecord{*timer, timeRecordMap[currentNode-1].finishTime}
	(*timer)++
	for i := 0; i < len(children); i++ {
		visit(children[i], timer, childrenMap, timeRecordMap)
	}
	timeRecordMap[currentNode-1] = TimeRecord{timeRecordMap[currentNode-1].discoverTime, *timer}
	(*timer)++
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

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, tt;
int M[N][N], color[N], d[N], f[N], 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 {
		   color[u] = BLACK;
		   S.pop();
		   f[u] = ++tt;
		}
	} 
}


void dfs() {
	for(int i = 0; i < n; i++) {
	     color[i] = WHITE;
	}
	tt = 0;
		
	dfs_visit(0);
	
	for(int i = 0; i < n; i++) {
		cout << i + 1 << " " << d[i] << " " << f[i] << endl;	
	}
}

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

C++: #if 0
time: 15min
using e[] as a indicator to find whether a node has been searched.						
#endif
#include <iostream>
#include <queue>

using namespace std;

int p[100+10][100+10];
int D[100+10],e[100+10],f[100+10];
int n,a,b,c,t;

void dfs(int cur){
	D[cur] = 1;
	t += 1;
	for (int i=1; i<=n; i++){
		if (p[cur][i]>0 && !D[i]){
			f[i] = t+1;
			dfs(i);
		}
	}
	t += 1;
	e[cur] = t;
}

int main(){
	cin >> n;
	for (int i=1; i<=n; i++){
		cin >> a >> b;
		for (int j=1; j<=b; j++){
			cin >> c;
			p[a][c] = 1;
		}
	}
	dfs(1);
	f[1] = 1;
	for (int i=1; i<=n; i++){
		cout << i << ' ' << f[i] << ' ' << e[i] << endl;
	}
}

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;
}