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 <vector>
using namespace std;

int t = 0;
vector<int> edge[101];
bool back_edge[101];

pair<int, int> visit_time[101];

void dfs(int cur)
{
    t += 1;
    visit_time[cur].first = t;

    for (int i = 0; i < (int)edge[cur].size(); i++) // cur から行ける頂点について
    {
        if (back_edge[edge[cur][i]] == false)
        {
            back_edge[edge[cur][i]] = true;
            dfs(edge[cur][i]);
        }
    }

    t += 1;
    visit_time[cur].second = t;
}

int main()
{
    int n;
    cin >> n;

    for (int i = 0; i < n; i++)
    {
        int u, k;
        cin >> u >> k;
        back_edge[u] = false;
        for (int j = 0; j < k; j++)
        {
            int v;
            cin >> v;
            edge[u].push_back(v);
        }
    }

    for (int i = 1; i < n; i++)
        if (back_edge[i] == false)
        {
            back_edge[i] = true;
            dfs(i);
        }

    for (int i = 1; i <= n; i++)
    {
        cout << i
             << " " << visit_time[i].first
             << " " << visit_time[i].second << endl;
    }
}

C++: #include<stdio.h>
#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; //最初の訪問
    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;//訪問の完了
}

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

    tt=0;

    for(u=0; u<n; u++){
        //未訪問のuを始点として深さ優先探索
        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;
}

C++: #include <stdio.h>

int A[101][101];
int ans[101][3];
int an = 1;

int serch(int a[101][101], int  ni, int n){
  int  j;
  
  for(j=0; j<n; j++){
    if(A[ni][j] == 1){
      judge(j, 1);
      serch(A, j, n);
    }
  }
  judge(ni, 2);
}

int judge(int i, int j){
  if(ans[i][j] == 0){
    ans[i][j] = an;
    an++;
  }
}

int  main(){
  int i, j, k, n, x, y;
  
  scanf("%d", &n);
  
  for(i=0; i<n; i++){
    for(j=0; j<n; j++)
      A[i][j] = 0;
    ans[i][0] = i+1;
  }
  
  for(i=0; i<n; i++){
    scanf("%d %d", &x, &y);
    for(j=0; j<y; j++){
      scanf("%d", &k);
      A[i][k-1] = 1;
    }
  }
  
  judge(0, 1);
  
  for(i=0; i<n; i++){
    if(A[0][i] == 1){
      judge(i, 1);
      serch(A, i, n);
    }
  }
  judge(0, 2);
  
  for(i=0; i<n; i++){
    for(j=0; j<3; j++){
      if(j>0)
        printf(" ");
      printf("%d", ans[i][j]);
    }
    printf("\n");
  }
  
  return 0;
}

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

const int MAX_N = 100;
int to[MAX_N][MAX_N];
int ans[MAX_N][2];
bool visited[MAX_N];
int depth = 1;

void dfs(int x) {
  if (ans[x][0] == -1) ans[x][0] = depth++;
  for (int i=0; to[x][i] != -1 && !visited[to[x][i]]; i++) {
    dfs(to[x][i]);
  }
  if (ans[x][1] == -1) ans[x][1] = depth++;
}

int main() {
  int N;
  cin >> N;
  for (int i=0; i<N; i++) {
    for (int j=0; j<N; j++) {
      to[i][j] = -1;
    }
    ans[i][0] = ans[i][1] = -1;
    visited[i] = false;
  }
  for (int i=0; i<N; i++) {
    int tmp, n;
    cin >> tmp >> n;
    for (int j=0; j<n; j++) {
      int t;
      cin >> t; t--;
      to[i][j] = t;
    }
  }

  visited[0] = true;
  dfs(0);
  for (int i=0; i<N; i++) {
    cout << i+1 << " " << ans[i][0] << " " << ans[i][1] << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<string>
#include<sstream>
#include<cmath>
#include<numeric>
#include<map>
#include<stack>
#include<queue>
using namespace std;
int inf = 1000000000;

class Graph{
public:
  int v;
  int ftime = -1;
  int ltime = -1;
  vector<int> e;
};
vector<Graph> g;
int cnt = 0;
void dfs(int pos){
  if( g[pos].ftime != -1 ) return;
  cnt++;
  g[pos].ftime = cnt;
  for(int i=0; i<g[pos].e.size(); i++){
    dfs(g[pos].e[i]);
  }
  cnt++;
  g[pos].ltime = cnt;
}

int main(void) {

  int n;
  cin >> n;
  g.resize(n);
  int u, k;
  for(int i=0; i<n; i++){
    cin >> u >> k;
    u--;
    g[u].v = u;
    g[u].e.resize(k);
    for(int j=0; j<k; j++){
      cin >> g[u].e[j];
      g[u].e[j]--;
    }
    sort(g[u].e.begin(), g[u].e.end());
  }

  dfs(0);
  for(int i=0; i<n; i++){
    cout << g[i].v + 1 << " " << g[i].ftime << " " << g[i].ltime << endl;
  }



  return 0;
}

// EOF

C++: #include<cstdio>
#include<stack>
using namespace std;
static const int MAXN=101;
static const int INF=(1<<21);
int main(){
	int m[MAXN][MAXN],n,u,k,v,i,j,first[MAXN]={},second[MAXN]={},l,c=1,o;
	stack<int> s;
	bool used[MAXN]={};
	scanf("%d",&n);
	for(i=1;i<n+1;i++){
		for(j=1;j<n+1;j++){
			m[i][j]=INF;
		}
	}
	for(i=0;i<n;i++){
		scanf("%d %d",&u,&k);
		for(j=0;j<k;j++){
			scanf("%d",&v);
			m[u][v]=1;
		}
	}
	s.push(1);
	used[1]=true;
	while(!s.empty()){
		l=s.top();
		if(first[l]==0){
			first[l]=c;
		}
		o=0;
		for(i=1;i<n+1;i++){
			if(m[l][i]==1&&used[i]==false){
				s.push(i);
				o=1;
				used[i]=true;
				break;
			}
		}
		c++;
		if(o==0){
			second[l]=c;
			s.pop();
		}
	}
	for(i=1;i<n+1;i++){
		printf("%d %d %d\n",i,first[i],second[i]);
	}
	return 0;
}

C++: #include<bits/stdc++.h>
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 ){
        scanf("%d %d",&u,&k);
        u--;
        for( int j = 0; j < k; ++j ){
            scanf("%d",&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;
}