Go: package main

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

var N int
var A [][]int
var t int
var color, d, f []int

const (
	WHITE = iota
	GRAY
	BLACK
)

func dfsVisit(u int) {
	color[u] = GRAY
	t ++
	d[u] = t
	for v:=0; v<N; v++ {
		if A[u][v] == 0 {
			continue
		}
		if color[v] == WHITE {
			dfsVisit(v)
		}
	}
	color[u] = BLACK
	t++
	f[u] = t
}

func dfs() {
	for u:=0; u<N; u++ {
		if color[u] == WHITE {
			dfsVisit(u)
		}
	}
	for u:=0; u<N; u++{
		fmt.Printf("%d %d %d\n", u+1, d[u], f[u])
	}
}


func nextInt(scanner *bufio.Scanner) int {
	scanner.Scan()
	num, _ := strconv.Atoi(scanner.Text())
	return num
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	N = nextInt(scanner)
	color = make([]int, N)
	d = make([]int, N)
	f = make([]int, N)
	A = make([][]int, N)
	for i:=0; i<N; i++{
		A[i] = make([]int, N)
	}
	for i:=0; i<N; i++{
		index := nextInt(scanner) - 1
		cnt := nextInt(scanner)
		for j:=0; j<cnt; j++ {
			v := nextInt(scanner) - 1
			A[index][v] = 1
		}
	}
	dfs()
}

C++: #include<bits/stdc++.h>
#include<string.h>
#define MAX 101
#define WHITE -1
#define GRAY 2
#define BLACK 1
using namespace std;

int G[MAX][MAX]={},d[MAX]={},f[MAX]={},color[MAX]={},times=0,Adj[MAX]={};

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

void visit(int u,int n){
    color[u]=GRAY;
    d[u]=++times;
    int v=1;
    while(v<=n){
        if(G[u][v]>0){
            if(color[v]==WHITE)visit(v,n);
        }
        v++;
    }
    color[u]=BLACK;
    f[u]=++times;
}

void dfs(int V[],int n){
    int u;
    for(u=1;u<=n;u++){
        color[u]=WHITE;
    }
    times =0;
    for(u=1;u<=n;u++){
        if(color[u]==WHITE)visit(u,n);
    }
}

int main(){
  int n,i,k,j,A,B,V[MAX]={};
  cin>>n;
  for(i=0;i<MAX;i++){
    for(j=0;j<MAX;j++){
        G[i][j]=-1;
    }
  }
  for(i=0;i<n;i++){
    cin>>A>>k;
    for(j=0;j<k;j++){
      cin>>B;
      G[A][B]=1;
    }
  }
  dfs(V,n);
  print(n);
}

C++: 
/*
Problem

Category
DFS

URL:
http://judge.u-aizu.ac.jp/onlinejudge/submission.jsp#submit/ALDS1_11_B

考察:


Date: 2020/04/14
*/

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long

/* ==== declarations ====== */
// functions
void solve();
void getInput();

// global variables
int n;
int counter = 1;
vector<vector<int>> ALL;
// vector<int> isVisited;
vector<int> d;
vector<int> f;
vector<int> visited;

/* ======================== */

signed main(){
    getInput();
    solve();
    return 0;
}

void getInput() {
    cin>>n;
    d.resize(n);
    f.resize(n);
    for(int i=0; i<n; ++i) {
        int u, k;
        cin>>u>>k;
        u--;
        vector<int> AL;
        for(int j=0; j<k; ++j) {
            int v;
            cin>>v;
            AL.push_back(--v);
        }
        ALL.push_back(AL);
    }
}

void dfs(int v) {    
    d[v] = counter++;
    visited.push_back(v);
    for(auto u: ALL[v]) {
        if (find(visited.begin(), visited.end(), u) == visited.end()) {
            dfs(u);
        }
    }
    f[v] = counter++;
}


void solve() {
    for(int u=0; u<n; ++u) {
        if (find(visited.begin(), visited.end(), u) == visited.end()) {
            dfs(u);
        }
    }
    for(int i=0; i<n; ++i ) {
        cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;
    }
}

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

struct Node{
    bool comp;
    int starttime, endtime;
};

int Time = 1;

void setTime(queue<int> q[], stack<int> t, Node l[]){
    if(Time == 1){
        t.push(1);
        l[0].starttime = Time++;
        setTime(q, t, l);
    }

    if(t.size() == 0){
        return;
    }

    int index = t.top() -1;

    // if(l[index].comp){
    //     cout << index << endl;
    //     t.pop();
    //     setTime(q, t, l);
    // }

    if(q[index].size() == 0){
        t.pop();
        l[index].endtime = Time++;
        l[index].comp = true;
        setTime(q, t, l);
    } else {
        int val = q[index].front();
        q[index].pop();

        if(l[val - 1].comp) setTime(q, t, l);
        else{
            t.push(val);
            l[val - 1].starttime = Time++;
            setTime(q, t, l);
        }
    }

}

int main(){
    int n, v, k, l;
    cin >> n;
    queue<int> q[n];
    stack<int > timetable;
    Node timelist[n];
    for(int i=0; i<n; i++){
        cin >> v >> k;
        v--;
        timelist[i].comp = false;
        for(int j=0; j<k; j++){
            cin >> l;
            q[v].push(l);
        }
    }

    setTime(q, timetable, timelist);

    for(int i=0; i<n; i++){
        cout << i+1 << " " << timelist[i].starttime << " " << timelist[i].endtime << endl;
    }

    return 0;

}

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

#define MAX 100
static const int WHITE = 0; // not visit
static const int GRAY = 1; // visited
static const int BLACK = 2; // searched

int n;
int M[MAX][MAX] = { 0 };
int color[MAX] = { WHITE };
int d[MAX], f[MAX], tt = 0;
int nt[MAX] = { 0 };

// get vertex next u
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 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;
	}
	return;
}

int main() {
	scanf("%d", &n);

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

	dfs();
	return 0;

}

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

int n, u, k, v;
int d[101], f[101];
pair<int, vector<int> > G[101];

int ti = 1;

void dfs(int id) {
	if (d[id]) return ;
	d[id] = ti ++;

	vector<int>& adj = G[id].second;
	for (int i=0; i<(int)adj.size(); ++i) {
		dfs(adj[i]);
	}
	f[id] = ti ++;
}

int main() {
	cin >> n;
	for (int i=0; i<n; ++i) {
		cin >> u >> k;
		G[u].first = u;
		while (k --) {
			cin >> v;
			G[u].second.push_back(v);
		}
	}
	for (int i=1; i<=n; ++i) {
		dfs(i);
		cout << i << " " << d[i] << " " << f[i] << endl;
	}
	return 0;
}

C++: #include <iostream>
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;
int a[N][N];
int t = 0;
int color[N], check[N], finish[N];
void dfs(int u) {
  t++;
  check[u] = t;
  color[u] = GRAY;
  for (int i = 0; i < n; i++) {
    if (a[u][i] == 0) continue;
    if (color[i] == WHITE) {
      dfs(i);
    }
  }
  color[u] = BLACK;
  finish[u] = ++t;
}

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

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

  for (int i = 0; i < n; i++) {
    color[i] = WHITE;
  }
  for (int i = 0; i < n; i++) {
    if (color[i] == WHITE) {
      dfs(i);
    }
  }
  for (int i = 0; i < n; i++) {
    cout << i + 1 << " " << check[i] << " " << finish[i] << endl;
  }
}