Go: package main

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

/***************************************************************
stackによる深さ優先探索を実装する。
***************************************************************/

const (
	N     = 100
	WHITE = 0
	GRAY  = 1
	BLACK = 2
)

var (
	n            int
	Adj          [N][N]int
	statusColor  [N]int
	discoverTime [N]int
	finishTime   [N]int
	clock        int
	nt           [N]int
)

/***************************************************************
Stackの定義:
- field
	container: ノードの格納されたスライス
	sp: スタックポインタ
- method
	size(): スタックに積まれているノードの個数を返す
	top(): スタックの一番上に積まれているノードを返す
	isEmpty(): スタックが空かどうかを返す
	pop(): スタックの要素をポップし削除する
	push(): スタックに要素を積む
***************************************************************/

type Stack struct {
	container []int
	sp        int
}

func (s *Stack) size() int {
	return len(s.container)
}

func (s *Stack) top() int {
	return s.container[s.sp]
}

func (s *Stack) isEmpty() bool {
	return s.sp == 0
}

func (s *Stack) pop() int {
	_pop := func() {
		s.container = s.container[:len(s.container)-1]
	}
	defer _pop()
	if s.isEmpty() {
		panic("There is no elements in stack!")
	}
	s.sp--
	return s.container[s.sp]
}

func (s *Stack) push(n int) {
	s.sp++
	s.container[s.sp] = n
}

func next(u int) int {
	for v := nt[u]; v < n; v++ {
		nt[u] = v + 1
		if Adj[u][v] == 1 {
			return v
		}
	}
	return -1
}

func _DFS(target int) {
	for i := 0; i < n; i++ {
		nt[i] = 0
	}
	stack := new(Stack)
	stack.container = make([]int, N+1)
	stack.push(target)
	statusColor[target] = GRAY
	clock++
	discoverTime[target] = clock
	for !stack.isEmpty() {
		u := stack.top()
		v := next(u)
		if v != -1 {
			if statusColor[v] == WHITE {
				statusColor[v] = GRAY
				clock++
				discoverTime[v] = clock
				stack.push(v)
			}
		} else {
			stack.pop()
			statusColor[u] = BLACK
			clock++
			finishTime[u] = clock
		}
	}
}

func DFS() {
	for i := 0; i < n; i++ {
		statusColor[i] = WHITE
		nt[i] = 0
	}
	clock = 0
	for i := 0; i < n; i++ {
		if statusColor[i] == WHITE {
			_DFS(i)
		}
	}
	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", i+1, discoverTime[i], finishTime[i])
	}
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	scanner.Scan()
	n, _ = strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		for j := 0; j < n; j++ {
			Adj[i][j] = 0
		}
	}
	for i := 0; i < n; i++ {
		scanner.Scan()
		u, _ := strconv.Atoi(scanner.Text())
		scanner.Scan()
		k, _ := strconv.Atoi(scanner.Text())
		u--
		for j := 0; j < k; j++ {
			scanner.Scan()
			v, _ := strconv.Atoi(scanner.Text())
			v--
			Adj[u][v] = 1
		}
	}

	DFS()
}

C++: #include<iostream>
#include<vector>
#include<stack>

const static int MAX = 100;
int G[MAX][MAX];
int nt[MAX];
int n;

int nextNode(int x){
    for(int i = nt[x]; i < n; i++){
	if(G[x][i] == 1){
	    nt[x] = i + 1;
	    return i;
	}
    }
    return -1;
}

int main(void){
    std::stack<int> st;
    int color[MAX], a[MAX], b[MAX];
    int u, k, v, time;

    time = 0;
    std::cin >> n;

    for(int i = 0; i < n; i++){
	color[i] = 0;
    }

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

    for(int i = 0; i < n; i++){
	if(color[i] == 0){
	    st.push(i);
	    color[i] = 1;
	    a[i] = ++time;
	}
	while(!st.empty()){
	    int cur = st.top();
	    int next = nextNode(cur);
	    if(color[next] == 0 && next != -1){
	        st.push(next);
	        color[next] = 1;
	        a[next] = ++time;
	    }
	    if(next == -1){
		st.pop();
		b[cur] = ++time;
	    }
	}
    }

    for(int i = 0; i < n; i++){
        std::cout << i+1 << " " << a[i] << " " << b[i] << std::endl;
    }


    return 0;

}

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

int DFS(bool path[110][110],int begin[],int end[],int v,int n,int t){
    t++;
    begin[v]=t;
    for(int i=0;i<n;i++){
        if(path[v][i]&&begin[i]==0){
            t=DFS(path,begin,end,i,n,t);
        }
    }
    t++;
    end[v]=t;
    return t;
}

int main(void){
    int n,u,k,i,j,x,t;
    bool path[110][110];
    int begin[110],end[110];
    memset(path,0,sizeof(path));
    memset(begin,0,sizeof(begin));
    cin>>n;
    for(i=0;i<n;i++){
        cin>>u>>k;
        u--;
        for(j=0;j<k;j++){
            cin>>x;
            x--;
            path[u][x]=true;
        }
    }
    
    t=0;
    for(i=0;i<n;i++){
        if(begin[i]==0){
            t=DFS(path,begin,end,i,n,t);
        }
    }
    
    for(i=0;i<n;i++){
        cout<<i+1<<" "<<begin[i]<<" "<<end[i]<<endl;
    }
    
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
#define P(x) cout << (x) << endl
#define p(x) cout << (x)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define vv(type, c, m, n, i) vector<vector<type>> c(m, vector<type>(n, i));
#define rep(i,a,n) for(int i=(a), i##_len=(n); i<i##_len; ++i)
#define rrep(i,a,n) for(int i=(a), i##_len=(n); i>i##_len; --i)
#define len(x) ((int)(x).size())
#define mp make_pair
#define eb emplace_back
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long long> vll;
typedef vector<string> vs;
typedef vector<bool> vb;
constexpr int MAX = 101;
enum Color { WHITE = 0, GRAY, BLACK};
int n, tt{0};
vv(int, M, MAX, MAX, 0);
vi color(MAX, 0), d(MAX, 0), f(MAX, 0), nt(MAX, 0);
inline int next(int u) {
	rep(v, nt[u], n) {
		nt[u] = v + 1;
		if(M[u][v]) return v;
	}
	return -1;
}
inline void dfs_visit(int r) {
	deque<int> S;
	S.eb(r);
	color[r] = GRAY;
	d[r] = ++tt;
	int u, v;
	while(!S.empty()) {
		u = S.back();
		v = next(u);
		if(v != -1) {
			if(color[v] == WHITE) {
				color[v] = GRAY;
				d[v] = ++tt;
				S.eb(v);
			}
		} else {
			S.pop_back();
			color[u] = BLACK;
			f[u] = ++tt;
		}
	}
}
inline void dfs() {
	tt = 0;
	rep(u, 0, n) {
		if(color[u] == WHITE) dfs_visit(u);
	}
	rep(i, 0, n) {
		cout << i + 1 << " " << d[i] << " " << f[i] << endl;
	}
}
int main() {
	cin >> n;
	int u, k, v;
	rep(i, 0, n) {
		cin >> u >> k;
		--u;
		rep(j, 0, k) {
			cin >> v;
			M[u][--v] = 1;
		}
	}
	dfs();
	return 0;
}

C++: #include <stdio.h>

const int WHITE = -1;
const int GRAY = -2;
const int BLACK = -3;

int g[101][101], time1[101], time2[101], visit[101];
int n, u, k, m;
int t;

void dfs(int root)
{
	time1[root] = ++t;
 visit[root] = GRAY;
	for (int i = 1; i <= n; i++)
	{
		if (g[root][i] != -1 && visit[i] == WHITE)
		{
			visit[i] = GRAY;
			dfs(i);
		}
	}
	visit[root] = BLACK;
	time2[root] = ++t;
}

int main()
{
	scanf("%d", &n);
	for (int i = 1; i <= n; i++)
		visit[i] = WHITE;

	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= n; j++)
			g[i][j] = -1;

	for (int i = 1; i <= n; i++)
	{
		scanf("%d%d", &u, &k);
		for (int j = 0; j < k; j++)
		{
			scanf("%d", &m);
			g[u][m] = 1;
		}
	}
	dfs(1);
	for (int i = 1; i <= n; i++)
	{
		printf("%d %d %d\n", i, time1[i], time2[i]);
	}

	return 0;
}