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()
}

Python: n = int(input())
A = [[False for _ in range(n)] for _ in range(n)]
for _ in range(n):
    tmp = list(map(int, input().split()))
    for i in range(tmp[1]):
        A[tmp[0]-1][tmp[i+2]-1] = True

WHITE = 0
GRAY = 1
BLACK = 2
color = [WHITE for _ in range(n)]
d = [0 for _ in range(n)]
f = [0 for _ in range(n)]
time = 1

def dfs(u):
    global dfs_color, d, f, time
    color[u] = GRAY
    d[u] += time
    time += 1
    for v in range(n):
        if A[u][v]:
            if color[v] == WHITE:
                dfs(v)
        else:
            continue
    color[u] = BLACK
    f[u] = time
    time += 1 

for u in range(n):
    if color[u] == WHITE:
        dfs(u)

for i in range(n):
    print(str(i+1) + ' ' + str(d[i]) + ' ' + str(f[i]) )

Python: n = int(input())
graph = {}
for _ in range(n):
  i = list(map(int,input().split()))
  graph[i[0]] = i[2:]

first = {i:0 for i in range(1,n+1)}
last = {i:0 for i in range(1,n+1)}
seen = set()
time = 1

def dfs(v):
  global time
  seen.add(v)
  first[v] = time
  time += 1
  for nxt in graph[v]:
    if nxt in seen:
      continue
    dfs(nxt)
  last[v] = time
  time += 1

for i in range(1,n+1):
  if i not in seen:
    dfs(i)
  
for i in range(1,n+1):
  print(i, first[i], last[i])

Python: import sys

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

time = 0

def dfs(u, adj, d, f, sumi):
    global time
    time += 1
    d[u] = time

    for v in adj[u]:
        if v not in sumi:
            dfs(v, adj, d, f, sumi)
        sumi.add(v)

    time += 1

    f[u] = time


def solve():
    n = int(input())
    adj = [None] * n

    for i in range(n):
        u, k, *vs = [int(j) - 1 for j in input().split()]
        # debug(vs, locals())
        adj[u] = vs

    # debug(adj, locals())
    
    d = [0] * n
    f = [0] * n
    sumi = {0}

    dfs(0, adj, d, f, sumi)

    for i in range(n):
        print(i, d[i], f[i])

    pass

if __name__ == '__main__':
    solve()

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys

WHITE, GRAY, BLACK = 0, 1, 2


def generate_adj(v_info):
    for v_detail in v_info:
        v_adj_list = v_detail[2:]
        assert len(v_adj_list) == int(v_detail[1])
        for each in v_adj_list:
            init_adj_matrix[int(v_detail[0]) - 1][int(each) - 1] = 1
    return init_adj_matrix


def graph_dfs(start_node_index):
    # init the first node
    v_index = int(start_node_index)
    vertex_visit_stack.append(v_index)
    vertex_color_list[v_index] = GRAY
    time = 1
    vertex_d_time[v_index] += time
    # init end
    while len(vertex_visit_stack) > 1:
        current_vertex = vertex_visit_stack[-1]
        try:
            next_vertex = adj_matrix[current_vertex - 1].index(1) + 1
        except ValueError:
            # print('err')
            vertex_visit_stack.pop()
            vertex_color_list[current_vertex] = BLACK
            time += 1
            vertex_f_time[current_vertex] += time
        else:
            if vertex_color_list[next_vertex] == WHITE:
                # print('w2g', current_vertex, next_vertex, vertex_color_list[next_vertex])
                vertex_color_list[next_vertex] = GRAY
                time += 1
                vertex_d_time[next_vertex] += time
                vertex_visit_stack.append(next_vertex)
                # node A to B only visit once
                adj_matrix[current_vertex - 1][next_vertex - 1] = 0
            else:
                time += 1
                vertex_f_time[current_vertex] += time
                vertex_visit_stack.pop()
    return None


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertex_num = int(_input[0])
    vertex_info = list(map(lambda x: x.split(), _input[1:]))
    init_adj_matrix = [[0] * vertex_num for _ in range(vertex_num)]
    # assert len(vertex_info) == vertex_num

    vertex_visit_stack = [-1]
    vertex_color_list = [WHITE] * (vertex_num + 1)
    vertex_d_time, vertex_f_time = [0] * (vertex_num + 1), [0] * (vertex_num + 1)
    adj_matrix = generate_adj(vertex_info)

    graph_dfs(start_node_index=1)
    for i in range(vertex_num):
        print(i + 1, vertex_d_time[i + 1], vertex_f_time[i + 1])

Python: n = int(input())

graph = []
for _ in range(n):
    tmp = list(map(int, input().split()))
    if tmp[1] == 0:
        graph.append([])
    else:
        graph.append(tmp[2:])
#print(graph)

seen = [0]*n
to_do = []
in_list = [0]*n
out_list = [0]*n
count = 0

def dfs(v):
    #print(v)
    global count
    if seen[v] == 0:
        seen[v] = 1
        count += 1
        in_list[v] = count
        to_do = graph[v]
        #print(in_list)
        #print(to_do)
        if len(to_do) > 0:
            for i in to_do:
                dfs(i-1)
        count += 1
        out_list[v] = count
        #print(out_list)
while True:
    if 0 in seen:
        k = seen.index(0)
        dfs(k)
    else:
        break

for i in range(n):
    print("{} {} {}".format(i+1,in_list[i],out_list[i]))