Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

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

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

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveDfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

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

Python: from collections import deque


def dfs(root):
    global time
    stack.append(root)
    color[root] = 'gray'
    arrive[root] = time
    time += 1

    while len(stack) > 0:
        node = stack[-1]
        for next in range(n):
            if adjMat[node][next] == 1:
                if color[next] == 'white':
                    color[next] = 'gray'
                    arrive[next] = time
                    time += 1
                    stack.append(next)
                    break
        # In case there in no adjacent node whose color is white
        color[node] = 'black'
        finish[node] = time
        time += 1
        stack.pop()


n = int(input())

adjMat = [[0] * n for _ in range(n)]
color = ['white'] * n
stack = deque()
arrive = [0] * n
finish = [0] * n
time = 1

for _ in range(n):
    adj = list(map(int, input().split()))
    i = adj[0]
    v = adj[2:]
    for j in v:
        adjMat[i - 1][j - 1] = 1

for root in range(n):
    if color[root] == 'white':
        dfs(root)

for i in range(n):
    out = ''
    out += '{} {} {}'.format(i + 1, arrive[i], finish[i])
    print(out)

Python: # -*- coding: utf-8 -*-
"""
Created on Sat Apr  6 11:36:14 2019

@author: Yamazaki Kenichi
"""

n = int(input())
A = [[]]
A = A + [list(map(int,input().split())) for i in range(n)]

def dfs(k):
    global counta
    for i in range(A[k][1]):
        if T[A[k][i+2]][0] == -1:
            T[A[k][i+2]][0] = 0
            T[A[k][i+2]][1] = counta
            counta += 1
            dfs(A[k][i+2])
    T[k][2] = counta
    T[k][0] = 1
    counta += 1

T = [[-1,-1,-1] for i in range(n+1)]
counta = 1
for i in range(1,n+1):
    if T[i][0] == -1:
        T[A[i][0]][0],T[A[i][0]][1] = 0, counta
        counta += 1
        dfs(i)

for i in range(1,n+1):
    print(" ".join(map(str,[i,T[i][1],T[i][2]])))

Python: N = int(input())
Adj = [[0 for i in range(N)] for j in range(N)]

for i in range(N):
    u = list(map(int, input().split()))
    if u[1] > 0:
        for k in u[2: 2+u[1]]:
            Adj[u[0] - 1][k - 1] = 1
            
            
color = [0] * N #1: visited, 0: not visited, 2: completed
s = [0] * N # start
f = [0] * N # finish

time = 0

def DFS(u):
    global time
    color[u-1] = 1
    time += 1
    s[u-1] = time
    
    for i in range(1, N+1):
        if Adj[u-1][i-1] == 1 and color[i-1] == 0:
            DFS(i)
            
    color[u-1] = 2
    time += 1
    f[u-1] = time

for i in range(1, N+1):
    if color[i-1] == 0:
        DFS(i)
        
for i in range(N):
    print('{} {} {}'.format(i+1, s[i], f[i]))

Python: # ??????????????????????£?????????????deque??????????????????
from collections import deque


class Node:
    def __init__(self, no, childs):
        self.no = no
        self.childs = childs
        self.find_time = None
        self.finish_time = None
        self.visit = False


def get_node_index(nodes, no):
    for i in range(len(nodes)):
        if nodes[i].no == no:
            return i


def get_unvisited(visited, childs):

    if childs is None: return None

    for i in range(len(childs)):
        if childs[i] not in visited:
            return childs[i]


"""
Main??????????????????
"""
# Node??°?????????
N = int(input())

# Node??????????????????????????????
nodes = []

# Node??????????¨????
for i in range(N):
    j = list(map(int, input().split())) # ??\??????????§£
    no = j[0]                           # Node??????????????? [2 2 1 4] ->2?????????
    childNum = j[1]
    if childNum != 0:
        childs = j[2:]                  # ??????????´?????????? [2 2 1 4] ->[1,4]?????????
    else:
        childs = []                     # ??????????´?????????? [2 2 1 4] ->[1,4]?????????
    nodes.append(Node(no, childs))


# ??±???????????¢?´¢(DFS)?????????
total_time = 1   # ??¢?´¢??????
stack = deque() # ??¢?´¢???????´?????´?????????????
stack.appendleft(1)
no = get_node_index(nodes, stack[0])  # ?????¨??¢?´¢???????´???????
nodes[no].find_time = total_time
visited = []    # ??¢?´¢??????????´?????´??????????

while stack:
    no = get_node_index(nodes, stack[0])  # ?????¨??¢?´¢???????´???????
    total_time += 1  # ??¢?´¢??????+1
    visited.append(stack[0])              # ??¢?´¢??????????????????????´?
    # ?????¢?´¢???????´??????????
    unvisited = get_unvisited(visited, nodes[no].childs)
    if unvisited is not None:
        # ?????¢?´¢???????´??????????????????????????????¢?´¢????´????????????§??????????????????????????????????´???§????????´????????¢?´¢?????\?????????????????????
        if nodes[unvisited-1].visit is False:
            nodes[unvisited-1].visit = True
            stack.appendleft(unvisited)
            nodes[unvisited-1].find_time = total_time
    else:
        stack.popleft()
        nodes[no].finish_time = total_time



#??¨?????????
for i in range(N):
    print("{0} {1} {2}".format(nodes[i].no, nodes[i].find_time, nodes[i].finish_time))

Python: def visit(u):
    global visit_color, d, f, t
    color[u] = GRAY
    d[u] += t
    t += 1
    for v in range(n):
        if (M[u][v] == 0):
            continue
        if (color[v] == WHITE):
            visit(v)
    color[u] = BLACK
    f[u] = t
    t += 1

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

WHITE = 0
GRAY = 1
BLACK = 2
color, d, f = [WHITE for i in range(n)]
t = 1
for u in range(n):
    if (color[u] == WHITE):
        visit(u)
for u in range(n):
    print(str(u+1), str(d[u]), str(f[u]), sep = " ")