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: # coding: utf-8
# Your code here!

import sys
read = sys.stdin.read
readline = sys.stdin.readline


def dfs(G, v, d, f, time):
    time += 1
    d[v] = time

    for e in G[v]:
        if d[e] == 0:
            time = dfs(G, e, d, f, time)

    time += 1
    f[v] = time

    return time


def main():
    n = int(readline())

    E = [[]]
    for _ in range(n):
        u,k,*v = map(int, readline().split())
        E.append(v)

    d = [0] * (n+1)
    f = [0] * (n+1)
    time = 0
    
    for i in range(1,n+1):
        if d[i] == 0:
            time = dfs(E, i, d, f, time)
    
    for i in range(1, n+1):
        print(i, d[i], f[i])


if __name__ == "__main__":
    main()

Python: #!/usr/bin/env python3
from enum import Enum


class DFS():
    class Color(Enum):
        WHITE = 0
        GRAY = 1
        BLACK = 2

    def __init__(self, M, n):
        self.M = M
        self.n = n
        self.color = [self.Color.WHITE for _ in range(self.n)]
        self.d, self.f = [-1] * self.n, [-1] * self.n
        self.tt = 0
        self.nt = [0] * self.n

    def next(self, u: int):
        while self.nt[u] < self.n:
            v = self.nt[u]
            self.nt[u] = v + 1
            if self.M[u][v] != 0:
                return v
        return -1

    def dfs_visit(self, r: int):
        S = []                  # list をスタックとして使う
        S.append(r)
        self.color[r] = self.Color.GRAY
        self.tt += 1
        self.d[r] = self.tt
        while len(S) > 0:
            # スタックの一番上（= listの末尾）の値を取得 ※ pop()するとlistからなくなるので[-1]でアクセス
            u = S[-1]
            v = self.next(u)
            if v != -1:
                if self.color[v] == self.Color.WHITE:
                    self.color[v] = self.Color.GRAY
                    self.tt += 1
                    self.d[v] = self.tt
                    S.append(v)
            else:
                S.pop()
                self.color[u] = self.Color.BLACK
                self.tt += 1
                self.f[u] = self.tt

    def dfs(self):
        for u in range(self.n):
            if self.color[u] == self.Color.WHITE:
                self.dfs_visit(u)

        for i in range(self.n):
            print(f'{i+1} {self.d[i]} {self.f[i]}')


def main():
    n = int(input())
    M = [[0] * n for _ in range(n)]

    for i in range(n):
        line = input()
        inputs = [int(x) for x in line.split(' ')]
        u = inputs.pop(0)
        u -= 1                  # 0 オリジンへ変換
        _ = inputs.pop(0)       # k （使わない...）
        for v in inputs:
            v -= 1              # 0 オリジンへ変換
            M[u][v] = 1

    DFS(M, n).dfs()


if __name__ == '__main__':
    main()

Python: n = int(input())
V = [[] for _ in range(n)]
for i in range(n):
    data = list(map(int, input().split(" ")))
    V[i] = data[2:]

answer = [[None, None] for _ in range(n)]

counter = 1


def dfs(v):
    global counter
    if answer[v][0] == None:
        answer[v][0] = counter
        counter += 1
        # ノードの子供の管理
        for e in V[v]:
            dfs(e-1)
        answer[v][1] = counter
        counter += 1


for i in range(len(answer)):
    if answer[i][0] == None:
        dfs(i)

for i in range(len(answer)):
    print(str(i+1) + " " + " ".join(map(str, answer[i])))

Python: def depth_search(i, adj, d, f, t):
    if d[i-1]:
        return t
    d[i-1] = t
    t += 1                                          
    for v in adj[i-1]:
        t = depth_search(v, adj, d, f, t)
    f[i-1] = t                                      
    t += 1
    return t

n = int(input())
adj = [list(map(int, input().split()))[2:] for _ in range(n)] 

d = [0] * n
f = [0] * n

t = 1
for i in range(n):
    if d[i] == 0:
        t = depth_search(i+1, adj, d, f, t)

for i, df in enumerate(zip(d, f)):
    print(i + 1, *df)

Python: def MAIN():
    n = int(input())
    ans = [[i, 0, 0] for i in range((n + 1))]
    G = [[] for _ in range((n + 1))]
    for _ in range(n):
        u, k, *v = map(int, input().split())
        G[u] = v
    cnt = 1
    def dfs(u):
        nonlocal ans
        if ans[u][1] != 0:
            return
        nonlocal cnt
        ans[u][1] = cnt
        cnt += 1
        for v in G[u]:
            dfs(v)
        ans[u][2] = cnt
        cnt += 1
    for i in range(1, n + 1):
        if ans[i][1] == 0:
            dfs(i)
    for i in range(1, n + 1):
        print(*ans[i])
MAIN()

Python: # 深さ優先探索（行きがけ、帰りがけ）
import sys
input = sys.stdin.readline
from collections import deque

# グラフの作成(無向グラフでは#を消す)
N = int(input())
graph = [deque([]) for _ in range(N + 1)]
for _ in range(N):
    u, k, * v = [int(x) for x in input().split()] # uは頂点番号、kは隣接頂点の個数
    v.sort()
    for i in v:
        graph[u].append(i)
        # graph[i].append(u) # 無向グラフ

time = 0
arrive_time = [-1] * (N + 1) # 到着時刻
finish_time = [-1] * (N + 1) # 探索終了時刻

# 深さ優先探索
def dfs(v):
    global time
    time += 1
    stack = [v]
    arrive_time[v] = time
    while stack:
        v = stack[-1]
        if graph[v]:
            w = graph[v].popleft()
            if arrive_time[w] < 0:
                time += 1
                arrive_time[w] = time
                stack.append(w) 
        else:
            time += 1
            finish_time[v] = time
            stack.pop()          
    return [arrive_time, finish_time]

# 孤立している頂点対策
for i in range(N):
    if arrive_time[i + 1] < 0:
        ans = dfs(i + 1)

# 頂点番号、到着時刻、終了時刻
for j in range(N):
    temp = [j + 1, ans[0][j + 1], ans[1][j + 1]]
    print(* temp)