Go: package main

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

type TimeRecord struct {
	discoverTime int
	finishTime   int
}

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

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

	timeRecordMap := make([]TimeRecord, n)
	childrenMap := make([][]int, n)
	for i := 1; i <= n; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		timeRecordMap[node-1] = TimeRecord{-1, -1}

		childNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		childrenMap[node-1] = make([]int, childNum)
		for j := 0; j < childNum; j++ {
			child, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			childrenMap[node-1][j] = child
		}
	}

	timer := 1
	for {
		startNode := findStartNode(childrenMap, timeRecordMap)
		if startNode > 0 {
			visit(startNode, &timer, childrenMap, timeRecordMap)
		} else {
			break
		}
	}
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

func findStartNode(childrenMap [][]int, timeRecordMap []TimeRecord) int {
	x := -1
	for node, timeRecord := range timeRecordMap {
		if timeRecord.discoverTime < 0 {
			x = node + 1
			break
		}
	}
	if x < 0 {
		return -1
	}

	found := false
	i := 0
	for i < len(childrenMap) {
		children := childrenMap[i]
		for j := 0; j < len(children); j++ {
			if children[j] == x {
				x = j + 1
				found = true
				break
			}
		}
		if found {
			i = 0
		} else {
			i++
		}
	}
	return x
}

func visit(currentNode int, timer *int, childrenMap [][]int, timeRecordMap []TimeRecord) {
	if timeRecordMap[currentNode-1].discoverTime > 0 {
		return
	}
	children := childrenMap[currentNode-1]
	timeRecordMap[currentNode-1] = TimeRecord{*timer, timeRecordMap[currentNode-1].finishTime}
	(*timer)++
	for i := 0; i < len(children); i++ {
		visit(children[i], timer, childrenMap, timeRecordMap)
	}
	timeRecordMap[currentNode-1] = TimeRecord{timeRecordMap[currentNode-1].discoverTime, *timer}
	(*timer)++
}

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

Python: # ALDS_11_B - 深さ優先探索
import sys

n = int(input())
e = [None] * n
for _ in range(n):
    u, k, *v = map(int, sys.stdin.readline().strip().split())
    e[u - 1] = [i - 1 for i in v]


S = []  # stack
time = 0
t_in = [0] * n
t_out = [0] * n
fp = [False] * n  # foot print  訪問の記録


def dfs(u):
    global time

    S.append(u)
    time += 1
    t_in[u] = time
    fp[u] = True

    while S:
        u = S[-1]

        v = None
        for i in e[u]:
            if fp[i] is False:
                v = i
                break

        time += 1
        if v is not None:
            S.append(v)
            t_in[v] = time
            fp[v] = True

        else:
            v = S.pop()
            t_out[v] = time


while False in fp:
    dfs(fp.index(False))

for i in range(n):
    print(f'{i + 1} {t_in[i]} {t_out[i]}')

Python: from sys import stdin
readline=stdin.readline

#入力
n=int(readline())
m=n+1
u,k,v=[0]*m,[0]*m,[0]*m
for i in range(1,m):
    u[i],k[i],*v[i]=map(int,readline().split())

d=[0]*m
f=[0]*m
flags=[False]*m
t=0
def dfs(now):
    global t
    t+=1
    d[now]=t
    flags[now]=True
    for nex in v[now]:
        if flags[nex]==False:
            dfs(nex)
    t+=1
    f[now]=t
now=1
while True:
    dfs(now)
    for i in range(1,m):
        if flags[i]==False:
            now=i
            break
    else:
        break

for i in range(1,m):
    print(i,d[i],f[i])

Python: n=0
t=1
def adjacent_matrix():
    global n
    n=int(input())
    v=[]
    array=[]
    for i in range(n):
        zero=[0 for i in range(n)]
        a=list(map(int,input().split()))
        a=a[2:]
        for j in a:
            zero[j-1]=1
        array.append(zero)
    return array
def dfs(array,i,d,f):
    global t
    if i == n:
        return
    else:
        if(d[i] == 0):
            d[i] = t
            t += 1
            for (j,x) in enumerate(array[i]):
                if x == 1:
                    dfs(array,j,d,f)
            f[i] = t
            t += 1
    return dfs(array,i+1,d,f)


def main():
    array=adjacent_matrix()
    print()
    d=[0 for i in range(n)]
    f=[0 for i in range(n)]
    dfs(array,0,d,f)
    for i in range(n):
        print("{} {} {}".format(i+1,d[i],f[i]))

if __name__ == "__main__":
    main()

Python: #coding:utf-8
from copy import deepcopy

n = int(input())
c = ["white" for i in range(n)]
d = [0 for i in range(n)]
f = [0 for i in range(n)]
S = []
class DFS:
    def __init__(self, key, color="white",nex=None):
        self.color = color
        self.nex = nex
        self.key = key

objListCopy = [DFS(i+1) for i in range(n)]
for i in range(n):
    data = list(map(int,input().split()))
    times = data[1]
    obj = objListCopy[i]
    for j in range(times):
        index = data[2+j] - 1
        nextobj = DFS(index+1)
        obj.nex = nextobj
        obj = obj.nex


time = 1
objList = objListCopy[:]
def check(first,time):
    obj = objList[first]
    c[first] = "gray"
    d[first] = time
    f[first] = time
    S.append(first+1)
    
    while S != []:
        index = S[-1] - 1
        u = objList[index]
        v = u.nex
        
        time += 1
        if v != None and c[v.key - 1] == "white":
            objList[index] = v
            index = v.key - 1
            v = objList[index]
            c[v.key-1] = "gray"
            d[index] = time
            S.append(v.key)

        elif v != None and c[v.key - 1] == "black" and v.nex != None:
            objList[index] = v
            time -= 1
            
        else:
            S.pop()
            c[u.key-1] = "black"
            f[index] = time
    return time


for i in range(n):
    if f[i] == 0:
        objList = deepcopy(objListCopy)
        time = check(i,time) + 1
        

k = 1
for i,j in zip(d,f):
    print(k,i,j)
    k += 1

Python: def solve(v, g, ans, time):
    if ans[v]["found"] != 10**9:
        return time
    time += 1
    # print(v + 1, time, file=sys.stderr)
    ans[v]["found"] = time
    for a in g[v]:
        time = solve(a, g, ans, time)
    time += 1
    # print(v + 1, time, file=sys.stderr)
    ans[v]["complete"] = time
    return time


def resolve():
    n = int(input())
    V = [list(map(int, input().split())) for _ in range(n)]
    g = [[] for _ in range(n)]
    for v, k, *a in V:
        v -= 1
        for ai in a:
            ai -= 1
            g[v].append(ai)
    ans = [{"found": 10**9, "complete": -1} for _ in range(n)]
    time = solve(0, g, ans, 0)
    for i in range(n):
        if ans[i]["found"] == 10**9:
            solve(i, g, ans, time)
        print(i + 1, ans[i]["found"], ans[i]["complete"])


resolve()

Python: def dfs_visit(u):
    global dfs_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:
            dfs_visit(v)
    color[u] = BLACK
    f[u] += t
    t += 1

n = int(input())
M = [[False for i in range(n)] for j in range(n)]
WHITE = 0
GRAY = 1
BLACK = 2
color = [WHITE for i in range(n)]
d = [0 for i in range(n)]
f = [0 for i in range(n)]
t = 1
for i in range(n):
        a = list(map(int, input().split()))
        for j in range(a[1]):
            M[a[0] - 1][a[j + 2] - 1] = True
for u in range(n):
    if color[u] == WHITE:
        dfs_visit(u)
for u in range(n):
    print(str(u + 1), str(d[u]), str(f[u]), sep = " ")