Go: package main

import (
	"fmt"
)

func main() {
	var n int
	fmt.Scan(&n)
	g := make([][]int, n+1)
	for i := 0; i < n; i++ {
		var u,k int
		fmt.Scan(&u)
		fmt.Scan(&k)
		g[u] = make([]int, k)
		for j := 0; j < k; j++ {
			fmt.Scan(&g[u][j])
		}
	}

	d := make([]int, n+1)
	f := make([]int, n+1)
	t := 1
	for i := 1; i <= n; i++ {
		t = dfs(&g, &d, &f, i, t)
	}

	for i := 1; i <= n; i++ {
		fmt.Printf("%d %d %d\n", i, d[i], f[i])
	}
}

func dfs(g *[][]int, d *[]int, f *[]int, id int, t int) int {
	if (*d)[id] > 0 {
		return t
	}
	(*d)[id] = t
	t += 1
	for i := 0; i < len((*g)[id]); i++ {
		t = dfs(g, d, f, (*g)[id][i], t)
	}
	(*f)[id] = t
	return t+1
}

Python: n=int(input())
a=[[0 for i in range(n)]for j in range(n)]
for i in range(n):
    v=list(input().split())
    for j in range(len(v)):
        v[j]=int(v[j])
    x=2
    for k in range(v[1]):
        a[i][v[x+k]-1]=1
#print(a)

stack=[]
v=[]
d=[0]*n
f=[0]*n
t=1

while len(v)<n:
    for i in range(n):
        if i+1 not in v:
            stack.append(i+1)
            d[i]=t
            break
        else: pass
        
    while len(stack)!=0:
        for i in range(n):
            if a[stack[-1]-1][i]==1 and stack[-1]-1!=i and i+1 not in v:
                stack.append(i+1)
                a[stack[-1]-1][i]==0
                t+=1
                d[i]=t
            elif i==n-1:
                t+=1
                f[stack[-1]-1]=t
                v.append(stack.pop())
            else: pass
            # print("stack ",stack)
            #print("v ",v)
#print("d=",d," f=",f)
for i in range(n):
    print(i+1,d[i],f[i])

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

import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = "BEFORE", "IN", "AFTER"


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(v_init):
    global time
    # init the first node of overall graph iterations(times >= 1)
    vertex_visit_stack.append(v_init)
    vertex_status_list[v_init] = VISITED_IN_STACK
    vertex_d_time[v_init] += time
    # init end
    while len(vertex_visit_stack) > 1:
        time += 1
        current_vertex = vertex_visit_stack[-1]
        next_vertex = get_next_vertex(node=current_vertex)
        # print(current_vertex, next_vertex, vertex_status_list, vertex_visit_stack)
        if next_vertex and vertex_status_list[next_vertex] is UNVISITED:
            vertex_status_list[next_vertex] = VISITED_IN_STACK
            vertex_d_time[next_vertex] += time
            vertex_visit_stack.append(next_vertex)

        else:
            other_vertex = get_next_vertex(current_vertex)
            if other_vertex:
                graph_dfs(other_vertex)
            else:
                vertex_visit_stack.pop()
                vertex_status_list[current_vertex] = POPPED_OUT
                vertex_f_time[current_vertex] += time

    return None


def get_next_vertex(node):
    for j in range(vertex_num):
        if adj_matrix[int(node) - 1][j]:
            adj_matrix[int(node) - 1][j] = 0
            return j + 1


def dfs_start():
    global time
    for i in range(vertex_num):
        if vertex_status_list[i + 1] == UNVISITED:
            # print('round', i + 1)
            graph_dfs(v_init=i + 1)
            time += 1


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_status_list = [UNVISITED] * vertex_num
    vertex_status_list.insert(0, 'NULL')
    vertex_d_time, vertex_f_time = [[0] * (vertex_num + 1) for _ in range(2)]
    adj_matrix = generate_adj(vertex_info)

    time = 1
    dfs_start()

    for k in range(vertex_num):
        print(k + 1, vertex_d_time[k + 1], vertex_f_time[k + 1])

Python: n = int(input())
a = [[] for i in range(n)]

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

d = [0] * n
f = [0] * n
isDiscovered = [False] * n
time_stamp = 0

def dfs(x):
    global time_stamp
    isDiscovered [x] = True
    time_stamp += 1
    d[x] = time_stamp
    for i in a[x]:
        if not isDiscovered[i]:
            dfs(i)
    time_stamp += 1
    f[x] = time_stamp
 
for i in range(n):
    if not isDiscovered[i]:
        dfs(i)
 
for i in range(n):
    print(i+1, d[i], f[i])
 
for i in range(n):
    if not isDiscovered[i]:
        dfs(i)
 
for i in range(n):
    print(i+1, d[i], f[i])

Python: 
# ??±???????????¢?´¢(Depth First Search)

def DFS(i, n):
    for j in range(n):
        if A[i][j] == 1 and d[j] == 0:
            time = time + 1
            d[j] = time
            DFS(j)
    time = time + 1
    f[i] = time

n = int(raw_input())
A = [0] * n
for i in range(n):
    A[i] = [0] * n

for i in range(n):
    value = map(int, raw_input().split())
    u = value[0] - 1
    k = value[1]
    nodes = value[2:]
    for i in range(k):
        v = nodes[i] - 1
        A[u][v] = 1

d = [0] * n
f = [0] * n
time = 1
d[0] = time
DFS(0, n)

for i in range(n):
    print(str(i + 1) + " " + str(d[0]) + " " + str(f[0]))

Python: n=int(input())
#V[u]=[k,[v],d,f]
V=[[0,[],0,0]]
for i in range(n):
    v=[int(i) for i in input().split(" ")]
    u=v.pop(0)
    k=v.pop(0)
    v.sort()
    V.append([k,v,0,0])


def is_finished(Id):
    k=V[Id][0]
    v=V[Id][1]
    for i in range(k):
        if V[v[i]][2]==0:
            return v[i]
    return -1

time=1

while time<=2*n:
 for i in range(1,n+1):
     if V[i][2]==0:
         cur=i
         log=[i]
         break

 while len(log)>0:
    if V[cur][2]==0:
        V[cur][2]=time
        time+=1


    x=is_finished(cur)
    if x!=-1:
        cur=x
        log.append(cur)
    else:
        try:
            log.pop(-1)
            V[cur][3]=time
            time+=1
            if V[cur][3]==V[cur][2]:
                time+=1
                V[cur][3]+=1

            cur=log[-1]
        except:
            pass
for i in range(1,n+1):
    print(i,V[i][2],V[i][3])

Python: def dfs_init(color,n,dq):
	for i in range(n):
		color[i] = "White"

def next(u):
	for v in range(list_next[u],n):
		list_next[u] = v+1
		if list_m[u][v]:
			return v


def dfs_visit(u,color,dq,tt):
	tt = tt
	dq.append(u)
	color[u] = "Gray"
	list_d[u] = tt + 1
	tt += 1
	while dq:
		u = dq[-1]
		v = next(u)
		if v != None:
			if color[v] == "White":
				color[v] = "Gray"
				list_d[v] = tt + 1
				tt += 1
				dq.append(v)
		else:
			dq.pop()
			color[u] = "Black"
			list_f[u] = tt + 1
			tt += 1
	return tt

from collections import deque
n = int(input())
list_m = [[0]*n for i in range(n)]
list_next = [0] * n
list_color = [0] * n
list_d = [0]*n
list_f = [0]*n
dq = deque([])

for i in range(n):
	a,b,*args = map(int, input().split())
	for num in args:
		list_m[a-1][num-1] = 1
tt = 0
list_num = [i+1 for i in range(n)]
dfs_init(list_color,n,dq)
for u in range(n):
	if list_color[u] == "White":
		tt = dfs_visit(u,list_color,dq,tt)

for i in range(n):
	print(list_num[i], list_d[i] ,list_f[i])

Python: def dfs(v, cnt):
    D[v] = cnt
    cnt += 1
    for c in edge[v]:
        if D[c] == -1:
            cnt = dfs(c, cnt)
    F[v] = cnt
    cnt += 1
    return cnt
 
 
V = int(input())
edge = [[] for _ in range(V)]
for _ in range(V):
    u, _, *v = map(lambda x: int(x)-1, input().split())
    edge[u] = sorted(v)
D, F = [-1] * V, [-1] * V
c = 1
for i in range(V):
    if D[i] == -1:
        c = dfs(i, c)
for i, (d, f) in enumerate(zip(D, F)):
    print(i+1, d, f)