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 typing import List


def alds_1_11a():
    n = int(input())
    for i in range(n):
        u, k, *v = map(int, input().split())
        a = [0] * n
        for i_v in v:
            index_v = i_v - 1
            a[index_v] = 1
        print(*a)
    return


def print_matrices_list(matrices_list):
    for index_row in range(len(matrices_list)):
        print(*matrices_list[index_row])
    return


# def depth_first_search(u, stack, color, d):
#     stack.append(u)
#     color[u] = 1
#     while len(stack) != 0:
#     pass


def accept_adjacency_list() -> List[List[int]]:
    n = int(input())
    adjancy_list = []
    for i in range(n):
        list_u = list(map(int, input().split()))
        adjancy_list.append(list_u)
    return adjancy_list


def adjacency_list2adjacency_matrices(adj_list: List[List[int]]) -> List[List[int]]:
    adjancy_matrices = []
    n = len(adj_list)
    for list_u_i in adj_list:
        id_u, degree_k, *list_v = list_u_i
        list_row = [0] * n
        for v_i in list_v:
            list_row[v_i - 1] = 1
        adjancy_matrices.append(list_row)
    return adjancy_matrices


def dfs(adj_mat):
    n = len(adj_mat)
    list_colors = [0] * n  # 0:white, 1:gray, 2:black
    time = 0
    d = [0] * n  # 最初に訪問した頂点uの発見時刻
    f = [0] * n  # uの隣接リストを調べ終えた完了時刻

    for u in range(n):
        if list_colors[u] == 0:
            list_colors, time, d, f = dfs_visit(u, list_colors, adj_mat, d, f, time)

    for u in range(n):
        print(u + 1, d[u], f[u])
    return


def dfs_visit(u: int, list_colors: list, adj_mat: list, d: list, f: list, time: int):
    list_colors[u] = 1  # uを訪問
    time += 1
    d[u] = time
    for v in range(len(list_colors)):  # v:次に探索する場所
        if adj_mat[u][v] == 0:  # uからvに行く辺がないなら次へ
            continue
        if list_colors[v] == 0:  # uからvに道があるかつ行ったことがないなら行く。
            list_colors, time, d, f = dfs_visit(
                u=v, list_colors=list_colors, adj_mat=adj_mat, d=d, f=f, time=time
            )
    list_colors[u] = 2
    time += 1
    f[u] = time
    return list_colors, time, d, f


if __name__ == "__main__":
    # init
    adjacency_list = accept_adjacency_list()
    adjacency_matirces = adjacency_list2adjacency_matrices(adj_list=adjacency_list)

    dfs(adj_mat=adjacency_matirces)

Python: n = int(input())
ukv = [[0, 0, 0]] + [list(map(int, input().split())) for _ in range(n)]

stack = []
visited = []
time = 0
d = [0] * (n + 1)
f = [0] * (n + 1)
for i in range(1, n + 1):
    if i not in visited:
        stack.append(i)
        visited.append(i)
        time += 1
        d[i] = time

        while stack:
            s = stack[-1]
            k = ukv[s][1]
            if k == 0:
                stack.pop()
                time += 1
                f[s] = time
            else:
                ukv[s][1] -= 1
                v = ukv[s].pop(2)
                if v not in visited:
                    stack.append(v)
                    visited.append(v)
                    time += 1
                    d[v] = time

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

Python:    #depth first
N=int(input())
V=[]
a=[0]
for i in range(N):
    V.append([int(i) for i in input().split()])
    w=V[i][2:]
    w.sort()
    V[i]=V[i][:2]+w
    a.append(0)
V=sorted(V,key=lambda x:x[0])
c=1
t=1
i=0
r=[1]
a[1]=1
p=[[1,t]]
q=[]
while t<N*2-1:
    j=2
    while t<N*2-1 and j-2<V[i][1] and V[i][1]>0 and a[V[i][j]]==1:
        j+=1
    t+=1
    if j-2<V[i][1]:
        a[V[i][j]]=1
        c+=1
        r.append(V[i][j])
        p.append([V[i][j],t])
        i=V[i][j]-1
    else:
        q.append(p[-1]+[t])
#end time immediately case?
        r.pop(-1)
        p.pop(-1)
        i=r[-1]-1
       # print(q)
q.append([1,1,N*2])
q=sorted(q,key=lambda x:x[0])
for i in range(N):
    for j in range(3):
        q[i][j]=str(q[i][j])
    print(" ".join(q[i]))

Python: def DFS(G):
    ans = [0] + [[0,0,0] for _ in range(len(G))]
    def main(G,i):
        ans[0] += 1
        ans[i] = [i, ans[0], ans[0]]
        for j in sorted(G[i-1][2:]):
            if ans[j][0]==0: main(G,j)
        ans[0] += 1
        ans[i][2] = ans[0]
    main(G,1)
    return ans[1:]


if __name__=='__main__':
    n = int(input())
    G = [list(map(int,input().split())) for _ in range(n)]
    for out in DFS(G): print(*out)

Python: n = int(input())
graph = [[] for _ in range(n)]

global time
global visited 
global f_time 
global e_time 

time = 1
visited = [0 for _ in range(n)]
f_time = [0 for _ in range(n)]
e_time = [0 for _ in range(n)]

def input_graph(n):
  for _ in range(n):
    node_id, num, *v = list(map(int, input().split()))
    for i in range(num):
      graph[node_id-1].append(v[i]-1)

def dfs(node_id):
  global time
  f_time[node_id] = time
  time += 1

  for ad_node in graph[node_id]:
    if visited[ad_node] == 1:
      continue
    visited[ad_node] = 1
    dfs(ad_node)

  e_time[node_id] = time
  time += 1



if __name__ == "__main__":
  input_graph(n)
  for i in range(n):
    if visited[i] == 1:
      continue
    visited[i] = 1
    dfs(i)

  for i, (f, e) in enumerate(zip(f_time, e_time)):
    print(i+1, f, e)

Python: # -*- coding: utf-8 -*-
import sys
INF=10**18
MOD=10**9+7
def input(): return sys.stdin.readline().rstrip()


c=0
def main():
    N=int(input())
    edge=[[] for _ in range(N)]
    for i in range(N):
        l=list(map(lambda x:int(x)-1,input().split()))
        for x in l[2:]:
            edge[i].append(x)
    d=[-1]*N
    f=[-1]*N
    used=[False]*N
    def dfs(v):
        global c
        used[v]=True
        d[v]=c
        for nv in edge[v]:
            if not used[nv]:
                c+=1
                dfs(nv)
        c+=1
        f[v]=c
    global c
    while not all(used):
        for i in range(N):
            if not used[i]:
                c+=1
                dfs(i)

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

if __name__ == '__main__':
    main()