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

edge=[[0 for i2 in range(n)]for i1 in range(n)]

#??£??\???????????????

for i in range(n):
    for j in range(adj[i][1]):
        edge[i][adj[i][j+2]-1]=1


time=1
discover=[0 for i in range(n)]
final=[0 for i in range(n)]
stack=[]

def dfs(id,time):
    for i in range(n):
        c=0
        if edge[id][i]==1 and discover[i]==0:
            stack.append(id)
            discover[i]=time
            c+=1
            #print(discover,final,i,stack)
            dfs(i,time+1)
        else:
            pass
    if c==0:
        if len(stack)>0:
            if final[id]==0:
                final[id] = time
                #print("back",discover,final,id,stack)
                dfs(stack.pop(), time + 1)
            else:
                #print("back", discover, final, id, stack)
                dfs(stack.pop(),time)

discover[0]=time
stack.append(0)
dfs(0,time+1)


for i in range(n):
    if discover[i]==0:
        discover[i]=final[0]+1
        stack.append(i)
        dfs(i,final[0]+2)
        break

for i in range(n):
    print(i+1,discover[i],final[i])

Python: # 深さ優先探索 Depth first search: DFS


def dfs(u):
    global time
    color[u - 1] = 0
    time += 1
    d[u - 1] = time
    for v in range(1, n + 1):
        if A[u - 1][v - 1] == 1 and color[v - 1] == -1:
            dfs(v)
    color[u - 1] = 1
    time += 1
    f[u - 1] = time


n = int(input())
A = [[0 for i in range(n)] for i in range(n)]
for i in range(n):
    dat = [int(j) for j in input().split()]
    for j in range(dat[1]):
        A[dat[0] - 1][dat[2 + j] - 1] = 1

color = [-1 for i in range(n)]
d = [-1 for i in range(n)]
f = [-1 for i in range(n)]
time = 0
for i in range(n):
    if color[i] == -1:
        dfs(i+1)

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

Python: n = int(input())
graph = [[] for _ in range(n)]
for i in range(n):
    in_list = list(map(int, input().split()))
    u = in_list[0]
    graph[u - 1] = in_list[2:]

d = [0 for _ in range(n)]
f = [0 for _ in range(n)]
time = 0

def dfs(now, prev, graph, d, f):
    if d[now] != 0:
        return d, f
    global time
    time += 1
    d[now] = time
    if not graph[now]:
        f[now] = time + 1
        time += 1
        return
    for k in graph[now]:
        if k - 1 == prev or d[k-1] !=0:
            continue
        dfs(k - 1, now, graph, d, f)
    else:
        time += 1
        f[now] = time
    return d, f



for i in range(n):
    d, f = dfs(i, 0, graph, d, f)
    print(i+1, d[i], f[i])

Python: class Node(object):
    def __init__(self, V):
        self.V = V
        self.find_time = 0
        self.finish_time = 0
        self.is_finded = False
  
  
n = int(input())
nodes = [0] * 101
for i in range(n):
    data = input().split()
    V = list(map(int, data[2:]))
    V.sort(reverse = True)
    nodes[int(data[0])] = Node(V)
  
find_q = []
find_q.append(1)
cnt = 1
q_size = len(find_q)
while q_size != 0:
    #print(find_q)
    node = nodes[find_q[q_size -1]]
  
    if node.is_finded == False:
        node.find_time = cnt
        cnt += 1
        node.is_finded = True
        if len(node.V) == 0:
            node.finish_time = cnt
            cnt += 1
            find_q.pop()
            q_size = len(find_q)
        else:
            for x in node.V:
                if nodes[x].is_finded == False:
                    if x in find_q:
                        find_q.remove(x)
                    if nodes[x].finish_time == 0: 
                        find_q.append(x)
            q_size = len(find_q)
  
    else:   #node is finded
        node.finish_time = cnt
        cnt += 1
        find_q.pop()
        q_size = len(find_q)
        continue
  
for i in range(1, n+1):
    if not isinstance(nodes[i], int):
        print(i, nodes[i].find_time, nodes[i].finish_time)

Python: import sys


def dfs(u):
    global time
    color[u] = "GRAY"
    time += 1
    d[u] = time
    for v in range(n):
        if M[u][v] and color[v] == "WHITE":
            dfs(v)
    color[u] = "BLACK"
    time += 1
    f[u] = time


if __name__ == "__main__":
    n = int(sys.stdin.readline())
    color = ["WHITE"] * n
    time = 0
    d = [-1] * n
    f = [-1] * n
    M = [[0] * n for i in range(n)]
    for inp in sys.stdin.readlines():
        inp = list(map(int, inp.split()))
        for i in inp[2:]:
            M[inp[0]-1][i-1] = 1
    for i in range(n):
        if d[i] == -1:
            dfs(i)
    for i in range(n):
        print(i+1, d[i], f[i])