Go: #include <bits/stdc++.h>
using namespace std;
static const int WHITE = 0;
static const int GRAY  = 1;
static const int BLACK = 2;
static const int N     = 100;

int n, tt;
vector<vector<int>> M(N, vector<int>(N));
vector<int> color(N), d(N), f(N);

void dfs_visit(int u) {
  color[u] = GRAY;
  d[u]     = ++tt;
  for (int v = 0; v < n; v++) {
    if (M[u][v] == 0) continue;
    if (color[v] == WHITE) { dfs_visit(v); }
  }
  color[u] = BLACK;
  f[u]     = ++tt;
}

void dfs() {
  tt = 0;

  for (int u = 0; u < n; u++) {
    if (color[u] == WHITE) dfs_visit(u);
  }
  for (int u = 0; u < n; u++) {
    printf("%d %d %d\n", u + 1, d[u], f[u]);
  }
}

int main() {
  int u, v, k;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> u >> k;
    u--;
    for (int j = 0; j < k; j++) {
      cin >> v;
      v--;
      M[u][v] = 1;
    }
  }

  dfs();
}

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

"""
input:
6
1 2 2 3
2 2 3 4
3 1 5
4 1 6
5 1 6
6 0

output:
1 1 12
2 2 11
3 3 8
4 9 10
5 4 7
6 5 6
"""
import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = 0, 1, 2


def generate_adj_matrix(v_info):
    for v_detail in v_info:
        v_index, adj_num, *adj_list = map(int, v_detail)
        # assert len(adj_list) == adj_num
        init_adj_table[v_index].extend(sorted(adj_list, reverse=True))
    return init_adj_table


def graph_dfs(v_init):
    global time

    # init the first node of overall graph iterations(times >= 1)
    stack.append(v_init)
    color[v_init] = VISITED_IN_STACK
    d_time[v_init] += time
    # init end

    while stack:
        current = stack[-1]
        v_table = adj_table[current]
        color[current]=VISITED_IN_STACK
        # if adj is None, current's adj(s) have been all visited
        adj = v_table.pop() if v_table else None

        if adj:
            if color[adj] is UNVISITED:
                color[adj] = VISITED_IN_STACK
                time += 1
                d_time[adj] += time
                stack.append(adj)
        else:
            stack.pop()
            color[current] = POPPED_OUT
            time += 1
            f_time[current] += time

    return None


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


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertices = int(_input[0])
    v_info = map(lambda x: x.split(), _input[1:])
    init_adj_table = tuple([] for _ in range(vertices + 1))
    # assert len(vertex_info) == vertex_num

    # config length = (vertex_num + 1)
    stack = []
    color = [UNVISITED] * (vertices + 1)
    d_time, f_time = ([0] * (vertices + 1) for _ in range(2))

    adj_table = generate_adj_matrix(v_info)
    # timing start from 1
    time = 1
    dfs_start()

    for index, v in enumerate(zip(d_time[1:], f_time[1:]), 1):
        print(index, *v)

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

import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = 0, 1, 2


def generate_adj_matrix(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)
    vertices_visit_stack.append(v_init)
    vertices_status_list[v_init] = VISITED_IN_STACK
    vertices_d_time[v_init] += time
    # init end

    while len(vertices_visit_stack) > 1:
        current_vertex = vertices_visit_stack[-1]
        next_vertex = get_adj_vertices(vertex=current_vertex)

        if next_vertex:
            if vertices_status_list[next_vertex] is UNVISITED:
                vertices_status_list[next_vertex] = VISITED_IN_STACK
                time += 1
                vertices_d_time[next_vertex] += time
                vertices_visit_stack.append(next_vertex)
        else:
            vertices_visit_stack.pop()
            vertices_status_list[current_vertex] = POPPED_OUT
            time += 1
            vertices_f_time[current_vertex] += time

    return None


def get_adj_vertices(vertex):
    index = int(vertex) - 1
    for j in range(vertices_num):
        if adj_matrix[index][j]:
            adj_matrix[index][j] = 0
            return j + 1
    return None


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


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertices_num = int(_input[0])
    vertices_info = list(map(lambda x: x.split(), _input[1:]))
    init_adj_matrix = [[0] * vertices_num for _ in range(vertices_num)]
    # assert len(vertex_info) == vertex_num

    # config length = (vertex_num + 1)
    vertices_visit_stack = [-1]
    vertices_status_list = [UNVISITED] * vertices_num
    vertices_status_list.insert(0, -1)
    vertices_d_time, vertices_f_time = ([0] * (vertices_num + 1) for _ in range(2))

    adj_matrix = generate_adj_matrix(vertices_info)
    # timing start from 1
    time = 1
    dfs_start()
    for k in range(vertices_num):
        print(k + 1, vertices_d_time[k + 1], vertices_f_time[k + 1])

Python: n=int(input())
ne=[[] for _ in range(n+1)]
for _ in range(n):
    u,k,*v=map(int,input().split())
    ne[u]=v

class dfs:
    def __init__(self, n, ne):
        self.n=n
        self.ne=ne
        self.d=[0]*(n+1)
        self.f=[0]*(n+1)
        self.t=0
    def search(self, a):
        self.t+=1
        self.d[a]=self.t
        for p in ne[a]:
            if self.d[p]==0:
                self.search(p)
        self.t+=1
        self.f[a]=self.t
DFS=dfs(n,ne)
for i in range(1,n+1):
    if DFS.d[i]==0:
        DFS.search(i)
    print(i,DFS.d[i],DFS.f[i])

Python: #coding: utf-8

n = int(input())
color = ["white" for i in range(n)]
d = [[] for i in range(n)]
global t
t = 0
M = [[False for i in range(n)] for j in range(n)]
for i in range(n):
    data = list(map(int,input().split()))
    u = data[0]
    k = data[1]
    if i == 0:
        start = u
    for v in data[2:2+k]:
        M[u-1][v-1] = True


def search(u,t):
    t += 1
    color[u-1] = "gray"
    d[u-1].append(t)
    for v in range(n):
        if M[u-1][v-1] and color[v-1] == "white":
            t = search(v,t)
    color[u-1] = "black"
    t += 1
    d[u-1].append(t)
    return t

search(start, t)
for i in range(n):
    print(i+1, d[i][0], d[i][1])

Python: def depth_search(u, t):
    t += 1
    s.append(u)
    d[u] = t
    for v in range(N):
        if adjacency_list[u][v] == 0:
            continue 
        if d[v] == 0 and v not in s:
            t = depth_search(v, t)
    t += 1
    s.pop()
    f[u] = t
    return t

N = int(input())
adjacency_list = [[0 for j in range(N)] for i in range(N)]
for _ in range(N):
    u, k, *v = input().split()
    for i in v:
        adjacency_list[int(u)-1][int(i)-1] = 1

s = []
d = [0 for _ in range(N)]
f = [0 for _ in range(N)]

t = 0
for u in range(N):
    if d[0] == 0:
        t = depth_search(u, t)

for i in range(N):
    print("{} {} {}".format(i+1, d[i], f[i]))

Python: import sys
sys.setrecursionlimit(10 ** 9)

N = int(input())
graph = list()
for i in range(N):
  x = list(map(int, input().split()))
  graph.append(x[2:])

start = [0] * N
end = [0] * N
visited = [False] * N
time = 0
def dfs(n):
  if visited[n]:
    return
  visited[n] = True
  global time
  time += 1
  start[n] = time
  for i in graph[n]:
    dfs(i-1)
  time += 1
  end[n] = time

for i in range(N):
  dfs(i)
for i in range(N):
  print(i+1, start[i], end[i])