Go: package main

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

// repr state of visited node
// WHITE yet visit
// GEAY  visiting
// BLACK visited
const (
	WHITE int = iota
	GRAY
	BLACK
)

type dfsGraph struct {
	g      [][]int
	colors []int
	stime  []int // Start time of visiting node
	ftime  []int // Finish time of visiting node
}

var time int

func makeAdjList() [][]int {
	var n int
	fmt.Scanf("%d", &n)

	adj := make([][]int, n)
	for i := 0; i < n; i++ {
		adj[i] = make([]int, n)
	}

	sc := bufio.NewScanner(os.Stdin)
	for i := 0; i < n; i++ {
		sc.Scan()
		nodeInfo := strings.Split(sc.Text(), " ")
		outDegree, _ := strconv.Atoi(nodeInfo[1])

		if outDegree > 0 {
			for k := 0; k < outDegree; k++ {
				j, _ := strconv.Atoi(nodeInfo[k+2])
				j-- // convert 1 based to 0 based
				adj[i][j] = 1
			}
		}
	}

	return adj
}

func (dg dfsGraph) dfsVisit(u int) {
	// 頂点uを訪問中に設定
	dg.colors[u] = GRAY
	time++
	dg.stime[u] = time

	// uの隣接nodeを訪問
	for v := 0; v < len(dg.g); v++ {
		if dg.g[u][v] == 0 {
			continue // 辺がなければスキップ
		}

		// vが未訪問なら訪問
		if dg.colors[v] == WHITE {
			dg.dfsVisit(v)
		}
	}

	// 頂点uを訪問済みに設定
	dg.colors[u] = BLACK
	time++
	dg.ftime[u] = time
}

func (dg dfsGraph) dfs() {
	for i := 0; i < len(dg.g); i++ {
		if dg.colors[i] == WHITE {
			dg.dfsVisit(i)
		}
	}
}

func (dg dfsGraph) printDfsTime() {
	for i := 0; i < len(dg.g); i++ {
		fmt.Printf("%d %d %d\n", i+1, dg.stime[i], dg.ftime[i])
	}
}

func main() {
	adj := makeAdjList()
	colors := make([]int, len(adj))
	stime := make([]int, len(adj))
	ftime := make([]int, len(adj))
	graph := dfsGraph{adj, colors, stime, ftime}
	graph.dfs()
	graph.printDfsTime()
}

C++: #include <iostream>
#include <string>
#include <stack>
#include <queue>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <algorithm>

#include <cstdio>

using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define repc(i, s, n) for (int i = (s); i <= (n); i++)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; i--)
#define rrepc(i, s, n) for (int i = (s); i >= (n); i--)
#define print_array(ary, size) cout << ary[0]; rep1(i, 1, size - 1) cout << ' ' << ary[i]; cout << endl;
typedef long long ll;
typedef unsigned long long ull;

#define NODE_NUM (100)

int n;
int current_time = 0;
int M[NODE_NUM][NODE_NUM] = { 0 };
int ans[NODE_NUM][2] = { 0 };
stack<int> S;

void DepthFirstSearch(int node)
{
	int current, next;

	current_time++;

	S.push(node);
	ans[node - 1][0] = current_time;

	while (!S.empty()) {
		current_time++;

		current = S.top();
		next = -1;

		rep(i, n) {
			if (M[current - 1][i] == 1 && ans[i][0] == 0) {
				next = i + 1;
				break;
			}
		}

		if (next == -1) {
			ans[current - 1][1] = current_time;
			S.pop();
		}
		else {
			ans[next - 1][0] = current_time;
			S.push(next);
		}
	}
}

int main()
{
	int u, k, v;
	bool NowSearching = true;

	cin >> n;
	rep(i, n) {
		cin >> u >> k;
		rep(j, k) {
			cin >> v;
			M[u - 1][v - 1] = 1;
		}
	}

	rep(i, n) {
		if (ans[i][0] == 0) DepthFirstSearch(i + 1);
	}

	rep(i, n) {
		cout << i + 1 << ' ' << ans[i][0] << ' ' << ans[i][1] << endl;
	}

	return 0;
}

C++: #include <iostream>
#include<bits/stdc++.h>
using namespace std;
int n,a,m,b,s[100],t[100],cnt=1;
vector<int> v[100];
void dfs(int n){
    if(s[n]==0){s[n]=cnt;cnt++;}
    for(auto x:v[n]){
        if(s[x]==0)dfs(x);
    }
    if(t[n]==0){t[n]=cnt;cnt++;}
    return ;
}
int main(void){
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>a>>m;
        for(int j=0;j<m;j++){
            cin>>b;
            if(a==b)continue;
            v[a-1].push_back(b-1);
        }
    }
    for(int i=0;i<n;i++)if(s[i]==0)dfs(i);
    for(int i=0;i<n;i++){
        cout<<i+1<<" "<<s[i]<<" "<<t[i]<<endl;
    }
}

C++: 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 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)

C++: #include <iostream>
using namespace std;

int r[101][101];
int d[101], f[101], num, visit[101], p=0;

void dfs(int n){
    if(!visit[n]){
        visit[n]++;
        d[n] = ++p;
        for(int i=1; i<num+1; i++)
            if(r[n][i]) dfs(i);
        f[n] = ++p;
    }
}

int main(void){
    int u, k, v;
    cin >> num;
    for(int i=0; i<num; i++){
        cin >> u >> k;
        for(int j=0; j<k; j++){
            cin >> v;
            r[u][v]++;
        }
    }
    for(int i=1; i<num+1; i++){
        if(!visit[i]) dfs(i);
    }
    for(int i=1; i<num+1; i++)
        cout << i << " " << d[i] << " " << f[i] << endl;
}

C++: #include <iostream>
#include <vector>

using namespace std;

int tim = 0;
vector<vector<int>> to;
vector<bool> reached;
vector<int> d;
vector<int> f;



void dfs(int point);

int main()
{
    int n;
    cin >> n;
    to.resize(n+1);
    for(int i = 1; i <= n; i++){
        int m;
        cin >> m;
        cin >> m;
        to[i].resize(m);
        for(int j = 0; j < m; j++){
            cin >> to[i][j];
        }
    }
    
    reached.resize(n+1);
    d.resize(n+1);
    f.resize(n+1);

    dfs(1);

    for(int i = 1; i <= n; i++){
        cout << i << " " << d[i] << " " << f[i] << endl;
    }

    return 0;
}

void dfs(int point)
{
    tim++;
    reached[point] = true;
    d[point] = tim;
    for(int i = 0; i < to[point].size(); i++){
        if(!reached[to[point][i]]){
            dfs(to[point][i]);
        }
    }
    tim++;
    f[point] = tim;
}

C++: #include <iostream>
using namespace std;

const int N = 100;
const int white = 0;
const int gray = 1;
const int black = 2;

int n,M[N][N];
int color[N],d[N],f[N],tt;

//?????°dfs
void dfs_visit(int u){
    int v;
    color [u] = gray;
    d[u] = ++tt; //??????????¨????
    for ( 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(){
    int u;
    for (u = 0; u < n; ++u) {
        color[u] = white;
    }
    tt = 0;

    for (int u = 0; u < n ; ++u) {
        //????¨???????u????§??????¨????????±???????????¢?´¢
        if(color[u] == white) dfs_visit(u);
    }
    for (int u = 0; u < n ; ++u) {
        cout << u+1 << " " << d[u] << " " << f[u] << " " << endl;
    }
}

int main(){
    int u,v,k;
    M[N][N] = {0};
    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();
    return 0;

}