Go: package main

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

/***************************************************************
stackによる深さ優先探索を実装する。
***************************************************************/

const (
	N     = 100
	WHITE = 0
	GRAY  = 1
	BLACK = 2
)

var (
	n            int
	Adj          [N][N]int
	statusColor  [N]int
	discoverTime [N]int
	finishTime   [N]int
	clock        int
	nt           [N]int
)

/***************************************************************
Stackの定義:
- field
	container: ノードの格納されたスライス
	sp: スタックポインタ
- method
	size(): スタックに積まれているノードの個数を返す
	top(): スタックの一番上に積まれているノードを返す
	isEmpty(): スタックが空かどうかを返す
	pop(): スタックの要素をポップし削除する
	push(): スタックに要素を積む
***************************************************************/

type Stack struct {
	container []int
	sp        int
}

func (s *Stack) size() int {
	return len(s.container)
}

func (s *Stack) top() int {
	return s.container[s.sp]
}

func (s *Stack) isEmpty() bool {
	return s.sp == 0
}

func (s *Stack) pop() int {
	_pop := func() {
		s.container = s.container[:len(s.container)-1]
	}
	defer _pop()
	if s.isEmpty() {
		panic("There is no elements in stack!")
	}
	s.sp--
	return s.container[s.sp]
}

func (s *Stack) push(n int) {
	s.sp++
	s.container[s.sp] = n
}

func next(u int) int {
	for v := nt[u]; v < n; v++ {
		nt[u] = v + 1
		if Adj[u][v] == 1 {
			return v
		}
	}
	return -1
}

func _DFS(target int) {
	for i := 0; i < n; i++ {
		nt[i] = 0
	}
	stack := new(Stack)
	stack.container = make([]int, N+1)
	stack.push(target)
	statusColor[target] = GRAY
	clock++
	discoverTime[target] = clock
	for !stack.isEmpty() {
		u := stack.top()
		v := next(u)
		if v != -1 {
			if statusColor[v] == WHITE {
				statusColor[v] = GRAY
				clock++
				discoverTime[v] = clock
				stack.push(v)
			}
		} else {
			stack.pop()
			statusColor[u] = BLACK
			clock++
			finishTime[u] = clock
		}
	}
}

func DFS() {
	for i := 0; i < n; i++ {
		statusColor[i] = WHITE
		nt[i] = 0
	}
	clock = 0
	for i := 0; i < n; i++ {
		if statusColor[i] == WHITE {
			_DFS(i)
		}
	}
	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", i+1, discoverTime[i], finishTime[i])
	}
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	scanner.Scan()
	n, _ = strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		for j := 0; j < n; j++ {
			Adj[i][j] = 0
		}
	}
	for i := 0; i < n; i++ {
		scanner.Scan()
		u, _ := strconv.Atoi(scanner.Text())
		scanner.Scan()
		k, _ := strconv.Atoi(scanner.Text())
		u--
		for j := 0; j < k; j++ {
			scanner.Scan()
			v, _ := strconv.Atoi(scanner.Text())
			v--
			Adj[u][v] = 1
		}
	}

	DFS()
}

C++: #include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<bitset>
#include<vector>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<iomanip>
#include <functional>
using namespace std;
typedef long long ll;
const int mod = 1000000007;
const int INF = 1 << 28;
//cout << fixed << std::setprecision(9)
//memset(a, 0, sizeof(a));
//--------------------------

int n;
bool g[110][110];
int d[110];
int f[110];

void dfs1(int s)
{
	if (d[s] != -1) return;

	stack<int> stk;
	d[s] = 0;
	stk.push(s);
	int current = 0;
	while (!stk.empty()) {
		int u = stk.top();
		int flag = 0;
		for (int j = 1; j <= n; j++) {
			if (g[u][j] && d[j] == -1) {
				flag = 1;
				stk.push(j);
				d[j] = ++current;
				break;
			}
		}

		if (flag == 0) {
			f[u] = ++current;
			stk.pop();
		}

	}
}

void dfs()
{
	for (int i = 1; i <= n; i++)
		dfs1(i);

}

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

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

	dfs();

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

	return 0;
}

C++: #define _USE_MATH_DEFINES

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <list>

long long int INF = 1e18;
using namespace std;

typedef pair<long long int, long long int> P;

long long int DP[1001][1001] = {};

int n;
int s[200], t[200];
bool visited[200] = {};

int dfs(int u, int d){
	if(visited[u]){
		return d - 1;
	}
	visited[u] = true;
	s[u] = d;
	for(int i = 0; i < n; i++){
		if(DP[u][i]){
			d = dfs(i, d + 1);
		}
	}
	t[u] = d + 1;
	return d + 1;
}

int main(){
	
	cin >> n;
	
	for(int loop = 0; loop < n; loop++){
		
		int id, k;
		cin >> id >> k;
		id--;
		
		for(int i = 0; i < k; i++){
			int num;
			cin >> num;
			num--;
			DP[id][num] = 1;
		}
		
	}
	
	dfs(0, 1);
	
	for(int i = 0; i < n; i++){
		cout << i + 1 << " " << s[i] << " " << t[i] << endl;
	}
	
	return 0;
}

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

using namespace std;

const int MAX = 100;

class DFS
{
    vector< vector<int> > adj;
    int num, d[MAX], f[MAX], parent[MAX], status[MAX], tt;

public:
    DFS()
    {
        cin >> num;
        for (int i = 0; i < num; i++)
        {
            d[i] = status[i] = 0;
            parent[i] = -1;
        }

        load(num);
        tt = 0;
    }

    void load(int n)
    {
        int r, c, n_c;
        adj.assign(n, vector<int>());
        for (int i = 0; i < n; i++)
        {
            cin >> r >> n_c;
            adj[r - 1].assign(n_c, int());
            for (int j = n_c - 1; j >= 0; j--)
            {
                cin >> c;
                adj[r - 1].at(j) = c-1;
            }
        }
    }

    int next(int node)
    {
        if (!adj[node].empty())
        {
            int v = adj[node].back();
            adj[node].pop_back();
            return v;
        }
        return -1;
    }

    void run(int node)
    {
        int next_node;
        while (node != -1)
        {
            if (status[node] == 0)
            {
                status[node] = 1;
                d[node] = ++tt;
            }
            next_node = next(node);
            if (next_node == -1)
            {
                status[node] = 2;
                f[node] = ++tt;
                node = parent[node];
                continue;
            }
            if (status[next_node] == 0)
            {
                parent[next_node] = node;
                node = next_node;
            }
        }
    }

    void dfs(){
        for(int node=0;node<num;node++){
            if(status[node] == 0) run(node);
        }
    }

    int dd(int n)
    {
        return d[n];
    }

    int ff(int n)
    {
        return f[n];
    }

    int number()
    {
        return num;
    }
};

int main()
{
    DFS dfs;

    dfs.dfs();
    for (int i = 0; i < dfs.number(); i++)
    {
        cout << i + 1 << " " << dfs.dd(i) << " " << dfs.ff(i) << endl;
    }
}