Go: package main

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

func main() {
	scn := bufio.NewScanner(os.Stdin)
	scn.Split(bufio.ScanWords)
	nextInt := func() int { scn.Scan(); r, _ := strconv.Atoi(scn.Text()); return r }
	w := bufio.NewWriter(os.Stdout)

	n := nextInt()
	vecs := make([][]int, n)
	for i := 0; i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			vecs[u-1] = append(vecs[u-1], nextInt()-1)
		}
	}

	ds := make([]int, n)
	fs := make([]int, n)
	founds := make([]bool, n)
	t := 0
	for i := range founds {
		if !founds[i] {
			t = dfs(vecs, ds, fs, founds, i, t)
		}
	}

	for i := 0; i < n; i++ {
		fmt.Fprintln(w, i+1, ds[i], fs[i])
	}

	w.Flush()
}

func dfs(vecs [][]int, ds, fs []int, founds []bool, i, t int) (time int) {
	t++
	ds[i] = t
	founds[i] = true
	for _, v := range vecs[i] {
		if !founds[v] {
			t = dfs(vecs, ds, fs, founds, v, t)
		}
	}
	t++
	fs[i] = t

	return t
}

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

std::vector<std::vector<int>> edges;
std::vector<int> d, f;

// dfs(x, t) := 頂点 x に時刻 t で初めて訪れたときに d, f を更新して戻ってきたときのタイムスタンプを返す
int dfs(int x, int t) {
	d[x] = t;

	for (int i = 0; i < edges[x].size(); ++i) {
		int dist = edges[x][i];
		if (d[dist] == -1)
			t = dfs(dist, t + 1);
	}

	f[x] = t + 1;
	return f[x];
}

int main() {
	int n;
	std::cin >> n;

	edges.resize(n);
	d.resize(n, -1);
	f.resize(n);

	for (int i = 0; i < n; ++i) {
		int u, k;
		std::cin >> u >> k;
		--u;

		for (int j = 0; j < k; ++j) {
			int v;
			std::cin >> v;
			--v;

			edges[u].push_back(v);
		}
	}

	int t = 0;
	for (int i = 0; i < n; ++i)
		if (d[i] == -1)
			t = dfs(i, t + 1);

	for (int i = 0; i < n; ++i)
		std::cout << i + 1 << " " << d[i] << " " << f[i] << std::endl;
}

C++: #include <bits/stdc++.h>
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define REP(i, n) for(int i = 0; i < (n); ++i)
#define SORT(v) sort(v.begin(), v.end());
#define pb(a) push_back(a)
using ll = long long;
using namespace std;

#define WHITE 1
#define GRAY 2
#define BLACK 3

int now, n, u, k, v, tree[102][102], timeTable[102][2], color[102], timeNow = 1;
stack<int> st;

void dfs(){
    while(1){
        if(st.empty()){
            FOR(l, 1, n + 1){
                cout << l << " " << timeTable[l][0] << " " << timeTable[l][1] << endl;
            }
            break;
        }else{
            now = st.top();
          	cout << now << " " << timeNow << endl;
          	if(color[now] == WHITE){
            	timeTable[now][0] = timeNow;
            }
            color[now] = GRAY;
            int cnt = 1;
            while(1){
                if(cnt == n + 1){
                    st.pop();
                    color[now] = BLACK;
                    timeTable[now][1] = timeNow + 1;
                    break;
                }else if(tree[now][cnt] && color[cnt] == WHITE){
                    st.push(cnt);
                    break;
                }
                cnt++;
            }
            timeNow++;
        }
    }
}

int main(){
    cin >> n;
  	REP(i, 102){
    	REP(j, 102){
        	tree[i][j] = 0;
        }
    }
    REP(i, n){
        cin >> u >> k;
        color[i + 1] = WHITE;
        REP(j, k){
            cin >> v;
            tree[u][v] = 1;
        }
    }
    st.push(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;
    }
}