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 <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i < (n); i++)
#define all(a) begin(a),end(a)
template<class T> istream& operator >> (istream& s, vector<T>& v)
{ for (T& x: v) { s >> x; } return s;}
template<class T> void cout_h(const vector<T>& c, int n=INT_MAX)
{ rep(i, min(n, (int)c.size())) cout << c[i] << (i==c.size()-1?"\n":" "); }
template<class T> inline bool chmin(T& a, T b) {return a>b?a=b,true:false;}
template<class T> inline bool chmax(T& a, T b) {return a<b?a=b,true:false;}
#define D1(a) cout<<#a<<":"<<a<<"\n"
#define D2(a,b) cout<<#a<<":"<<a<<","<<#b<<":"<<b<<endl 
#define D3(a,b,c) cout<<#a<<":"<<a<<","<<#b<<":"<<b<<","<<#c<<":"<<c <<endl
#define D4(a,b,c,d) cout<<#a<<":"<<a<<","<<#b<<":"<<b<<","<<#c<<":"<<c<<","<<#d<<":"<<d<<endl 
#define MOD 1000000007

typedef vvi graph;

void dfs(graph& g, vpii& ans, int& t, int v = 0)
{
    if (ans[v].first != 0) return;
    
    ans[v].first = ++t;
    
    for (int i = 0; i < g[v].size(); i++) {
        dfs(g, ans, t, g[v][i]);
    }
    
    ans[v].second = ++t;
}

int main()
{
    int n; cin >> n;
    graph g(n);
    rep(i, n) {
        int u, k; cin >> u >> k; u--;
        rep(j, k) {
            int v; cin >> v; v--;
            g[u].push_back(v);
        }
    }
    
    vpii ans(n, make_pair(0, 0));
    int t = 0;
    rep(v, n) dfs(g, ans, t, v);

    rep(i, n) {
        cout << i+1 << " " << ans[i].first << " " << ans[i].second << endl;
    }
}

C++: #include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <climits>
#include <map>
#include <list>
#include <stack>
#include <queue>
#include <vector>
#include <string>
#include <sstream>
#include <fstream>
#include <iostream>
#include <algorithm>
using namespace std;

bool rel[128][128];
int disc[128];
int comp[128];
int n, turn = 0;

void dfs(int visit, vector<int> &log){
	if(find(log.begin(), log.end(), visit) == log.end()){
		log.push_back(visit);
		disc[visit] = ++turn;
		for(int i = 1; i <= n; i++){
			if(rel[visit][i] && find(log.begin(), log.end(), i) == log.end()) dfs(i, log);
		}
		comp[visit] = ++turn;
	}
}

int main() {
	scanf("%d", &n);
	
	for(int i = 1; i <= n; i++){
		int u, k;
		scanf("%d %d", &u, &k);
		
		for(int j = 1; j <= n; j++){
			rel[u][j] = false;
		}
		while(k--){
			int v;
			scanf("%d", &v);
			rel[u][v] = true;
		}
	}
	
	vector<int> visited;
	for(int i = 1; i <= n; i++){
		dfs(i, visited);
	}
	
	for(int i = 1; i <= n; i++){
		printf("%d %d %d\n", i, disc[i], comp[i]);
	}
	return 0;
}

C++: #include<iostream>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
using namespace std;
int G[100][100] = {};
int time = 0;
typedef struct ANS
{
	int id, t, e;
	bool done;
};

void rec(ANS a[],int t)
{
	::time++;
	a[t].t = ::time;
	a[t].done = true;
	FOR(i, 0, 100)
	{
		if (G[t][i] == 1 && a[i].done == false)
		{
			rec(a, i);
		}
	}
	::time++;
	a[t].e = ::time;
}

int main()
{
	ANS ans[101];
	int n;
	cin >> n;
	FOR(i, 0, n)
	{
		ans[i].id = i + 1;
		ans[i].done = false;
		int u, m;
		cin >> u >> m;
		FOR(j, 0, m)
		{
			int l;
			cin >> l;
			G[u - 1][l - 1] = 1;
		}
	}
	rec(ans, 0);
	FOR(i, 0, n)
	{
		cout << ans[i].id << " " << ans[i].t << " " << ans[i].e << endl;
	}
	return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
// #define int long long

template <class T>
bool INRANGE(T x, T a, T b) { return a <= x && x <= b; }
template <class T>
inline bool chmin(T &a, T b)
{
    if (a > b)
    {
        a = b;
        return true;
    }
    return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}

#define REP(i, n) for (int i = 0; i < (n); ++i)
#define RREP(i, n) for (int i = (n); i >= 0; --i)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define RFOR(i, a, b) for (int i = (a); i >= (b); --i)
#define ALL(v) (v).begin(), (v).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" \
                      << " " << __FILE__ << endl;

typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<vi> vvi;
typedef pair<int, int> pii;

int t = 1;
vvi to;
vi d, f;
vector<bool> visited;

void dfs(int i) {
    i--;
    if (visited[i]) return;
    visited[i] = true;

    d[i] = t;
    t++;
    sort(ALL(to[i]));

    for (int nv : to[i]) {
        //debug(nv)
        
        dfs(nv);
    }
    
    f[i] = t;
    t++;
}
 
int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    int N;
    cin >> N;
    to = vvi(N, vi());
    REP(i, N) {
        int k, idx;
        cin >> idx >> k;
        idx--;
        to[i].resize(k);
        REP(j, k) cin >> to[idx][j];
    }
    // debug(N)

    d.resize(N);
    f.resize(N);
    visited = vector<bool>(N, false);

    
    REP(i, N){
        if (f[i] == 0) dfs(i+1);
    } 

    REP(i, N) {
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }

    return 0;
}

C++: /*
 * b.cc: 
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>

using namespace std;

/* constant */

const int MAX_N = 100;

/* typedef */

typedef vector<int> vi;

/* global variables */

vi nbrs[MAX_N];
int ds[MAX_N], fs[MAX_N];

/* subroutines */

int dfs(int u, int t) {
  ds[u] = ++t;

  for (int i = 0; i < nbrs[u].size(); i++) {
    int &v = nbrs[u][i];
    if (! ds[v]) t = dfs(v, t);
  }

  return (fs[u] = ++t);
}

/* main */

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

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

    for (int j = 0; j < k; j++) {
      int v;
      cin >> v;
      v--;
      nbrs[u].push_back(v);
    }
  }

  int t = 0;
  for (int i = 0; i < n; i++)
    if (! ds[i]) t = dfs(i, t);

  for (int i = 0; i < n; i++)
    printf("%d %d %d\n", i + 1, ds[i], fs[i]);

  return 0;
}