Go: package main

import "fmt"

type node struct {
	id, d, v int
	adj      []node
}

var n int
var seen []bool
var graph []node

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func dfs(v, t int) int {
	// fmt.Printf("dfs(v %d, t %d) en:\n", v, t)
	seen[v] = true
	graph[v].v = t
	tt := t
	for _, vv := range graph[v].adj {
		if !seen[vv.id] {
			tt = max(tt, dfs(vv.id, tt+1))
		}
	}
	graph[v].d = tt + 1
	// fmt.Printf("dfs(v %d, t %d) ex: d %d\n", v, t, graph[v].d)
	return graph[v].d
}

func main() {
	fmt.Scan(&n)
	graph = make([]node, n+1)
	for i := 1; i <= n; i++ {
		var u, k, v int
		fmt.Scan(&u, &k)
		graph[u].id = u
		// 頂点uはk個の隣接頂点を持っている
		for j := 0; j < k; j++ {
			fmt.Scan(&v)
			var t node
			t.id = v
			graph[u].adj = append(graph[u].adj, t)
		}
	}
	// fmt.Println("n", n, "graph", graph)
	seen = make([]bool, n+1)
	// t := dfs(1, 1)
	v, t := 1, 1
	done := false
	for !done {
		tt := dfs(v, t)
		done = true
		for i := range seen {
			if !seen[i] {
				done = false
				v = graph[i].id
				t = tt
				break
			}
		}
	}
	for i := 1; i <= n; i++ {
		fmt.Printf("%d %d %d\n", i, graph[i].v, graph[i].d)
	}
}

C++: #include <cstdio>
#include <cstdlib>
#include <string>
#include <iostream>
#include <stack>

using namespace std;
static const int N=100;
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;

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

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

void dfs(){
    int u;
    tt=0;
    for (u=0;u<n;u++)color[u]=WHITE;

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

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

C++: #include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
typedef vector<ll> Vec;
typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<P> VP;
typedef vector<vector<ll>> VV;
typedef vector<vector<int>> VVi;

#define REP(i, a, b) for(ll i=(a); i<(b); i++)
#define PER(i, a, b) for(ll i=(a); i>=(b); i--)
#define rep(i, n) REP(i, 0, n)
#define per(i, n) PER(i, n, 0)
const ll INF=1e18+18;
const ll MAX=100005;
const ll MOD=1000000007;
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl;
#define YES(n) cout << ((n) ? "YES" : "NO") << endl;
#define ALL(v) v.begin(), v.end()
#define rALL(v) v.rbegin(), v.rend()
#define pb(x) push_back(x)
#define mp(a, b) make_pair(a,b)
#define Each(a,b) for(auto &a :b)
#define REPM(i, mp) for (auto i = mp.begin(); i != mp.end(); ++i)
#define dbg(x_) cerr << #x_ << ":" << x_ << endl;
#define dbgmap(mp) cerr << #mp << ":"<<endl; for (auto i = mp.begin(); i != mp.end(); ++i) { cerr << i->first <<":"<<i->second << endl;}
#define dbgarr(n,m,arr) rep(i,n){rep(j,m){cerr<<arr[i][j]<<" ";}cerr<<endl;}
#define dbgdp(n,arr) rep(i,n){cerr<<arr[i]<<" ";}cerr<<endl;
#define dbgmint(n,arr) rep(i,n){cerr<<arr[i].x<<" ";}cerr<<endl;
#define out(a) cout<<a<<endl
#define out2(a,b) cout<<a<<" "<<b<<endl
#define vout(v) rep(i,v.size()){cout<<v[i]<<" ";}cout<<endl
#define Uniq(v) v.erase(unique(v.begin(), v.end()), v.end())
#define fi first
#define se second

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

template<typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &p) { return s<<"("<<p.first<<", "<<p.second<<")"; }

template<typename T>istream& operator>>(istream&i,vector<T>&v)
{rep(j,v.size())i>>v[j];return i;}

// vector
template<typename T>
ostream &operator<<(ostream &s, const vector<T> &v) {
    int len=v.size();
    for(int i=0; i<len; ++i) {
        s<<v[i];
        if(i<len-1) s<<"	";
    }
    return s;
}

// 2 dimentional vector
template<typename T>
ostream &operator<<(ostream &s, const vector<vector<T> > &vv) {
    int len=vv.size();
    for(int i=0; i<len; ++i) {
        s<<vv[i]<<endl;
    }
    return s;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout<<std::setprecision(10);

    ll n;
    cin>>n;
    VV g(n);
    rep(i,n){
        ll u,k;
        cin>>u>>k;
        u--;
        rep(j,k){
            ll x;
            cin>>x;
            x--;
            g[u].pb(x);
        }
    }

    Vec d(n,-1);
    Vec f(n,-1);
    ll time = 0;
    auto dfs = [&](auto dfs,ll v)->void{
        Each(x,g[v]){
            if(d[x]==-1){
                time++;
                d[x] = time;
                dfs(dfs,x);
            }
        }
        if(f[v]==-1){
            time++;
            f[v] = time;
        }
    };
    rep(i,n){
        if(d[i]==-1){
            time++;
            d[i] = time;
        }
        dfs(dfs,i);
    }
    rep(i,n){
        cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;
    }
    return  0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define int long long
vector<vector<int> > G;
int d[111],f[111],u[111];
void dfs(int v,int& p){
  if(u[v]) return;
  u[v]=1;
  sort(G[v].begin(),G[v].end());
  d[v]=++p;
  for(int u:G[v]) dfs(u,p);
  f[v]=++p;
}
signed main(){
  int n;
  cin>>n;
  G.resize(n,vector<int>());
  for(int i=0;i<n;i++){
    int u,k;
    cin>>u>>k;
    u--;
    for(int j=0;j<k;j++){
      int c;
      cin>>c;
      c--;
      G[u].push_back(c);
    }
  }
  int p=0;
  dfs(0,p);
  for(int i=0;i<n;i++) cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;;
  return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;

#define ul unsigned long long
#define ll long long

ll g[101][101],a[101][2],ct;

void dfs(ll ci) {
  //cout<<ci<<endl;
  if (a[ci][0]) return;
  ll ni;
  ct++;
  a[ci][0]=ct;

  for (ll i = 1; i <= g[ci][0]; i++)
  {
    ni=g[ci][i];
    if (ni>0) {
      g[ci][i] = 0;
        dfs(ni);
    }
  }

  ct++;
  a[ci][1] = ct;
}

int main()
{
  ll n,ci;
  cin>>n;
  fill_n(a[0],101*2,0);
  a[0][0]=1;
  ct=0;

  for (ll i = 0; i < n; i++)
  {
    cin>>ci;
    cin>>g[ci][0];
    for (ll j = 1; j <= g[ci][0]; j++)
    {
      cin>>g[ci][j];
    }
  }

  for (ll i = 1; i <= n; i++)
  {
    dfs(i);
  }
  

  for (ll i = 1; i <= n; i++)
  {
    cout<< (i) <<" "<<a[i][0]<<" "<<a[i][1]<<endl;
  }
  

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG

vector<int> d;
vector<int> f;
int t;

void dfs(int p, vector<vector<int>> dst) {
  d[p] = t;
  for (int x : dst[p]) {
    if (!d[x]) {
      ++t;
      dfs(x, dst);
    }
  }
  f[p] = ++t;
}

int main() {
  int n;
  cin >> n;
  // bug
  vector<vector<int>> dst;
  dst = vector<vector<int>>(n + 1);
  d = vector<int>(n + 1, 0);
  f = vector<int>(n + 1, 0);
  for (int i = 1; i <= n; i++) {
    int u, k;
    cin >> u >> k;
    for (int j = 0; j < k; j++) {
      int v;
      cin >> v;
      dst[u].push_back(v);
    }
  }
  t = 0;
  // bug:未発見の頂点が残る場合を考えていなかった。
  // dfs(1, 1);
  for (int i = 1; i <= n; i++) {
    if (!d[i]) {
      ++t;
      dfs(i, dst);
    }
  }
  for (int i = 1; i <= n; i++) {
    cout << i << ' ' << d[i] << ' ' << f[i] << endl;
  }
}