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)
	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 <sstream>
int used[101]={0};
int V[101][101]={0};
int first[101]={0};
int finish[101]={0};
int t=1;
int n;

void search(int i){
  first[i]=t++;
  used[i]++;
  for(int j=0;j<n;j++){
    if(V[i][j]==1 and used[j]==0){
      search(j);
    }
  } 
  finish[i]=t++;
}



int main () {
  int k;
  int u1,u;
  std::cin>>n;
  for(int i=0;i<n;i++){
    for(int j=0;j<n;j++){
      V[i][j]=0;
    }
  }
  for(int i=0;i<n;i++){
    std::cin>>u1>>k;
    for(int j=0;j<k;j++){
      std::cin>>u;
      V[u1-1][u-1]=1;
    }
  }
  for(int i=0;i<n;i++){
    if(used[i]==0){
      search(i);
    }
  }
  for(int i=0;i<n;i++){
    std::cout<<i+1<<" "<<first[i]<<" "<<finish[i]<<"\n";
  }


  return 0;
}

C++: #include <iostream>
#include<stdio.h>
#include<stack>

#define MAX 100
#define WHITE 1
#define GRAY 2
#define BLACK 3

using namespace std;

int color[MAX], d[MAX], f[MAX];
int n, A[MAX][MAX];
int tt = 0;

void dfs_visit_1(int u) { //???????????°
    color[u] = GRAY;
    d[u] = ++tt;
    for(int v = 0; v < n; v++) {
        if(A[u][v] == 0) continue;
        if(color[v] == WHITE) dfs_visit_1(v);
    }
    color[u] = BLACK;
    f[u] = ++tt;
}

void dfs_1() { // ???????????°
    for(int i = 0; i < n; i++) {
        color[i] = WHITE;
    }
    tt = 0;
    for(int i = 0; i < n; i++) {
        if(color[i] == WHITE) dfs_visit_1(i);
    }

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

}

int next(int u) {
    for(int v = 0; v < n; v++) {
        if(A[u][v] == 1) {
            /*
            if(color[v] == WHITE) return v;
            else if(color[v] == BLACK) return -1;
            else if(color[v] == GRAY) continue;
            */
            return v;
        }
    }
    return -1;
}

void dfs_visit_2(int u) {
    color[u] = GRAY;
    d[u] = ++tt;
    stack<int> S;
    S.push(u);

    while(!S.empty()) {
        int u = S.top();
        int v = next(u);
        if(v != -1) {
            if(color[v] == WHITE) {
                color[v] = GRAY;
                d[v] = ++tt;
                S.push(v);
            }
        }else {
            S.pop();
            color[u] = BLACK;
            f[u] = ++tt;
        }
    }
}


int main()
{
    int u, k, v;
    scanf("%d",&n);

    for(int i = 0; i < n; i++) {
        scanf("%d%d", &u, &k);
        for(int j = 0; j < k; j++) {
            scanf("%d", &v);
            A[u-1][v-1] = 1;
        }
    }


    /*
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < n; j++) {
            printf("%d", A[i][j]);
            if(j != n-1) printf(" ");
        }
        printf("\n");
    }
    */

    for(int i = 0; i < n; i++) {
        color[i] = WHITE;
    }
    dfs_visit_1(0);
    for(int i = 0; i < n; i++) {
        printf("%d %d %d\n", i+1, d[i], f[i]);
    }

    return 0;
}

C++: #include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;
#define rep(i,n) for(ll i=0;i<(n);i++)
#define repr(i,n) for(ll i=(n-1);i>=0;i--)
#define all(x) x.begin(),x.end()
#define br cout << "\n";
using namespace std;
const long long INF = 1e10;
const long long MOD = 1e9+7;
using Graph = vector<vector<ll>>;
using pll = pair<ll, ll>;
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;}

// 0 false, 1 true 
// string to int : -48
// a to A : -32
// ceil(a)  1.2->2.0
// c++17	g++ -std=c++17 a.cpp

ll n;
vector<vector<ll>> to(n);
vector<bool> seen(n);
vector<ll> d(n);
vector<ll> f(n);

ll dfs(ll node, ll time){
    if(seen[node] == false){
        seen[node] = true;
        d[node] = time;
    }

    for(ll next : to[node]){
        if(seen[next]){
            continue;
        }else{
            time = dfs(next, time+1);
        }
    }
    time += 1;

    f[node] = time;

    return time;
}

int main() {
    std::cout << std::fixed << std::setprecision(15);
    cin >> n;
    to.resize(n);
    seen.resize(n);
    d.resize(n);
    f.resize(n);
    rep(i, n){
        ll u; cin >> u; u--;
        ll k; cin >> k;
        rep(j, k){
            ll v; cin >> v; v--;
            to[u].push_back(v);
        }
    }

    ll time = 0;
    for(ll i = 0; i < n; i++){
        if(seen[i] == false){
            time = dfs(i, time+1);
        }
    }
    

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






}