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 <iomanip> // << fixed << setprecision(xxx)
#include <algorithm> // do { } while ( next_permutation(A, A+xxx) ) ;
#include <vector>
#include <string> // to_string(nnn) // substr(m, n) // stoi(nnn)
#include <complex>
#include <tuple> // get<n>(xxx)
#include <queue>
#include <stack>
#include <map> // if (M.find(key) != M.end()) { }
#include <set> // S.insert(M);
// if (S.find(key) != S.end()) { }
// for (auto it=S.begin(); it != S.end(); it++) { }
// auto it = S.lower_bound(M);
#include <random> // random_device rd; mt19937 mt(rd());
#include <cctype>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib> // atoi(xxx)
using namespace std;

#define DEBUG 0 // change 0 -> 1 if we need debug.
// insert #if<tab> by my emacs. #if DEBUG == 1 ... #end

typedef long long ll;

// const int dx[4] = {1, 0, -1, 0};
// const int dy[4] = {0, 1, 0, -1};

// const int C = 1e6+10;
// const ll M = 1000000007;

class Edge {
public:
  int src, dst, cost;
  Edge(int s, int d, int c)
    : src(s), dst(d), cost(c) {}
  friend bool operator<(const Edge& x, const Edge& y) {
    return x.cost < y.cost;
  }
};

typedef Edge State;

class Graph {
public:
  int N;
  vector<Edge>* V;
  int* visited;
  int* from;
  int time;
  int* time_d;
  int* time_f;

  Graph(int n)
    : N(n), time(0) {
    V = new vector<Edge>[N];
    from = new int[N];
    time_d = new int[N];
    time_f = new int[N];
    visited = new int[N];
    fill(visited, visited+N, 0);
  }
  ~Graph() {
    delete[] V;
    delete[] from;
    delete[] time_d;
    delete[] time_f;
    delete[] visited;
  }

  void add_edge(int src, int dst, int cost = 1) {
    V[src].push_back(Edge(src, dst, cost));
  }

  void dfs(int start) {
    stack<State> S;
    S.push(State(-1, start, 0));
    while (!S.empty()) {
      State s = S.top();
      S.pop();
      if (visited[s.dst] == 0) {
        visited[s.dst] = 1;
        time_d[s.dst] = time++;
        from[s.dst] = s.src;
        S.push(s);
        for (auto x : V[s.dst]) {
          if (visited[x.dst] == 0) {
            S.push(State(s.dst, x.dst, s.cost + x.cost));
          }
        }
      } else if (visited[s.dst] == 1) {
        visited[s.dst] = 2;
        time_f[s.dst] = time++;
      }
    }
  }
};

int main () {
  int n;
  cin >> n;
  Graph graph(n);
  for (auto i = 0; i < graph.N; ++i) {
    int u, k;
    cin >> u >> k;
    --u;
    for (auto j = 0; j < k; ++j) {
      int v;
      cin >> v;
      --v;
      graph.add_edge(u, v);
    }
  }
  for (auto i = 0; i < graph.N; ++i) {
    sort(graph.V[i].begin(), graph.V[i].end());
    reverse(graph.V[i].begin(), graph.V[i].end());
  }
  while (true) {
    bool used = false;
    for (auto i = 0; i < graph.N; ++i) {
      if (graph.visited[i] == 0) {
        graph.dfs(i);
        used = true;
        break;
      }
    }
    if (!used) break;
  }
  for (auto i = 0; i < graph.N; ++i) {
    cout << i+1
         << " " << graph.time_d[i]+1
         << " " << graph.time_f[i]+1 << endl;
  }
}

C++: #include <iostream>
#include <vector>
using namespace std;

int t = 0;
vector<int> edge[101];
bool back_edge[101];

pair<int, int> visit_time[101];

void dfs(int cur)
{
    t += 1;
    visit_time[cur].first = t;

    for (int i = 0; i < (int)edge[cur].size(); i++) // cur から行ける頂点について
    {
        if (back_edge[edge[cur][i]] == false)
        {
            back_edge[edge[cur][i]] = true;
            dfs(edge[cur][i]);
        }
    }

    t += 1;
    visit_time[cur].second = t;
}

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

    for (int i = 0; i < n; i++)
    {
        int u, k;
        cin >> u >> k;
        back_edge[u] = false;
        for (int j = 0; j < k; j++)
        {
            int v;
            cin >> v;
            edge[u].push_back(v);
        }
    }

    for (int i = 1; i < n; i++)
        if (back_edge[i] == false)
        {
            back_edge[i] = true;
            dfs(i);
        }

    for (int i = 1; i <= n; i++)
    {
        cout << i
             << " " << visit_time[i].first
             << " " << visit_time[i].second << endl;
    }
}

C++: #include<stdio.h>
#include<iostream>
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

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

void dfs_visit(int u){
    int v;
    color[u]=GRAY;
    d[u]=++tt; //最初の訪問
    for(v=0; v<n; v++){
        if(M[u][v]==0){ continue; }
        if(color[v]==WHITE){ dfs_visit(v); } 
    }
    color[u]=BLACK;
    f[u]=++tt;//訪問の完了
}

void dfs(){
    int u;
    //初期化
    for(u=0; u<n; u++){ 
        color[u]=WHITE; 
    }

    tt=0;

    for(u=0; u<n; u++){
        //未訪問のuを始点として深さ優先探索
        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,v,k,i,j;

    scanf("%d",&n);
    for(i=0; i<n; i++){
        for(j=0; j<n; j++){
            M[i][j]=0;
        }
    }

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

    dfs();

    return 0;
}