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>
using namespace std;
#define MAX 101
#define NIL -1
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n, t, top, u[MAX], color[MAX], M[MAX][MAX], S[MAX], d[MAX], f[MAX];

int next(int u){
  for(int i=1; i<=n; i++){
    if(M[u][i] == 1 && color[i] == WHITE){
      return i;
    }
  }
  return NIL;
}

void dfs(int u){
  int v;
  S[++top] = u;
  color[u] = GRAY;
  d[u] = ++t;

  while(top > 0){
    u = S[top];
    v = next(u);
    if(v != NIL){
      color[v] = GRAY;
      d[v] = ++t;
      S[++top] = v;
    }else{
      top--;
      color[u] = BLACK;
      f[u] = ++t;
    }
  }
}

void dfs_init(){
  for(int i=0; i<MAX; i++){
    color[u[i]] = WHITE;
  }

  t = 0;
  top = 0;
}

int main(void){
  int k, m;
  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[i] >> k;
    for(int j=0; j<k; j++){
      cin >> m;
      M[u[i]][m] = 1;
    }
  }

  dfs_init();
  for(int i=0; i<n; i++){
    if(d[u[i]] == 0) dfs(u[i]);
  }

  for(int i=0; i<n; i++){
    cout << u[i] << " " << d[u[i]] << " " << f[u[i]] << endl; 
  }
  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int n,step=0,fdepth[105],sdepth[105];
bool visit[105],c[105][105];
void dfs(int node){
    step++;
    fdepth[node]=step;
    for(int i=1;i<=n;i++)
        if(!visit[i]&&c[node][i]){
            visit[i]=1;
            dfs(i);
        }
    step++;
    sdepth[node]=step;
}
int main(){
    ios_base::sync_with_stdio(0);
    //cin.tie(0);
    while(cin>>n){
        memset(fdepth,0,sizeof(fdepth));
        memset(sdepth,0,sizeof(sdepth));
        memset(c,0,sizeof(c));
        memset(visit,0,sizeof(visit));
        int parent,num,son;
        step=0;
        for(int i=0;i<n;i++){
            cin>>parent>>num;
            while(num--){
                cin>>son;
                c[parent][son]=1;
            }
        }
        visit[1]=1;
        dfs(1);
        for(int i=1;i<=n;i++)
            cout<<i<<' '<<fdepth[i]<<' '<<sdepth[i]<<'\n';
    }
    return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int) (n); i++)
using namespace std;

#define MAX 100

int d[MAX], f[MAX], t = 0, M[MAX][MAX] = {}, n;

void dfs(){
    int seen[MAX] = {};
    rep(i, n){
        if(seen[i]) continue;
        stack<int> todo;
        seen[i] = 1;
        todo.push(i);
        t++;
        d[i] = t;
        while(!todo.empty()){
            int m = todo.top();
            rep(j, n + 1){
                if(j == n){
                    todo.pop();
                    t++;
                    f[m] = t;
                    break;
                }
                if(M[m][j] && !seen[j]){
                    todo.push(j);
                    t++;
                    d[j] = t;
                    seen[j] = 1;
                    break;
                }
            }
        }
    }
}

int main(){
    cin >> n;
    rep(i, n){
        int l, p;
        cin >> l >> p;
        rep(j, p){
            int q;
            cin >> q;
            M[l - 1][q - 1] = 1;
        }
    }
    dfs();
    
    rep(i, n){
        cout << i + 1 << " " << d[i] << " " << f[i] << endl;
    }
    
    return 0;
}