Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveDfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

func nextInt(sc *bufio.Scanner) (int, error) {
	return strconv.Atoi(nextText(sc))
}

C++: #include<iostream>
#include<cstdio>
using namespace std;
int arisutoteresu[200][200] = {0};
int imap[200][200] = {0};
int n,u[200],k[200];
int GetIt[200]={0};
int FinIt[200]={0};
bool used[200];
int fincou=1;
int Gcounter;
int Fcounter;
int Find;
void dfs(int where){
  fincou++;
  Fcounter++;
  //cout << "where " << where << " " << Find << endl; 
  GetIt[where]=Find;
  //cout << "GetIt[" << where << "] = " << GetIt[where] << endl;
 
  if(k[where] != 0){
    for(int i=0;i<k[where];i++){
      if(!used[imap[where][i]]){
	Gcounter++;
	Find++;

	used[imap[where][i]] = true;
	dfs(imap[where][i]);
	fincou++;
	Fcounter++;

      }
    }
  }
    FinIt[where] = fincou;
     
}
 
int main(){
  
  int ad;
   
  scanf("%d",&n);
  for(int i=0;i<n;i++){
    cin >> u[i];
    cin >> k[u[i]];
    for(int j=0;j<k[u[i]];j++){
      cin >> ad;
      imap[u[i]][j] = ad;
    }
  }
 
 
  for(int j=0;j<200;j++)used[j] = false;
  Gcounter=Fcounter=1;
 
  Find = 1;
  int Index=0;
  bool fin = true;
  fincou = 1;

  
    for(int i=0;i<n;i++){
      if(!used[u[i]]){//cout << "not used" << u[i] << endl;
	used[u[i]]=true;

      dfs(u[i]);
      Find = fincou+1;
      fincou++;      
      }
    }
  
  //dfs(u[0]);   

   
  
  //cout << "counter - " << Find << ", F" << fincou << endl;
  for(int i=0;i<n;i++){
    cout << u[i] << " " << GetIt[u[i]]  << " " << FinIt[u[i]];
    cout << endl;
  }
 
  return 0;
}

C++: #include<cstdio>
#include<queue>
#include<stack>
const int N = 101;
std::queue<int> Q[N];
void dfs(int root, int *tt, int d[], int f[]);
int main() {
    int n; scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        int k;
        scanf("%d%d", &i, &k); //&i, so i--;
        for (int j = 0; j < k; j++) {
            int v; scanf("%d", &v);
            Q[i].push(v);//remember children
            //i starts from 1!. look scanf above
        }
        i--;
    }
    int d[N] = {0}, f[N] = {0}, tt = 0;
    for (int i = 1; i <= n; i++) if(!d[i]) dfs(i, &tt, d, f);//if cannot reach from 0
    for (int i = 1; i <= n; i++) printf("%d %d %d\n", i, d[i], f[i]);
    return 0;
}
void dfs(int root, int *tt, int d[], int f[]) {//from root search
    std::stack<int> S;
    S.push(root);
    d[root] = ++*tt;
    while (!S.empty() ) {
        int u = S.top();
        if (!Q[u].empty() ) {
            int v = Q[u].front();
            Q[u].pop();
            if (d[v] == 0) {
                d[v] = ++*tt;
                S.push(v);
            }
        } else {
            S.pop();
            f[u] = ++*tt;
        }
        
    }
}

C++: #include <iostream>
#include <vector>
#include <vector>
#include <algorithm>
#include <stack>

using namespace std;

static const int N = 100;
int n, m[N][N];
int tm, begT[N], endT[N];
bool visited[N];

int nxt(int u)
{
	for (int v = 0; v < n; ++v)
	{
		if (m[u][v] > 0 && !visited[v]) return v;
	}
	return -1;
}

void dfs_helper(int idx)
{
	stack<int> s;
	s.push(idx);
	begT[idx] = tm++;
	visited[idx] = true;

	while (!s.empty())
	{
		int u = s.top();
		int v = nxt(u);
		if (-1 == v)
		{
			s.pop();
			endT[u] = tm++;
			continue;
		}
		s.push(v);
		begT[v] = tm++;
		visited[v] = true;
	}
}

void dfs()
{
	tm = 1;

	for (int i = 0; i < n; ++i)
	{
		if (!visited[i]) dfs_helper(i);
	}

	for (int i = 0; i < n; ++i)
	{
		cout << i + 1 << " " << begT[i] << " " << endT[i] << endl;
	}
}

int main()
{
	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)
		visited[i] = false;

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

	dfs();

	return 0;
}

C++: #if 0

#endif

#include <iostream>
#include <vector>
using namespace std;

int n;
int t; //mytime?????????????????§???????´?
int mytime1[110],mytime2[110]; //?????§??????
int G[110][110];
int c[110];

void dfs(int cur){
	t+=1;
	mytime1[cur]=t;
	c[cur]=1;
	for(int dst=0; dst<n; ++dst){
		if(G[cur][dst]==1&&c[dst]==0){
			cout<<1<<endl;
			dfs(dst);
		}
	} 
	t += 1;
	mytime2[cur]=t;
}


int main()
{
	int G[110][110];
	cin>>n;
	for(int i=0;i<n;i++){
		int u,k;
		cin>>u>>k;
		for(int j=0;j<k;j++){
			int tmp;
			cin>>tmp;
			G[u][tmp]=1;
		}
	}
	
	}
	for(int i=0;i<n;++i){
		dfs(i);
		cout<<(i+1)<<' '<<mytime1[i+1]<<" "<<mytime2[i+1] <<endl;
}
}

C++: #include <iostream>
#include <vector>

using namespace std;

struct Edge
{
	int to;
};

vector<vector<int>> DFS(vector<vector<Edge>>& G)
{
	int timecounter = 0;
	vector<vector<int>> result;
	result = vector<vector<int>>(2, vector<int>(G.size(), 0));
	vector<int> prev(G.size(),0);
	
	for(int i = 0; i < G.size(); i++){
		int next = i + 1;
		while(result[1][i] == 0){
			int tmp;
			if(result[0][next - 1] == 0){
				timecounter += 1;	
				result[0][next - 1] = timecounter;
			}

			if(G[next - 1].empty()){
				if(result[1][next - 1] == 0){
					timecounter += 1;
					result[1][next - 1] = timecounter;
				}
				next = prev[next - 1];
			}else{
				tmp = G[next - 1].begin()->to;
				G[next - 1].erase(G[next - 1].begin());
				prev[tmp - 1] = next;
				next = tmp;
			}
		}
	}
	return result;
}

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

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

	vector<vector<int>> timestump = DFS(AdjList);
	
	for(int i = 0; i < AdjList.size(); i++){
		cout << i + 1 << " " << timestump[0][i] << " " << timestump[1][i] << endl;
	}
	return 0;
}