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 <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 color[N], d[N], f[N], tt;
int nt[N];

int next(int u) {
    for (int v = nt[u]; v < n; ++v) {
        nt[u] = v + 1;
        if (M[u][v])
            return v;
    }
    return -1;
}

void dfs_visit(int r) {
    for (int i = 0; i < n; ++i) {
        nt[i] = 0;
    }

    stack<int> S;
    S.push(r);
    color[r] = GRAY;
    d[r] = ++tt;

    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;
        }
    }
}

void dfs() {
    // ?????????
    for (int i = 0; i < n; ++i) {
        color[i] = WHITE;
        nt[i] = 0;
    }
    tt = 0;

    // ????¨??????? u ????§??????¨????????±???????????¢?´¢
    for (int u = 0; u < n; ++u) {
        if (color[u] == WHITE)
            dfs_visit(u);
    }

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

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;
        }
    }

    dfs();

    return 0;
}

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

int main(){
 
  int ad;
  
  scanf("%d",&n);
  for(int i=0;i<n;i++){
    cin >> u;
    cin >> k[u];
    for(int j=0;j<k[u];j++){
      cin >> ad;
      arisutoteresu[u][ad] = 1;
      imap[u][j] = ad; 
    }
  }


  for(int j=0;j<n;j++)used[j] = false;
  dfs(1,1);

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

  return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <cstdio>
#include <vector>
#include <stack>
using namespace std;
#define maxn 105
const int WHITE = 0;
const int GRAY  = 1;
const int BLACK = 2;
int g[maxn][maxn];
int d[maxn],f[maxn];
stack<int> s;
int color[maxn];
int t,n;
void dfs_visit(int u)
{
    color[u]=GRAY;
    d[u]=++t;
    for(int v=1;v<=n;v++)
    {
        if(g[u][v]==0) continue;
        if(color[v]==WHITE)
            dfs_visit(v);
    }
    color[u]=BLACK;
    f[u]=++t;
}
void dfs()
{
    for(int u=1;u<=n;u++)
        color[u]=WHITE;
    for(int u=1;u<=n;u++)
    {
        if(color[u]==WHITE)
            dfs_visit(u);
    }
    for(int u=1;u<=n;u++)
        printf("%d %d %d\n",u,d[u],f[u]);
}
int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        int u,k;
        scanf("%d%d",&u,&k);
        for(int j=1;j<=k;j++)
        {
            int v;
            scanf("%d",&v);
            g[u][v]=1;
        }
    }
    dfs();
    return 0;
}

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

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

int M[N][N] = {0}, color[N] = {0}, d[N], f[N], tt = 0, n;

void dfs_visit(int u) {
  int v;
  color[u] = GRAY;
  d[u] = ++tt;
  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;
}

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

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

int main(void) {
  int u, v, k, i, j;

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

  return 0;
}

C++: #include <vector>
#include <iostream>
#include <set>
#include <cstdio>
#include <queue>
#include <cstdio>
#include <cstdlib>
#include <cassert>
#include <ctime>
#include <cmath>
#include <complex>
#include <algorithm>
#include <tuple>
#include <algorithm>
#include <limits>
#include <map>

using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;

int d[110], f[110];
vector<int> g[110];
int t;
bool used[110];
void solve(int i) {
    if (used[i]) return;
    used[i] = true;
    t++;
    d[i] = t;
    for (int j: g[i]) {
        solve(j);
    }
    t++;
    f[i] = t;
}

int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        int id, u;
        cin >> id >> u;
        for (int j = 0; j < u; j++) {
            int a;
            cin >> a;
            g[i].push_back(a-1);
        }
    }
    t = 0;
    fill_n(used, 110, false);
    for (int i = 0; i < n; i++) {
        solve(0);
    }
    for (int i = 0; i < n; i++) {
        printf("%d %d %d\n", i+1, d[i], f[i]);
    }
    return 0;
}