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 <cstdio>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <queue>
#include <stack>
#include <cstring>
using namespace std;

bool A[110][110],flag[110];
int in[110],out[110];
int n,now=1;
stack<int> S;

void dfs_visit(int u){
	flag[u]=true;
	for(int i=1;i<=n;i++){
		if(A[u][i]==true && flag[i]==false) {
			S.push(i);
			in[i]=now++;
			dfs_visit(i);
		}
	}
	int x=S.top();
	S.pop();
	out[x]=now++;
	return ;
}

void dfs(){
	S.push(1);in[1]=now++;
L1:	while(S.empty()==0){
		int x=S.top();
		dfs_visit(x);
	}
	for(int i=1;i<=n;i++){
		if(flag[i]==false){
			S.push(i);in[i]=now++;goto L1;
		}
	}
	for(int i=1;i<=n;i++) cout<<i<<" "<<in[i]<<" "<<out[i]<<endl;
	return ;
}

int main (){
	int a,b,c;
	cin>>n;
	for(int i=1;i<=n;i++){
		flag[i]=false;
			for(int j=1;j<=n;j++){
				A[i][j]=false;
		}
	}
	for(int i=1;i<=n;i++){
		cin>>a>>b;
		for(int j=1;j<=b;j++){
			cin>>c;
			A[a][c]=true;
		}
	}
	dfs();
	return 0;

}

C++: #include <iostream>
#include <stack>
using namespace std;
#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;
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;
    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(void){
    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<bits/stdc++.h>
using namespace std;
const int MAXN =  100+7;
struct node {
    int id;
    node* next;
};
node* g[MAXN];
bool visit[MAXN];
int d[MAXN];
int f[MAXN];
int mytime;
stack<int> s;
void dfs(int i){
    node* p = g[i];
    while(p->next!=NULL){
        p=p->next;
        if(visit[p->id]==false){
            s.push(p->id);
            mytime++;
            d[p->id] = mytime;
            visit[p->id] = true;
            dfs(p->id);
        }

    }
    s.pop();
    mytime++;
    f[i] = mytime;

}
int main() {
//    freopen("../in.txt", "r", stdin);
    memset(visit, false, sizeof(visit));
    int n;
    scanf("%d", &n);
    int i;
    for(i = 1; i <= n; i++) {
        g[i] = (node*)malloc(sizeof(node));
        g[i]->next = NULL;
    }
    for(i = 0; i < n; i++) {
        int num;
        int k;
        scanf("%d", &num);
        scanf("%d", &k);
        int j;
        for(j = 0; j < k; j++) {
            int r;
            scanf("%d", &r);
            node* t = (node*)malloc(sizeof(node));
            t->id = r;
            t->next = NULL;
            node* p = g[num];
            while(p->next != NULL) p = p->next;
            p->next = t;
        }
    }
    mytime = 0;
    while(true){
        int u;
        int g = -1;
        for(u = 1; u <= n; u++){
            if(visit[u]==false){
                g = u;
                break;
            }
        }
        if(g==-1){
            break;
        }
        s.push(g);
        mytime++;
        d[g] = mytime;
        visit[g] = true;
        dfs(g);
    }

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

C++: #include <bits/stdc++.h>
#define rep(i, a, b) for (int i = a; i < (b); i++)
#define rrep(i, a, b) for (int i = a; i >= (b); i--)
#define all(x) (x).begin(), (x).end()
using namespace std;
using ll = long long;
using P = pair<int, int>;
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;
}
const int INF = 2e9;
const int MOD = 1e9 + 7;

int main() {
   int n;
   cin >> n;
   vector<vector<int>> to(n);
   rep(i, 0, n) {
      int u, k;
      cin >> u >> k;
      u--;
      rep(j, 0, k) {
         int v;
         cin >> v;
         v--;
         to[u].push_back(v);
      }
   }
   vector<int> d(n), f(n), color(n);
   int t = 0;
   function<void(int)> dfs = [&](int u) {
      if (color[u] != 0) return;
      color[u] = 1;
      d[u] = ++t;
      for (int i = 0; i < to[u].size(); i++) {
         if (color[to[u][i]] == 0) {
            dfs(to[u][i]);
         }
      }
      color[u] = 2;
      f[u] = ++t;
   };
   rep(i, 0, n) dfs(i);
   rep(i, 0, n) printf("%d %d %d\n", i + 1, d[i], f[i]);
   return 0;
}