Go: package main

import "fmt"

type node struct {
	id, d, v int
	adj      []node
}

var n int
var seen []bool
var graph []node

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func dfs(v, t int) int {
	// fmt.Printf("dfs(v %d, t %d) en:\n", v, t)
	seen[v] = true
	graph[v].v = t
	tt := t
	for _, vv := range graph[v].adj {
		if !seen[vv.id] {
			tt = max(tt, dfs(vv.id, tt+1))
		}
	}
	graph[v].d = tt + 1
	// fmt.Printf("dfs(v %d, t %d) ex: d %d\n", v, t, graph[v].d)
	return graph[v].d
}

func main() {
	fmt.Scan(&n)
	graph = make([]node, n+1)
	for i := 1; i <= n; i++ {
		var u, k, v int
		fmt.Scan(&u, &k)
		graph[u].id = u
		// 頂点uはk個の隣接頂点を持っている
		for j := 0; j < k; j++ {
			fmt.Scan(&v)
			var t node
			t.id = v
			graph[u].adj = append(graph[u].adj, t)
		}
	}
	// fmt.Println("n", n, "graph", graph)
	seen = make([]bool, n+1)
	// t := dfs(1, 1)
	v, t := 1, 1
	done := false
	for !done {
		tt := dfs(v, t)
		done = true
		for i := range seen {
			if !seen[i] {
				done = false
				v = graph[i].id
				t = tt
				break
			}
		}
	}
	for i := 1; i <= n; i++ {
		fmt.Printf("%d %d %d\n", i, graph[i].v, graph[i].d)
	}
}

C++: #include <iostream>
#include <set>
#include <vector>
#include <queue>
#include <stack>
#include <utility>

using namespace std;

typedef long long signed int ll;

constexpr ll NIL = -20000000000;

int g[101][101],n,d[101],f[101];

int main() {
    cin >> n;
    for(int i = 0;i < n;i++) {
        int u,k,v;
        cin >> u >> k;
        for(int j = 0;j < k;j++) {
            cin >> v;
            g[u][v]++;
        }
    }
    stack<int> dfs;
    int time = 1;
    dfs.push(1);
    d[1] = time;
    while(!dfs.empty()){
        int u = dfs.top();
        bool flag = false;
        for(int i = 1;i <= n;i++){
            if(g[u][i] && d[i] == 0) {
                dfs.push(i);
                time++;
                d[i] = time;
                flag = true;
            }
        }
        if(!flag){
            dfs.pop();
            time++;
            f[u] = time;
        }
    }
    for(int i = 1;i <=n;i++) {
        cout << i << " " << d[i] << " " << f[i] <<endl;
    }
}

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

int G[101][102];
int found[101];
int comp[101];   // complete.
int t;  // time.

typedef struct box{ int val; box* next; } box_t;  // stack.

box_t* init()
{
    box_t* head = new box_t;
    head->val = -1;
    head->next = NULL;
    return head;
}

bool isEmpty(box_t* head){ return (head->next == NULL ? true : false); }

box_t* push(box_t* head, int data)
{
    box_t* box = new box_t;
    box->val = data;
    box->next = head->next;
    head->next = box;
    return box;
}

int pop(box_t* head)
{
    if(isEmpty(head)){ return -1; }
    box_t* box = head->next;
    int val;
    head->next = box->next;
    val = box->val;
    delete box;
    return val;
}

int front(box_t* head)
{
    int val;
    if(isEmpty(head)){ return -1; }
    val = head->next->val;
    return val;
}

box_t* stack = init();

void search_loop(int i)
{
    int j, k;
    while(1){
        if(found[i] == 0){
            t++; found[i] = t;
            push(stack, i);
        }
        for(k = G[i][0]; G[i][k] != 0 && found[G[i][k]] != 0; k++);
        if(G[i][k] == 0){
            if(isEmpty(stack)){ return; }
            else{
                j = pop(stack);
                t++; comp[j] = t;
                i = front(stack);
            }
        }else{
            G[i][0] = k + 1;
            i = G[i][k];
        }
    };
    return;
}

int main()
{
    int n, i, j, a, b, e;
    cin >> n;
    for(i = 1; i <= n; i++){
        G[i][0] = 1;
        for(j = 1; j <= n + 1; j++){ G[i][j] = 0; } }

    for(i = 1; i <= n; i++){
        cin >> a >> e;
        for(j = 1; j <= e; j++){
            cin >> b; G[a][j] = b; } }  // adjacent representation.

    for(i = 1; i <= n; i++){ found[i] = 0; comp[i] = 0; }
    t = 0;
    while(1){
        for(i = 1; i <= n; i++){
            if(found[i] == 0) break;
        }
        if(i > n) break;
        search_loop(i);
    };

    for(i = 1; i <= n; i++){
        cout << i << " " << found[i] << " " << comp[i] << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <vector>
#define N 2000

using namespace std;
vector<vector<int> > pa;
vector<vector<int> > ch;
int first[N] = {0};
int second[N] = {0};
int timestamp = 0;
void dfs(int x) {
    if (ch[x].empty()) {
        return;
    } else {
        for (int i = 0; i < ch[x].size(); i++) {
            if (first[ch[x][i]] * second[ch[x][i]] == 0) {
                timestamp++;
                first[ch[x][i]] = timestamp;
                dfs(ch[x][i]);
                timestamp++;
                second[ch[x][i]] = timestamp;
            }
        }
        return;
    }
}
int main() {
    int n;
    cin >> n;
    int temp = n;
    pa.clear(); pa.resize(N + 5);
    ch.clear(); ch.resize(N + 5);
    while (temp--) {
        int u, k, v;
        cin >> u >> k;
        for (int i = 0; i < k; i++) {
            cin >> v;
            pa[v].push_back(u);
            ch[u].push_back(v);
        }
    }
    int an = 0;
    for (int i = 1; i <= n; i++) {
        if (pa[i].empty()) {
            an = i;
        } else {
            sort(pa[i].begin(), pa[i].end(), less<int>());
        }
        if (ch[i].empty()) {
            ;
        } else {
            sort(ch[i].begin(), ch[i].end());
        }
    }
    timestamp++;
    first[an] = timestamp;
    dfs(an);
    timestamp++;
    second[an] = timestamp;
    for (int i = 1; i <= n; i++) {
        cout << i << ' ' << first[i] << ' ' << second[i] << '\n';
    }
}

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, Adj[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 (Adj[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() {
	
	int  u, k, v;
	cin >> n;

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