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 <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i=0; i < (int)(n); i++)
using ull = unsigned long long;
using ll = long long;

vector<vector<int>> G(101);
int d[101] = {}, f[101] = {};

void dfs(int from, int& time) {
    if (d[from] == -1) {
        time++;
        d[from] = time;

        for (auto v: G[from]) dfs(v, time);

        time++;
        f[from] = time;
    }
}

int main() {
    int N;
    cin >> N;
    
    rep(i, N) {
        int u, k, vj;
        cin >> u >> k;
        rep(j, k) {
            cin >> vj;
            G[u].push_back(vj);
        }
    }

    int time=0;
    rep(i, N+1) d[i] = -1;
    for (int i=1; i<=N; i++) {
        if (d[i] == -1) dfs(i, time);
    }
    
    for (int i=1; i<=N; i++) {
        cout << i << " " << d[i] << " " << f[i] << endl;
    }

    return 0;
}

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

static const int DFS_VISIT_NO   = 0;
static const int DFS_VISIT_NOW  = 1;
static const int DFS_VISIT_DONE = 2;

static int g_time = 0;
static int g_setime[100][2] = {0};

void DfsVisit(vector<int> &graph, int node, vector<int> &state)
{
    int i;
    int nnum;
    int target;

    ++g_time;
    g_setime[node][0] = g_time;

    state[node] = DFS_VISIT_NOW;
    
    nnum = graph[node].size();

    for (i = 0; i < nnum; i++) {
        target = graph[node][i];
        if (state[target] != DFS_VISIT_DONE) {
            DfsVisit(graph, target, state);
        }
    }

    state[node] = DFS_VISIT_DONE;

    ++g_time;
    g_setime[node][1] = g_time;

    return;
}


void DFS(vector<int> &graph, int num)
{
    int i;
    vector<int> state;

    for (i = 0; i < num; i++) {
        state[i] = DFS_VISIT_NO;
    }

    for (i = 0; i < num; i++) {
        if (state[i] == DFS_VISIT_NO) {
            DfsVisit(graph, num, i, state);
        }
    }

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

    return;
}

int main(void)
{
    int i, j;
    int target, tnum, node;
    int num;

    scanf("%d", &num);
    vector<int> graph[num];

    for (i = 0; i < num; i++) {
        scanf("%d" "%d", &target, &tnum);
        --target;
        for (j = 0; j < tnum; j++) {
            scanf("%d", &node);
            --node;
            graph[target].push_back(node);
        }
    }

    DFS(graph, num);
}

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


using namespace std;


stack<int> visiting;

#define MAX 100
bool adj[MAX + 2][MAX + 2];
int d[MAX + 1], f[MAX + 1];
bool discovered[MAX + 1];
int tt, n;


void dfs(int v)
{
    visiting.push(v);
    discovered[v] = true;
    d[v] = ++tt;

    while (!visiting.empty()) {
        int now = visiting.top();
        int i;
        for (i = 1; i <= n; i++) {
            if (adj[now][i] && !discovered[i])
                break;
        }

        if (!discovered[i] && i <= n) {
            d[i] = ++tt;
            visiting.push(i);
            discovered[i] = true;
        } else {
            f[now] = ++tt;
            visiting.pop();
        }
    }
}


int main()
{
    cin >> n;
    for (int i = 1; i <= n; i++) {
        int id, k;
        cin >> id >> k;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            adj[id][v] = true;
        }

        discovered[i] = false;
    }

    for (int i = 1; i <= n; i++)
        if (!discovered[i])
            dfs(i);


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

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
int n;
bool ok[10005];
int d[10005];
int f[10005];
vector<int> e[10005];
int step=0;
void dfs(int i){
	ok[i]=1;
	step++;
	d[i]=step;
	for(int j=0;j<e[i].size();j++)
		if(!ok[e[i][j]])
			dfs(e[i][j]);
	step++;
	f[i]=step;
}
void solve(){
	for(int i=1;i<=n;i++)if(!ok[i])dfs(i);
	for(int i=1;i<=n;i++)
		cout<<i<<' '<<d[i]<<' '<<f[i]<<"\n";
}
int main(){
//	freopen("a.txt","r",stdin);
	cin>>n;
	int u,k,v;
	for(int i=1;i<=n;i++){
		cin>>u>>k;
		for(int j=0;j<k;j++)cin>>v,e[u].push_back(v);
	}
	solve();
	return 0;
}

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() || result[0][G[next - 1].begin()->to - 1]){
				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());
				if(tmp != next)
					prev[tmp - 1] = next;
				next = tmp;
			}
			//cout << next << endl;
		}
	}
	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;
}