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) doesAllAdjsVisited(vertices []vertex) bool {
	for _, vId := range v.adjs {
		adj := vertices[vId-1]
		if !adj.isVisited() {
			return false
		}
	}
	return true
}

func (v *vertex) isFirstVisit() bool {
	return v.firstVisitAt == 0
}

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

func (v *vertex) nextVertex(vertices []vertex) (vertexId, error) {
	for _, vId := range v.adjs {
		adj := vertices[vId-1]
		if !adj.isVisited() {
			return vId, nil
		}
	}
	return vertexId(-1), fmt.Errorf("illegal")
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	timestamp = timestamp + 1
	currentVertex := &vertices[currentId-1]
	if currentVertex.isFirstVisit() {
		currentVertex.firstVisitAt = timestamp
	}
	for !currentVertex.doesAllAdjsVisited(vertices) {
		nextVertexId, _ := currentVertex.nextVertex(vertices)
		timestamp = dfs(nextVertexId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

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)
	}

	dfs(vertexId(1), 0, 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 <algorithm>
#include <bitset>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;

void dfs(const vector<vector<int>>& edges, vector<int>& ds, vector<int>& fs, int u, int& t) {
    if (ds[u] > 0) {
        return;
    }
    ds[u] = ++t;
    for (auto v : edges[u]) {
        dfs(edges, ds, fs, v, t);
    }
    fs[u] = ++t;
}

int main() {
    int n;
    cin >> n;
    vector<vector<int>> edges(n);
    for (int i = 0; i < n; i++) {
        int u, k;
        cin >> u >> k;
        u--;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            v--;
            edges[u].push_back(v);
        }
        sort(begin(edges[u]), end(edges[u]));
    }
    vector<int> ds(n, -1);
    vector<int> fs(n, -1);
    int t = 0;
    for (int i = 0; i < n; i++) {
        dfs(edges, ds, fs, i, t);
    }
    for (int i = 0; i < n; i++) {
        cout << i + 1 << " " << ds[i] << " " << fs[i] << endl;
    }
}

C++: #include <iostream>

using namespace std;

	int TIME = 0;
	int d[101];
	int f[101];
	int num;
	int graph[101][101] = {0};

void dfs(int x){
	TIME++;
	d[x] = TIME;

	for(int i=1;i<=num;i++){
		if(graph[x][i] == 1 && d[i]==0){
			printf("%d -> %d\n",x,i);
			dfs(i);
		}
	}
	f[x] = ++TIME;
}

int main(){
	int hon;
	int eda;
	int ver;

	cin>>num;
	for(int i=0;i<num;i++){
		cin>>eda;
		cin>>hon;
		for(int j=0;j<hon;j++){
			cin>>ver;
			graph[eda][ver]++;
		}
	}

	dfs(1);

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

	return 0;
}

C++: #include <iostream>

using namespace std;

int V[100][100];
int n;

int d[100];
int f[100];

int t = 1;
void dfs(int src){
  t++;
  for(int i=1;i<=n;i++){
    if(V[src][i] != 0 && !d[i]){
      d[i] = t;
      dfs(i);
      t++;
    }
  }
  f[src] = t;
}
int main(){
  int  src, dst, num, non_visited;
  cin >> n;
  for(int i=1;i<=n;i++){
    d[i] = 0; f[i] = 0;
  }
  for(int i=1;i<=n;i++){
    cin >> src >> num;
    for(int j=0;j<num;j++){
      cin >> dst;
      V[src][dst] = 1;
    }
  }
  non_visited = 1;
  do{
    d[non_visited] = t;
    dfs(non_visited);
    non_visited = 0;
    for(int i=1;i<=n;i++){
      if(!d[i]){
        non_visited = i;
        break;
      }
    }
    t++;
  }while(non_visited);

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

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

int G[110][110];///构造图
bool vis[110];///设置是否访问过
int tot;///设置访问次序
int st[110],ed[110];///设置顶点的发现时刻，顶点的结束时刻
int n;

int next_(int u){
    for(int i=1;i<=n;i++){
        if(G[u][i]&&vis[i]==0)
            return i;
    }
    return -1;
}

void DFS(int r){
    stack<int> s;
    s.push(r);
    vis[r]=true;
    st[r]=++tot;
    while(!s.empty()){
        int u=s.top();
        int v=next_(u);
        if(v!=-1){
            if(vis[v]==false){
                vis[v]=true;
                st[v]=++tot;
                s.push(v);
            }
        }
        else{
            s.pop();
            ed[u]=++tot;
        }

    }
}

void DFS_Visit(){
    memset(st,0,sizeof(st));
    memset(ed,0,sizeof(ed));
    memset(vis,0,sizeof(vis));
    tot=0;
    for(int i=1;i<=n;i++){
        if(vis[i]==false)
            DFS(i);
    }
    for(int i=1;i<=n;i++){
        printf("%d %d %d\n",i,st[i],ed[i]);
    }
}

int main(){
    scanf("%d",&n);
    memset(G,0,sizeof(G));

    for(int i=0;i<n;i++){
        int u,k;
        scanf("%d%d",&u,&k);
        for(int j=0;j<k;j++){
            int v;
            scanf("%d",&v);
            G[u][v]=1;
        }
    }
    DFS_Visit();
    return 0;
}

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

using namespace std;

struct Node {
    int visit = 0;
    vector<int> next;
    int s = 0;
    int start = 0;
    int end = 0;
};

int main() {
    int n, id, k, temp, time = 1;
    Node node[101];
    stack<int> st;

    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> id >> k;
        for (int j = 0; j < k; j++) {
            cin >> temp;
            node[id].next.push_back(temp);
        }
    }

    while (1) {
        int s = -1;
        for (int i = 1; i <= n; i++) {
            if (node[i].visit == 0) {
                s = i;
                break;
            }
        }
        if (s == -1) {
            break;
        }
        
        node[s].start = time++;
        st.push(s);
        while (!st.empty()) {
            temp = st.top();
            if (node[temp].s < node[temp].next.size()) {
                if (node[node[temp].next[node[temp].s]].visit == 0) {
                    node[node[temp].next[node[temp].s]].start = time++;
                    node[node[temp].next[node[temp].s]].visit = 1;
                    st.push(node[temp].next[node[temp].s++]);
                }
                else {
                    node[temp].s++;
                }
            }
            else {
                node[temp].visit = 2;
                node[temp].end = time++;
                st.pop();
            }
        }
    }

    for (int i = 1; i <= n; i++) {
        cout << i << " " << node[i].start << " " << node[i].end << endl;
    }

    return 0;
}