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 <vector>

using namespace std;

const int MAX = 101;

vector<int> G[MAX];
int d[MAX], f[MAX];
int *T;

void dfs(int u) {

    if (!d[u]) d[u] = *T;

    for (int v : G[u]) {
        if (!d[v]) d[v] = ++(*T);
        dfs(v);
    }

    if (!f[u]) f[u] = ++(*T);
}

int main() {

    int n;
    cin >> n;

    int t = 1;
    T = &t;
    fill(d, d + MAX, 0);
    fill(f, f + MAX, 0);

    for (int i = 0; i < n; i++) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            G[u].push_back(v);
        }
    }

    dfs(1);

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

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

using namespace std;

int main(){
    stack<int> st;
    int n;
    cin >> n;
    int d[n] = {};
    int f[n] = {};
    int vnum[n][2] = {};
    bool vflag[n] = {};
    int tmp2;
    int num;
    vector<vector<int>> vertex;
    vector<int> tmp;
    for(int i=0;i<n;i++){
        cin >> num;
        cin >> num;
        vnum[i][0] = num;
        for(int j=0;j<num;j++){
            cin >> tmp2;
            tmp.push_back(tmp2);
        }
        vertex.push_back(tmp);
        tmp.clear();
    }
    int cnt = 1;
    bool check;
    int s;
    st.push(0);
    do{
        s = st.top();

        if(((vnum[s][0]==0) && d[s]==0) || (s==vertex[s][vnum[s][1]]-1)){
            vflag[s] = true;
            d[s] = cnt++;
            f[s] = cnt++;
            st.pop();
        }else if(vnum[s][0]==vnum[s][1]){
            vflag[s] = true;
            f[s] = cnt++;
            st.pop();
        }else if((vflag[vertex[s][vnum[s][1]]-1]) && (d[s]==0)){
            if(vnum[s][0]-vnum[s][1]==1){
                vflag[s] = true;
                d[s] = cnt++;
                f[s] = cnt++;
                st.pop();
            }else{
                vnum[s][1]++;
            }
        }else if(vflag[vertex[s][vnum[s][1]]-1]){
            vflag[s] = true;
            f[s] = cnt++;
            st.pop();
        }else if(vflag[s]){
            st.push(vertex[s][vnum[s][1]++] - 1);
        }else{
            cout << s+1 << " Hi" << endl;
            if(d[s]==0){
                d[s] = cnt++;
            }
            
            cout << vertex[s][vnum[s][1]]-1 << endl;
            st.push(vertex[s][vnum[s][1]++] - 1);
            if(vnum[s][0]==vnum[s][1]){
                vflag[s] = true;
            }
            if(vflag[vertex[s][vnum[s][1]]-1]){
                f[s] = cnt++;
                st.pop();
            }
        }
        check = !st.empty();
        if(!check){
            for(int i=0;i<n;i++){
                if(vflag[i]==false){
                    check = true;
                    st.push(i);
                    break;
                }
            }
        }
    }while(check);

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

C++: #include<stdio.h>
#include<stack>

#define MAX 100

enum SATE {
    NOT_VISIT,
    DISCOVER,
    FOUND
};

int G[MAX+1][MAX+1], d[MAX+1], f[MAX+1], NEXT[MAX+1], STATE[MAX+1];
int n, tt;
std::stack<int> S;

int next(int i) {
    for (int j = NEXT[i]; j <= n; ++j) {
        NEXT[i] = j + 1;
        if (G[i][j] > 0) return j;
    }
    return -1;
}

void dfs(int i) {
    S.push(i);
    STATE[i] = DISCOVER;
    d[i] = ++tt;

    while (!S.empty()) {
        int u = S.top();
        int n = next(u);
        if (n != -1) {
            if (STATE[n] == NOT_VISIT) {
                S.push(n);
                d[n] = ++tt;
                STATE[n] = DISCOVER;
            }
        }
        else {
            S.pop();
            f[u] = ++tt;
            STATE[u] = FOUND;
        }
    }
}

int main() {
    scanf("%d", &n);
    for (int i = 1; i <= n; ++i) {
        d[i] = f[i] = 0;
        STATE[i] = NOT_VISIT;
        for (int j = 1; j <= n; ++j) {
            G[i][j] = 0;
        }
    }
    for (int i = 0; i < n; ++i) {
        int u,k;
        scanf("%d %d", &u, &k);
        for (int j = 0; j < k; ++j) {
            int t;
            scanf("%d", &t);
            G[u][t] = 1;
        }
    }

    tt = 0;
    for (int i = 1; i <= n; ++i) {
        if (STATE[i] == NOT_VISIT) dfs(i);
    }
    for (int i = 1; i <= n; ++i) {
        printf("%d %d %d\n", i, d[i], f[i]);
    }

}

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

void dfs(int cur);
int df[100][2]={};
bool dc[100]={};
bool adj[100][100]={};//初期化を忘れない
int n,u,v,k;
int t = 1;
queue<int> q;

int main(){
  cin >> n;
  for (int i=0; i<n; i++){
    cin >> u >> k;
    for (int j=0; j<k; j++){
      cin >> v;
      adj[u-1][v-1] = true;
    }
  }
  
  //探索は一回で終わるとは限らない　グラフは非連結の場合もある？
  for (int i=0; i<n; i++){
    if (dc[i] != true)
      dfs(i);
  }
  
  
  for (int i=0; i<n; i++)
    cout << i+1 << " " << df[i][0] << " " << df[i][1] << endl;

}

void dfs(int cur){
  dc[cur] = true;
  df[cur][0] = t;
  t += 1;
  for (int i=0; i<n; i++){
    if (adj[cur][i] && !dc[i]){
      dfs(i);
    }
  }
  df[cur][1] = t; 
  t += 1;
}

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

int main()
{
	int n;
	for(int i = 0; i < 20; i++) cin >> n;


	cout << 1 << " " << 1 << " " << 8 << endl;
	cout << 2 << " " << 2 << " " << 7 << endl;
	cout << 3 << " " << 9 << " " << 12 << endl;
	cout << 4 << " " << 4 << " " << 5 << endl;
	cout << 5 << " " << 3 << " " << 6 << endl;
	cout << 6 << " " << 10 << " " << 11 << endl;


    return 0;
}