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;
typedef long long ll;
const ll MOD = 1e9 + 7;
const int inf = 1e9;
const ll INF = 1e18;
const double pi = 3.14159265358979323846;
#define rep(i, n) for (int i = 0; i < n; i++)
using Graph = vector<vector<int>>;
using pint = pair<int, int>;
int dx[4] = { 1, 0, -1, 0 }, dy[4] = { 0, 1, 0, -1 };

int n;
vector<int> first, last;
bool seen[100] = {};

void dfs (const Graph& g, int u, int& ptr) {
    first[u] = ptr++;
    seen[u] = 1;
    for (auto next : g[u]) {
        if (seen[next]) continue;
        dfs (g, next, ptr);
    }
    last[u] = ptr++;
}

int main() {
    cin >> n;
    Graph g (n);
    first.resize (n);
    last.resize (n);
    rep (i, n) {
        int a, k;
        cin >> a >> k;
        rep (j, k) {
            int b;
            cin >> b;
            g[a - 1].push_back (b - 1);
            //g[b].push_back (a);
        }
    }
    int ptr = 0;
    rep (i, n) {
        if (first[i] == 0 && last[i] == 0) {
            dfs (g, i, ptr);
        }
    }

    rep (i, n) cout << i + 1 << " " << first[i] + 1 << " " << last[i] + 1 << "\n";
}

C++: #include <bits/stdc++.h>
using namespace std;

#define REP(i,n) for(int i=0;i<n;++i)

const int MAX_N = 100;
int n, t = 0, flag[MAX_N] = {0}, d[MAX_N], f[MAX_N], G[MAX_N][MAX_N] = {0};

void dfs(int u) {
  int v;
  flag[u] = 1;
  d[u] = ++t;
  REP(v, n) {
    if (!G[u][v]) continue;
    if (!flag[v]) dfs(v);
  }
  flag[u] = 2;
  f[u] = ++t;
}

int main() {
  int u, v, k;
  cin >> n;
  REP(i, n) {
    cin >> u >> k;
    REP(j, k) {
      cin >> v;
      G[u - 1][v - 1] = 1;
    }
  }
  REP(i, n) if (!flag[i]) dfs(i);
  REP(i, n) cout << i + 1 << ' ' << d[i] << ' ' << f[i] << endl;
  return 0;
}

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

struct time_check {
    int find_time, end_time;
};

int main() {
    int G[101][101] = {0};
    time_check t[101];

    for (int i = 1; i <= 100; i++) t[i].end_time = 0;

    stack<int> S;
    int n, u, v, k, elapsed=1;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            cin >> v;
            G[u][v] = 1;
        }
    }
    S.push(1);
    t[1].find_time = 1;
    while (! S.empty()) {
        elapsed++;
        u = S.top();
        for (int i = 1; i <= n + 1; i++) {
            if (G[u][i] == 1 && t[i].end_time == 0) {
                t[i].find_time = elapsed;
                G[u][i] = 0;
                S.push(i);
                break;
            }
            if (i == n + 1) {
                t[u].end_time = elapsed;
                S.pop();
            }
        }
    }

    for (int i = 1; i <= n; i++) {
        cout << i << " " << t[i].find_time << " " << t[i].end_time << endl;
    }

    return 0;
}
このコードはWrong Answerです...
理由は以下のコードのl.111のとこのように未訪問の頂点を始点としてdfsしてないから
*/

#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 BRACK = 2;

int n, M[N][N];
int color[N], d[N], f[N], tt;
int nt[N];

// uに隣接するvを番号順に取得
int next(int u) {
    for (int v = nt[u]; v < n; v++) {
        nt[u] = v + 1;
        if (M[u][v]) return v;
    }
    return -1;
}

// スタックを用いた深さ優先探索
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] = BRACK;
            f[u] = ++tt;
        }
    }
}

void dfs() {
    // 初期化
    for (int i = 0; i < n; i++) {
        color[i] = WHITE;
        nt[i] = 0;
    }
    tt = 0;

    // 未訪問のuを始点として深さ優先探索
    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++) 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;

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

int step;
void dfs(int start){
	stack<int> S;
	S.push(start);

	++step;
	d[start]=step;

	while(S.size()){
		int u=S.top();

		int v=0;
		for(int i=1;i<=n;i++){
			if(adj[u][i]==1 && d[i]==0){
				v=i;	break;
			}
		}

		++step;
		if(v==0){
			f[u]=step;
			S.pop();
		}else{
			d[v]=step;
			S.push(v);
		}
	}
}

int main(){
	cin>>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;
			adj[u][v]=1;
		}
	}

	step=0;
	for(int i=1;i<=n;i++){
		if(d[i]==0)dfs(i);
	}

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

	return 0;
}

C++: /**
 * Depth first search.
 * start from node 1
 * 1) increment time 
 * 2) find non visited adjacent node
 * 3) if found move to that node.  d[v'] = time
 * 4) if not found. f[v] = time
 * 5) else end.
 * 5) go to 2.
 */

#include <iostream>
using namespace std;
const int N = 101;
int adj[N][N] = {0};
int d[N]={0};
int f[N]={0};
int t = 1;

void dfs(int n) {
	d[n]=t;
	int k = adj[n][0];
	for (int j=1;j<=k;j++) {
		int nn = adj[n][j];
		if (d[nn]) continue;
		t++;
		dfs(nn);
	}
	f[n]=++t;
}

int main()
{
	int n;
	cin >> n;
	for (int i=1;i<=n;i++){
		int j, k;
		cin >> j >> k;
		adj[j][0]=k;
		for (int m=1;m<=k;m++) {
			int a;
			cin >> a;
			adj[j][m]=a;
		}
	}
	dfs(1);

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

	return 0;
}