Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

// repr state of visited node
// WHITE yet visit
// GEAY  visiting
// BLACK visited
const (
	WHITE int = iota
	GRAY
	BLACK
)

type dfsGraph struct {
	g      [][]int
	colors []int
	stime  []int // Start time of visiting node
	ftime  []int // Finish time of visiting node
}

var time int

func makeAdjList() [][]int {
	var n int
	fmt.Scanf("%d", &n)

	adj := make([][]int, n)
	for i := 0; i < n; i++ {
		adj[i] = make([]int, n)
	}

	sc := bufio.NewScanner(os.Stdin)
	for i := 0; i < n; i++ {
		sc.Scan()
		nodeInfo := strings.Split(sc.Text(), " ")
		outDegree, _ := strconv.Atoi(nodeInfo[1])

		if outDegree > 0 {
			for k := 0; k < outDegree; k++ {
				j, _ := strconv.Atoi(nodeInfo[k+2])
				j-- // convert 1 based to 0 based
				adj[i][j] = 1
			}
		}
	}

	return adj
}

func (dg dfsGraph) dfsVisit(u int) {
	// 頂点uを訪問中に設定
	dg.colors[u] = GRAY
	time++
	dg.stime[u] = time

	// uの隣接nodeを訪問
	for v := 0; v < len(dg.g); v++ {
		if dg.g[u][v] == 0 {
			continue // 辺がなければスキップ
		}

		// vが未訪問なら訪問
		if dg.colors[v] == WHITE {
			dg.dfsVisit(v)
		}
	}

	// 頂点uを訪問済みに設定
	dg.colors[u] = BLACK
	time++
	dg.ftime[u] = time
}

func (dg dfsGraph) dfs() {
	for i := 0; i < len(dg.g); i++ {
		if dg.colors[i] == WHITE {
			dg.dfsVisit(i)
		}
	}
}

func (dg dfsGraph) printDfsTime() {
	for i := 0; i < len(dg.g); i++ {
		fmt.Printf("%d %d %d\n", i+1, dg.stime[i], dg.ftime[i])
	}
}

func main() {
	adj := makeAdjList()
	colors := make([]int, len(adj))
	stime := make([]int, len(adj))
	ftime := make([]int, len(adj))
	graph := dfsGraph{adj, colors, stime, ftime}
	graph.dfs()
	graph.printDfsTime()
}

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

using namespace std;
int d[100] = {}, f[100] = {}, ans[100][100] = {};
int now = 1, n;
int dfs(int i) {
	d[i] = now;
	++now;
	for (int u = 0; u < n; ++u) {
		if (ans[i][u] == 1 && d[u] == 0) {
			dfs(u);
		}
	}
	f[i] = now;
	++now;
	return 0;
}
int main() {
	int u, k, tmp, now=0;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		cin >> u >> k;
		for (int j = 0; j < k; j++)
		{
			cin >> tmp;
			ans[u - 1][tmp - 1] = 1;
		}
	}
	/*
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j < n;++j) {
			cout << ans[i][j] << " ";
		}
		cout << endl;
	}
	*/
	for (int i = 0; i < n; ++i) {
		if (d[i] == 0) {
			dfs(i);
		}
	}
	for (int i = 0; i < n; i++)
	{
		cout << i+1 << " " << d[i] << " " << f[i] << endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n, M[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 (M[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++) 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 <iostream>
using namespace std;

int n;
int v[100][100];
int d[100], f[100], r[100];

void stamp(int id, int t) {
	if (t > 2 * n)
		return;

	if (d[id - 1] == 0) {
		d[id - 1] = t;
		int i = 0;
		while (v[id - 1][i] == 0)
			i++;
		if (i < n && d[i] == 0)
			stamp(i + 1, t + 1);
		else
			stamp(id, t + 1);
	}
	else if (f[id - 1] == 0) {
		int i;
		for(i = 0; i < n; i++)
			if (v[id - 1][i] == 1 && d[i] == 0) {
				stamp(i + 1, t);
				break;
			}
		if (i > n - 1) {
			f[id - 1] = t;
			int j1 = 0, ct = 0;
			for (int j = 0; j < n; j++){
				if (v[j][id - 1] == 1 && f[j] == 0 && d[j] != 0) {
					ct++;
					if(ct == 1 || d[j] == d[id - 1] - 1)
						j1 = j;
				}
			}
			if(j1 < n)
				stamp(j1 + 1, t + 1);

			int k = 0;
			while (d[k] != 0)
				k++;
			if (k < n)
				stamp(k + 1, t + 1);
		}
	}	
	return;
}

int main()
{
	cin >> n;

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

	for (int i = 0; i < n; i++)
		for (int j = 0; j < n; j++)
			v[i][j] = 0;

	for (int i = 0; i < n; i++) {
		int u, k, s;

		cin >> u >> k;

		for (int j = 0; j < k; j++) {
			cin >> s;
			v[u - 1][s - 1] = 1;
		}
	}

	stamp(1, 1);

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

	return 0;
}

C++: #include <bits/stdc++.h>

#define rep(i, a, b) for (int i = a; i < (int)(b); ++i)
#define rrep(i, a, b) for (int i = b - 1; i >= (int)(a); --i)

using namespace std;

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;

void dfs(const vvi& g, vector<bool>& seen, vi& d, vi& f, int& t, int v) {
    stack<int> st;
    st.push(v);
    d[v] = t++;
    seen[v] = true;

    while (!st.empty()) {
        int v = st.top();

        bool finished = true;
        for (auto itr = g[v].begin(); itr != g[v].end(); ++itr) {
            if (!seen[*itr]) {
                seen[*itr] = true;
                d[*itr] = t++;
                st.push(*itr);
                finished = false;
                break;
            }
        }

        if (finished) {
            st.pop();
            f[v] = t++;
        }
    }
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n;
    cin >> n;

    vvi g(n);
    rep(i, 0, n) {
        int u, k;
        cin >> u >> k;

        rep(j, 0, k) {
            int v;
            cin >> v;
            g[u - 1].push_back(v - 1);
        }
    }

    int t = 1;

    vi d(n), f(n);
    vector<bool> seen(n, false);

    rep(i, 0, n) {
        if (!seen[i]) { dfs(g, seen, d, f, t, i); }
    }

    rep(i, 0, n) { cout << i + 1 << " " << d[i] << " " << f[i] << endl; }

    return 0;
}

C++: 
#include <iostream>
#include <cstdio>
#include <queue>
#define rep(i,n) for(int i = 0;i<n;i++)
using namespace std;


vector<int> G[105];
int d[105];
int f[105];
int tm = 1;
void dfs(int p){
    d[p]=tm;
    rep(i,G[p].size()){
        if(d[G[p][i]]==-1){
            tm++;
            dfs(G[p][i]);
        }
    }
    f[p] = ++tm;
    return;
}
int main(int argc, const char * argv[])
{
    int n;
    cin >> n;
    for(int i = 0;i <= n;i++) {
        d[i]=-1;
        f[i]=-1;
    }
    for(int i = 0;i < n;i++){
        int u,k;
        int to;
        scanf("%d %d",&u,&k);
        for(int j=0;j<k;j++){
            scanf("%d",&to);
            G[u].push_back(to);
        }
    }
    dfs(1);
    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;
}