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++: // Ref : https://book.mynavi.jp/ec/products/detail/id=35408

#include <iostream>
using namespace std;

static const int N = 100;
int G[N][N] = { {} };
int n, time = 0;
int detected_t[N] = {};
int finished_t[N] = {}; 

void depthFirstSearch(int ix) {
	if (!detected_t[ix - 1]) {
		detected_t[ix - 1] = ++time;
		for (int j = 0; G[ix - 1][j]; j++) {
			depthFirstSearch(G[ix - 1][j]);
		}
		if (!finished_t[ix - 1]) finished_t[ix - 1] = ++time;
	}
}

void myCheck() {
	for (int i = 0; i < n; i++) {
		cout << "index " << i + 1 << " : ";
		for (int j = 0; G[i][j]; j++) {
		if (j) cout << " ";
		cout << G[i][j];
		}
		cout << " time " << detected_t[i] << ", " << finished_t[i] << endl;
	}
}

int main() {
	int ix, deg;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> ix >> deg;
		for (int j = 0; j < deg; j++) cin >> G[ix - 1][j];
	}

	depthFirstSearch(1);
	//myCheck();

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

	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int n,lis[111][111]={},d[111]={},f[111],t=1;

void dfs(int now){
  d[now]=t++;
  for(int i=1;i<=n;i++)
    if(lis[now][i]&&d[i]==0)dfs(i);
  f[now]=t++;
}

int main(){
  cin>>n;
  for(int c=0;c<n;c++){
    int u,k,v;
    cin>>u>>k;
    for(int i=0;i<k;i++){
      cin>>v;
      lis[u][v]=1;
    }
  }
  for(int i=1;i<=n;i++)if(d[i]==0)dfs(i);
  for(int i=1;i<=n;i++)cout<<i<<" "<<d[i]<<" "<<f[i]<<endl;  
  
  return 0;
}

C++: // http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_11_C
#include <iostream>
#include <cstdio>
#include <queue> // 入れた順番に出していく玉突き構造。
using namespace std;

int G[110][110];
int n;
int u, k, v;

/* void print_matrix(int N) {
  for(int i=0; i<N; i++) {
    for(int j=0; j<N; j++) {
      printf("%d", G[i][j]);
      if (j < N-1) {
	printf(" ");
      }
    }
      printf("\n");
  }
} */

void make_matrix() {
  fill(&G[0][0], &G[0][0]+110*110, 0);
  scanf("%d", &n);
  for (int i=0; i<n; i++) {
    scanf("%d%d", &u, &k);
    u--;
    for (int j=0; j<k; j++) {
      scanf("%d", &v);
      v--;
      G[u][v] = 1;
    }
  }
}

int timer = 1; // timeだとエラーが出たので。
int d[110]; // 訪問時刻。ナマの数字を入れる。
int f[110]; // 終了時刻。ナマの数字を入れる。

void init() {
  fill(d, d+110, -1);
  fill(f, f+110, -1);
}

void dfs(int cur) { // curを訪問。
  d[cur] = timer;
  timer++;
  // cerr << "visiting " << cur << " at the time " << timer << endl;
  for (int i=1; i<=n; i++) { // 節点i
    if (G[cur-1][i-1] == 1 && d[i] == -1) {
      dfs(i);
    }
  }
  f[cur] = timer;
  timer++;
}

int main() {
  make_matrix();
  init();
  for (int i=1; i<=n; i++) {
    if (d[i] == -1) {
      dfs(i);
    }
  }
  for (int i=1; i<=n; i++) {
    printf("%d %d %d\n", i, d[i], f[i]);
  }
}

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

using namespace std;

int  n, M[100][100], d[100], f[100], color[100], tt, nt[100], W = 0, G = 1, B = 2;

int next (int u) {

    int v;
    for (v = nt[u]; v < n; v++) {
        nt[u] = v + 1;
        if (M[u][v] != 0) {
            return v;
        }
    }
    return -1;

}

void dfs_visit (int r) {

    int i, u, v;

    for (i = 0; i < n; i++) {
        nt[i] = 0;
    }

    stack<int> S;
    S.push(r);
    color[r] = G;
    d[r] = ++tt;

    while (!S.empty()) {
        u = S.top();
        v = next (u);
        if (v != -1) {
            if (color[v] == W) {
                color[v] = G;
                d[v] = ++tt;
                S.push(v);
            }
        } else {
            S.pop();
            color[u] = B;
            f[u] = ++tt;
        }
    }

}

void dfs () {

    int i, u;

    for (i = 0; i < n; i++) {
        color[i] = W;
        nt[i] = 0;
    }
    time = 0;

    for (u = 0; u < n; u++) {
        if (color[u] == W) {
            dfs_visit(u);
        }
    }

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

}

int main () {

    int u, k, v, i, j;

    cin >> n;
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            M[i][j] = 0;
        }
    }

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

    dfs ();

    return 0;

}

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

#define MAX 105

struct Point{
    int id;
    int d;
    int f;
    bool flag;
    std::vector<int> child;
};

int stack[MAX];
int sp = 0;
int count = 1;

Point p[MAX];

void push(int id){
    if(p[id].flag == false){
        stack[sp++] = id;
        p[id].d = count++;
        p[id].flag = true;
    }
}

void pop(){
    p[stack[--sp]].f = count++;
    //return stack[sp];
}

void dft(int id){
    //std::cout << id << "に対しdft\n";
    push(id);
    int size = p[id].child.size();
    for(int i=0;i<size;i++){
        if(p[p[id].child[i]].flag == false){
            dft(p[id].child[i]);
        }
    }
    pop();
}

int main(){
    int n;
    int size;
    std::cin >> n;
    for(int i=1;i<=n;i++){
        std::cin >> p[i].id >> size;
        for(int j=0;j<size;j++){
            int tmp;
            std::cin >> tmp;
            p[i].child.push_back(tmp);
        }
    }
    for(int i=1;i<=n;i++){
        if(p[i].flag == false){
            dft(i);
        }
    }
    
    for(int i=1;i<=n;i++){
        std::cout << p[i].id << ' ' << p[i].d << ' ' << p[i].f << '\n';
    }
    
    return 0;
}