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 <stack>
using namespace std;

enum Color {
	WHITE,
	GRAY,
	BLACK,
};

class dfs {
public:
	dfs(bool matrixT[][100], Color colorT[], int ts_F[], int ts_L[], int verNum) {
		for (int i = 0; i < verNum; i++) {
			for (int j = 0; j < verNum; j++)
				matrixTable[i][j] = matrixT[i][j];
		}
		verNumber = verNum;
	}

	void DFS_Recursive(int nowVerVal) {
		colorTable[nowVerVal] = GRAY;
		++ttl;
		ts_first[nowVerVal] = ttl;

		for (int nextVer = 0; nextVer < verNumber; nextVer++) {
			if (matrixTable[nowVerVal][nextVer] == false) continue;
			if (colorTable[nextVer] != WHITE) continue;
			DFS_Recursive(nextVer);
		}
		colorTable[nowVerVal] = BLACK;
		++ttl;
		ts_last[nowVerVal] = ttl;
	}

	void DFS_InitWithRecursive() {
		ttl = 0;
		for (int i = 0; i < verNumber; i++)
			colorTable[i] = WHITE;

		for (int i = 0; i < verNumber; i++)
			if (colorTable[i] == WHITE) DFS_Recursive(i);
	}

	void DFS_Stack(int firstVerVal) {
		stack<int> stack;
		stack.push(firstVerVal);
		colorTable[firstVerVal] = GRAY;
		++ttl;
		ts_first[firstVerVal] = ttl;

		while (!stack.empty()) {
			int nowVerVal = stack.top();
			int nextVerVal = searchNext(nowVerVal);
			if (nextVerVal != -1) {
				if (colorTable[nextVerVal] == WHITE) {
					colorTable[nextVerVal] = GRAY;
					ts_first[nextVerVal] = ++ttl;
					stack.push(nextVerVal);
				}
			}
			else {
				colorTable[nowVerVal] = BLACK;
				++ttl;
				ts_last[nowVerVal] = ttl;
				stack.pop();
			}
		}
	}

	void DFS_InitWithStack() {
		ttl = 0;
		for (int i = 0; i < verNumber; i++) {
			colorTable[i] = WHITE;
			nextFirstVal[i] = 0;
		}

		for (int i = 0; i < verNumber; i++)
			if (colorTable[i] == WHITE) DFS_Stack(i);
	}

	int searchNext(int nowVerNum) {
		//????????????????????????????????¨????????????????????????
		for (int i = nextFirstVal[nowVerNum]; i < verNumber; i++) {
			nextFirstVal[nowVerNum]++;
			if (matrixTable[nowVerNum][i]) return i;
		}
		return -1;
	}

	void print() {
		for (int i = 0; i < verNumber; i++) {
			cout << i + 1 << " " << ts_first[i] << " " << ts_last[i] << endl;
		}
	}
private:
	bool matrixTable[100][100];
	Color colorTable[100];
	int ts_first[100];
	int ts_last[100];
	int verNumber;
	int ttl;
	int nextFirstVal[100];
};

int main() {
	int verNum; //num??????????????°???value????????????????????????????????¨???
	bool matrixTable[100][100]; //???????????¨??????????????????
	Color colorTable[100];
	int timeStamp_first[100];
	int timeStamp_last[100];
	cin >> verNum;

	for (int i = 0; i < verNum; i++)
		for (int j = 0; j < verNum; j++) {
			matrixTable[i][j] = false;
		}

	for (int i = 0; i < verNum; i++) {
		int verVal, nextVerNum;
		cin >> verVal >> nextVerNum;
		for (int j = 0; j < nextVerNum; j++) {
			int nextVerVal;
			cin >> nextVerVal;
			//0?????????????????´???
			matrixTable[verVal - 1][nextVerVal - 1] = true;
		}
	}

	dfs* d = new dfs(matrixTable, colorTable, timeStamp_first, timeStamp_last, verNum);
	d->DFS_InitWithStack();
	d->print();

	return 0;
}

C++: #include <iostream>
#include <stack>
using namespace std;
const int N = 100;
const int WHITE = 0;
const int GRAY = 1;
const int BLACK = 2;

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

// u?????£??\??????v?????????????????????
int next(int u){
    for (int v = nt[u]; v < n ; v++) {
        nt[u] = v +1;
        if(M[u][v]) return v;
    }
    return -1;
}

//with stack

void dfs_visit (int r){
    for (int i = 0; i < n ; ++i) nt[i] = 0;

    stack<int> S;
    S.push(r);
    color[r] = GRAY;
    tt ++; 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(){
    int u;
    for (u = 0; u < n; ++u) {
        color[u] = WHITE;
    }
    tt = 0;

    for (int u = 0; u < n ; ++u) {
        //????¨???????u????§??????¨????????±???????????¢?´¢
        if(color[u] == WHITE) dfs_visit(u);
    }
    for (int u = 0; u < n ; ++u) {
        cout << u+1 << " " << d[u] << " " << f[u] << endl;
    }
}

int main(){
    int u,v,k;
    
    for (int i = 0; i < n ; ++i) {
        for (int j = 0; j < n ; ++j) {
         M[i][j] = 0;   
        }
    }
    
    cin >> n;
    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,g[100][100],c[100],f[100],e[100],t=1;
void dfs(int now){
  c[now]=1;
  f[now]=t;
  t++;
  for(int i=0;i<n;i++) if(g[now][i]&&c[i]!=1){
      dfs(i);
      t++;
    }
  e[now]=t;
}
int main(){

  int a,b,tmp;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>a>>b;
    for(int j=0;j<b;j++){
      cin>>tmp;
      g[a-1][tmp-1]=1;
    }
  }
  for(int i=0;i<n;i++) if(c[i]!=1){
      dfs(i);
      t++;
    }

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

  return 0;

}

C++: #include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(obj) (obj).begin(),(obj).end()
typedef long long ll;
ll mod=2e12;
ll cnt=0;
#define max 100005
#define nil -1
int white=0;
int gray=1;
int black=2;
int n,t=0;
int color[101],d[101],f[101],m[101][101];

void DFS(int i){
  color[i]=gray;
  d[i]=++t;
  for(int j=0;j<=n;j++){
    if(m[i][j]==1&&color[j]==white)DFS(j);
  }
  color[i]=black;
  f[i]=++t;
}

int main(){
  int q,w,e;
  cin>>n;
  for(int i=1;i<=n;i++){
    cin>>q>>w;
    for(int j=1;j<=n;j++)m[i][j]=0;
    for(int j=1;j<=w;j++){
      cin>>e;
      m[i][e]=1;
    }
  }

  rep(i,100)color[i]=white;

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

   return 0;
}