Go: #include <bits/stdc++.h>
using namespace std;
static const int WHITE = 0;
static const int GRAY  = 1;
static const int BLACK = 2;
static const int N     = 100;

int n, tt;
vector<vector<int>> M(N, vector<int>(N));
vector<int> color(N), d(N), f(N);

void dfs_visit(int u) {
  color[u] = GRAY;
  d[u]     = ++tt;
  for (int v = 0; v < n; v++) {
    if (M[u][v] == 0) continue;
    if (color[v] == WHITE) { dfs_visit(v); }
  }
  color[u] = BLACK;
  f[u]     = ++tt;
}

void dfs() {
  tt = 0;

  for (int u = 0; u < n; u++) {
    if (color[u] == WHITE) dfs_visit(u);
  }
  for (int u = 0; u < n; u++) {
    printf("%d %d %d\n", u + 1, d[u], f[u]);
  }
}

int main() {
  int u, v, k;
  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();
}

C++: #include <iostream>
#include <iomanip> // << fixed << setprecision(xxx)
#include <algorithm> // do { } while ( next_permutation(A, A+xxx) ) ;
#include <vector>
#include <string> // to_string(nnn) // substr(m, n) // stoi(nnn)
#include <complex>
#include <tuple> // get<n>(xxx)
#include <queue>
#include <stack>
#include <map> // if (M.find(key) != M.end()) { }
#include <set> // S.insert(M);
// if (S.find(key) != S.end()) { }
// for (auto it=S.begin(); it != S.end(); it++) { }
// auto it = S.lower_bound(M);
#include <random> // random_device rd; mt19937 mt(rd());
#include <cctype>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib> // atoi(xxx)
using namespace std;

#define DEBUG 0 // change 0 -> 1 if we need debug.
// insert #if<tab> by my emacs. #if DEBUG == 1 ... #end

typedef long long ll;

// const int dx[4] = {1, 0, -1, 0};
// const int dy[4] = {0, 1, 0, -1};

// const int C = 1e6+10;
// const ll M = 1000000007;

class Edge {
public:
  int src, dst, cost;
  Edge(int s, int d, int c)
    : src(s), dst(d), cost(c) {}
  friend bool operator<(const Edge& x, const Edge& y) {
    return x.cost < y.cost;
  }
};

typedef Edge State;

class Graph {
public:
  int N;
  vector<Edge>* V;
  int* visited;
  int* from;
  int time;
  int* time_d;
  int* time_f;

  Graph(int n)
    : N(n), time(0) {
    V = new vector<Edge>[N];
    from = new int[N];
    time_d = new int[N];
    time_f = new int[N];
    visited = new int[N];
  }
  ~Graph() {
    delete[] V;
    delete[] from;
    delete[] time_d;
    delete[] time_f;
    delete[] visited;
  }

  void add_edge(int src, int dst, int cost = 1) {
    V[src].push_back(Edge(src, dst, cost));
  }

  void dfs(int start) {
    fill(visited, visited+N, 0);
    stack<State> S;
    S.push(State(-1, start, 0));
    while (!S.empty()) {
      State s = S.top();
      S.pop();
      if (visited[s.dst] == 0) {
        visited[s.dst] = 1;
        time_d[s.dst] = time++;
        from[s.dst] = s.src;
        S.push(s);
        for (auto x : V[s.dst]) {
          if (visited[x.dst] == 0) {
            S.push(State(s.dst, x.dst, s.cost + x.cost));
          }
        }
      } else if (visited[s.dst] == 1) {
        visited[s.dst] = 2;
        time_f[s.dst] = time++;
      }
    }
  }
};

int main () {
  int n;
  cin >> n;
  Graph graph(n);
  for (auto i = 0; i < graph.N; ++i) {
    int u, k;
    cin >> u >> k;
    --u;
    for (auto j = 0; j < k; ++j) {
      int v;
      cin >> v;
      --v;
      graph.add_edge(u, v);
    }
  }
  for (auto i = 0; i < graph.N; ++i) {
    sort(graph.V[i].begin(), graph.V[i].end());
    reverse(graph.V[i].begin(), graph.V[i].end());
  }
  while (true) {
    bool used = false;
    for (auto i = 0; i < graph.N; ++i) {
      if (graph.visited[i] == 0) {
        graph.dfs(i);
        used = true;
        break;
      }
    }
    if (!used) break;
  }
  for (auto i = 0; i < graph.N; ++i) {
    cout << i+1
         << " " << graph.time_d[i]+1
         << " " << graph.time_f[i]+1 << endl;
  }
}

C++: #include <bits/stdc++.h>
using namespace std;
bool A[105][105],vist[105]={0};
int d[105],f[105],n,t=0;

void dfs(int v){
	d[v] = ++t;
	vist[v] = 1;
	for(int i=1;i<=n;i++)
		if(A[v][i] && !vist[i])		
			dfs(i);
	f[v] = ++t;  
}
int main()
{	
	memset(A,0,sizeof(A));
	int v,u,du;
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>v>>du;
		while(du--)
			cin>>u,
			A[v][u] = 1;
	}
	for(int i=1;i<=n;i++)
		if(!vist[i]) dfs(i);
	for(int i=1;i<=n;i++)
		printf("%d %d %d\n",i,d[i],f[i]);
	return 0;
}

C++: #include<stdio.h>
#include<stdlib.h>
 
#define WHITE 10000
#define BLACK 10001
#define GRAY 10002
#define TRUE 1
#define FALSE 0
#define NUL NULL
 
void dfs(void);
void visit(int);
void push(int);
void pop(void);
int isEmpty(void);
 
int v[101][101],s[101],time1,n;
int *d,*f,*color;
int top = 0;
 
int main(){
  int u,i,j,w,k;
 
  scanf("%d",&n);
 
  d = malloc(sizeof(int) * (n + 1));
  f = malloc(sizeof(int) * (n + 1));
  color = malloc(sizeof(int) * (n + 1));
 
  for(i = 1;i <= n;i++){
    scanf("%d %d",&u,&k);
    for(j = 1;j <= k;j++){
      scanf("%d",&w);
      v[i][w] = 1;
    }
  }
 
  dfs();
 
  for(i = 1;i <= n;i++){
    printf("%d %d %d\n",i,d[i],f[i]);
  }
 
  return 0;
}
 
void dfs(){
  int i = 1,j = 1;
  for(i = 1;i <= n;i++){
      color[i] = WHITE;
  }
 
  time1 = 0;
 
  for(i = 1;i <= n;i++){
    if(color[i] == WHITE){
      visit(i);
    }
  }    
 
}
 
void visit(int r){
  int u,vv=NUL,i;
 
  push(r);
  color[r] = GRAY;
  d[r] = ++time1;
 
  while(isEmpty() == FALSE){
    vv=NUL;
    u = s[top];
    for(i = 1;i <= n;i++){
    if(v[u][i] == 1 && color[i] == WHITE){
      vv = i;
      break;
    }
     
    }
    if(vv != NUL){
      if(color[vv] == WHITE){
    push(vv);
    color[vv] = GRAY;
    d[vv] = ++time1;
      }
    }
    else{
      pop();
      color[u] = BLACK;
      f[u] = ++time1;
    }
  }
}
 
void push(int x){
  top++;
  s[top] = x;
}
 
int isEmpty(){
  if(top == 0){
    return TRUE;
  }
  else{
    return FALSE;
  }
}
 
void pop(){
  top--;
}

C++: #include <stdio.h>
#define N 100
#define W 0
#define X 1
#define Z 2

int n,m[N][N];
int c[N],d[N],f[N],tt;

void dfs_visit(int u){
  int i;
  c[u] = X;
  ++tt;
  d[u] = tt;
  for(i=0;i<n;i++){
    if(m[u][i] == 0) continue;
    else if(c[i]==W){
      dfs_visit(i);
    }
  }
  c[u]=Z;
  ++tt;
  f[u]=tt;
}

void dfs(){
  int i;
  for(i=0;i<n;i++){
    c[i] = W;
  }
  tt = 0;

  for(i=0;i<n;i++){
    if(c[i]==W)dfs_visit(i);
  }
  for(i = 0 ;i<n;i++){
    printf("%d %d %d\n", i+ 1,d[i],f[i]);
  }
}

int main(){
  int u,v,k,i,j;

  scanf("%d",&n);
  for(i = 0;i<n;i++){
    for(j=0;j<n;j++)m[i][j]=0;
  }

  for(i=0;i<n;i++){
    scanf("%d %d",&u,&k);
    u--;
    for(j=0;j<k;j++){
      scanf("%d",&v);
      v--;
      m[u][v]=1;
    }
  }
  dfs();

  return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <cstdio>
#include <stack>
using namespace std;
stack<int> st;
int  v[102][101], n;
int  time[102][2];
int ct = 1;
inline void search(int t) {
	if(!time[t][0]) time[t][0] = ct++;
	int tf = 0;
	for (int a = 1; a <= n; a++) {
		if (v[t][a]) {
			st.push(a);
			for (int i = 1; i <= n; i++) {
				v[i][a] = 0;
			}
			search(st.top());
			tf = 1;
		}
	}
		
	if(!tf) {
		st.pop();
		time[t][1] = ct++;
		if(!st.empty()) search(st.top());
	}
}
int main() {
	for (int i = 1; i <= n; i++) {
		time[i][0] = 0;
	}
	st.push(1);
	int u, k, s;
	cin >> n;
	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++) {
		cin >> u;
		cin >> k;
		for (int j = 0; j < k; j++) {
			cin >> s;
			v[u][s] = 1;
		}
	}
	search(1);
	for (int i = 1; i <= n; i++) {
		cout << i << " " << time[i][0] << " " << time[i][1] << endl;
	}
	return 0;
}