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<bits/stdc++.h>
using namespace std;
using ll=long long;
#define fi first
#define se second
using Graph=vector<vector<int>>;

void dfs(int s,Graph graph,vector<int> &d,vector<int> &f,int &flag1,int &flag2)
{
	int n=graph.size();
	d[s]=flag1;
	flag1++;
	for (int i=0;i<n;i++)
	{
		if (graph[s][i]==1 && d[i]==-1) dfs(i,graph,d,f,flag1,flag2);
	}
	f[s]=flag2;
	flag2++;
}
int main()
{
	int n;cin >> n;
	Graph graph(n,vector<int> (n,0));
	int u,k,v;
	for (int i=0;i<n;i++)
	{
		cin >>u;
		cin >>k;
		for (int j=0;j<k;j++)
		{
			cin >>v;
			graph[u-1][v-1]=1;
		}
	}
	int flag1=1,flag2=1;
	vector<int> d(n,-1),f(n-1);
	for (int i=0;i<n;i++)
	{
		if (d[i]==-1) dfs(i,graph,d,f,flag1,flag1);
	}
	
	for (int i=0;i<n;i++)
	{
		cout <<i+1 <<" " << d[i] <<" " << f[i] << endl;
	}
	return 0;
}

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

using namespace std;

int n, u, k, v, d[110], f[110], tim=0;
bool vis[110];
vector<int> adj[110];

void dfs (int p)
{
    tim++;
    vis[p]=true;
    d[p]=tim;
    for (auto u : adj[p])
    {
        if (!vis[u]) dfs(u);
    }
    tim++;
    f[p]=tim;
}

int main()
{
    memset(vis, false, sizeof(vis));
    cin>>n;
    for (int i=0; i<n; i++)
    {
        cin>>u>>k;
        for (int j=0; j<k; j++)
        {
            cin>>v;
            adj[u].push_back(v);
        }
    }
    for (int i=1; i<=n; i++)
    {
        if (!vis[i]) dfs(i);
    }
    for (int i=1; i<=n; i++)
    {
        cout<<i<<' '<<d[i]<<' '<<f[i]<<'\n';
    }
    return 0;
}

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

using namespace std;
int n,u,k;

class points{
    public:
    int flag=0;
    list<int> l;
    int d=0;
    int f=0;
}pt[110];
int tem;

int times=0;

void dfa(int cur){
    times+=1;
    pt[cur].d=times;
    pt[cur].flag=1;
    while(!pt[cur].l.empty()){
        int dst=pt[cur].l.front();
            if(pt[dst].flag==0){
                dfa(dst);
            }
        pt[cur].l.pop_front();
    }
    times+=1;
    pt[cur].f=times;
}

int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>u>>k;
        for(int j=0;j<k;j++){
            cin>>tem;
            pt[u].l.push_back(tem);
        }
    }
    for(int i=1;i<=n;i++){
        if(pt[i].flag==0){
            dfa(i);
        }
    }
    for(int i=1;i<=n;i++){
        cout<<i<<" "<<pt[i].d<<" "<<pt[i].f<<endl;
    }
    
}

C++: #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 BLACK = 2;

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

int next(int M[N][N], int n, 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 M[N][N], int n, 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(M, n, 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 M[N][N], int n) {
    for (int i = 0; i < n; ++i) {
        color[i] = WHITE;
        nt[i] = 0;
    }
    tt = 0;

    for (int i = 0; i < n; ++i) {
        if (color[i] == WHITE) dfs_visit(M, n, i);
    }
    for (int i = 0; i < n; ++i) {
        cout << i + 1 << " " << d[i] << " " << f[i] << endl;
    }
}

int main() {

    int n;
    cin >> n;

    int M[N][N] = {0};
    int u, k, v;
    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(M, n);

    return 0;
}

C++: #include<stdio.h>

#define WHITE 0   // not visited yet.
#define GRAY 1    // visited, but not completed.
#define BLACK 2   // search completed.

int G[101][101];        // adjacency list.
int color[101];         // visited/completed sign.
int n;                  // size.
int d[101], f[101], t;  // first visit time/complete time.

void search_loop(int i) 
{
    int next;
    d[i] = ++t;
    color[i] = GRAY;  // first visited.

    for(next = 1; next <= n; next++){
        if(i == next && G[i][i] > 0) break;   // if self-looped, through.
        if(G[i][next] > 0 && color[next] == WHITE){  // if not visited yet, visit.
            search_loop(next);
        }
    }
    f[i] = ++t;
    color[i] = BLACK;  // completed. 

    return;
}

void dfs()
{
    int i;
    for(i = 1; i <= n; i++) color[i] = WHITE;  // initialize.
    t = 0;

    for(i = 1; i <= n; i++) if(color[i] == WHITE) search_loop(i);

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

    return ;
}

int main()
{
    int i, j, k, e;
    scanf("%d", &n);
    for(i = 1; i <= n; i++){
        for(j = 1; j <= n; j++){ G[i][j] = 0; } }

    do{
        scanf("%d %d", &i, &e);
        for(j = 1; j <= e; j++){
            scanf("%d", &k);
            G[i][k] = 1;
        }
    }while(i < n);

    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;
    }
  }
  dfs(0);

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

  return 0;

}