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 <vector>
#include <stack>
#include <utility>
using namespace std;
int _time = 0;
stack<int> route;
void dfs(int root, vector<vector<bool>> &conn_mat, vector<bool> &accessed, vector<pair<int, int>> &result)
{
	accessed[root] = true;
	result[root].first = _time;
	int index;
	bool end = true;
	for (index = 0; index < conn_mat.size(); index++)
	{
		if (conn_mat[root][index] == true && accessed[index] == false)
		{
			_time++;
			result[index].first = _time;
			dfs(index, conn_mat, accessed, result);
			end = false;
		}
	}
	if (end)
	{
		_time++;
		result[root].second = _time;
		return;
	}
	_time++;
	result[root].second = _time;
	return;
}

int main()
{

	int n_node, index, n_cn, cn;
	cin >> n_node;
	vector<bool> vertex(n_node, false);
	vector<vector<bool>> conn_mat(n_node, vertex);
	vector<bool> &accessed = vertex;
	vector<pair<int, int>> result(n_node, make_pair(1, 0));
	while (n_node--)
	{
		cin >> index >> n_cn;
		while (n_cn--)
		{
			cin >> cn;
			conn_mat[index - 1][cn - 1] = true;
		}
	}
	bool end = false;
	while (!end) {
		_time++;
		int i = 0;
		while (accessed[i]) {
			i++;
		}
		dfs(i, conn_mat, accessed, result);
		end = true;
		for (auto acc : accessed) {
			end = end && acc;
		}
	}
	int i = 1;
	for (auto out : result) {
		cout << i << ' ' << out.first << ' ' << out.second << endl;
		i++;
	}
	return 0;
}

C++: /**
 * Depth first search.
 * start from node 1
 * 1) increment time 
 * 2) find non visited adjacent node
 * 3) if found move to that node.  d[v'] = time
 * 4) if not found. f[v] = time
 * 5) else end.
 * 5) go to 2.
 */

#include <iostream>
using namespace std;
const int N = 101;
int adj[N][N] = {0};
int d[N]={0};
int f[N]={0};
int t = 1;

void dfs(int n) {
	if (d[n]) return;
	d[n]=++t;
	int k = adj[n][0];
	for (int j=1;j<=k;j++) {
		dfs(adj[n][j]);
	}
	f[n]=++t;
}

int main()
{
	int n;
	cin >> n;
	for (int i=1;i<=n;i++){
		int j, k;
		cin >> j >> k;
		adj[j][0]=k;
		for (int m=1;m<=k;m++) {
			int a;
			cin >> a;
			adj[j][m]=a;
		}
	}

	for (int i=1;i<=n;i++){
		dfs(i);
	}

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

	return 0;
}

C++: #include <cstdio>
#include <vector>
using namespace std;

void dfs(int cur, vector<vector<int> > arr, int d[], int f[], int &time, int n, bool psd[]){
    d[cur] = time;
    time++;
    psd[cur] = true;
    for(int dst = 0; dst < n; dst++){
        if(arr[cur][dst] == 1 && !psd[dst]){
            dfs(dst,arr,d,f,time,n,psd);
        }
    }
    f[cur] = time;
    time++;
}

int main(){
    int n;
    scanf("%d",&n);
    vector<vector<int> > arr(n,vector<int>(n));
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            arr[i][j] = 0;
        }
    }
    for(int i = 0; i < n; i++){
        int u,k;
        scanf("%d %d",&u,&k);
        for(int j = 0; j < k; j++){
            int v;
            scanf("%d",&v);
            arr[u-1][v-1] = 1;
        }
    }
    int d[n],f[n],time = 1;
    bool psd[n];
    for(int i = 0; i < n; i++){
        psd[i] = false;
    }
    for(int cur = 0; cur < n; cur++){
        if(!psd[cur]){
            dfs(cur,arr,d,f,time,n,psd);
        }
    }
    for(int id = 0; id < n; id++){
        printf("%d %d %d\n", id+1, d[id], f[id]);
    }
}

C++: #include <stdio.h>
#include <iostream>
using namespace std;

class Adjl{
private:
	int u;
	int k;
	Adjl **next;
protected:
	int d;
	int f;
public:
	Adjl(int u);
	~Adjl(){ if (next != NULL) delete[] next; }
	void setV(int k, Adjl *vk);
	int depthFirstSearch(int time);
	void print();
};

Adjl::Adjl(int u)
{
	this->u = u;
	k = 0;
	next = NULL;
	d = 0;
	f = 0;
}

void Adjl::setV(int k, Adjl *vk)
{
	if (this->k == 0) next = new Adjl*[k];
	next[this->k] = vk;
	(this->k)++;
}

int Adjl::depthFirstSearch(int time)
{
	time++;
	d = time;
	for (int i = 0; i < k; i++) {
		if (next[i]->d == 0) {
			time = next[i]->depthFirstSearch(time);
		}
	}
	time++;
	f = time;
	return time;
}

void Adjl::print()
{
	cout << u << " " << d << " " << f << endl;
}

int main(void)
{
	int n;
	cin >> n;
	
	Adjl **adjl = new Adjl*[n];
	int check[100] = {0};

	for (int i = 0; i < n; i++) {
		int u, k;
		cin >> u >> k;
		if (check[i] == 0) {
			adjl[i] = new Adjl(u);
			check[i] = 1;
		}
		check[i] = 1;
		for (int j = 0; j < k; j++) {
			int vk;
			cin >> vk;
			if (check[vk - 1] == 0) {
				adjl[vk - 1] = new Adjl(vk);
				check[vk - 1] = 1;
			}
			adjl[i]->setV(k, adjl[vk - 1]);
		}
	}

	adjl[0]->depthFirstSearch(0);

	for (int i = 0; i < n; i++) {
		adjl[i]->print();
	}

	delete[] adjl;
	return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i,n) for(int i=0; i<(n); i++)
#define FOR(i,a,n) for(int i=(a); i<(n); i++)
#define all(v) v.begin(), v.end()
using namespace std;
typedef long long ll;
const int INF = 1e9;
const int MOD = 1e9+7;

using Graph = vector<vector<int>>;
Graph G;

vector<int> d, f;

int dfs(int v, int t) {
    if(d[v]==0) d[v]=t;
    int res = t;
    for(const auto nv: G[v]) {
        if (d[nv]) continue;
        res = dfs(nv, res+1);
    }
    return f[v] = ++res;
}

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

    int n; cin >> n;
    G.resize(n);
    rep(i, n) {
        int x, k; cin >> x >> k;
        x--;
        rep(j, k) {
            int v; cin >> v; v--;
            G[x].push_back(v);
        }
    }

    d.assign(n, 0); f.assign(n, 0);

    int cur = 1;
    rep(i, n) {
        if (!d[i]) {
            cur = dfs(i, cur);
            cur++;
        }
    }
    rep(i, n) {
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
}

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

using ll = long long;
using namespace std;

/* initialize */
int color[100], nt[100], d[100], f[100], tt;
int A[100][100];
int n;

int next(int u){
    for (int v = nt[u]; v < n; ++v) {
        nt[u] = v + 1;
        if( A[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] = 1;
    d[r] += ++tt;

    while (!S.empty()){
        int u = S.top();
        int v = next(u);
        if (v != -1){
            if (color[v] == 0){
                color[v] = 1;
                d[v] = ++tt;
                S.push(v);
            }
        } else{
            S.pop();
            color[u] = 2;
            f[u] = ++tt;
        }
    }
}
void dfs(){
    for (int i = 0; i < n; ++i) {
        color[i] = 0;
    }
    tt = 0;

    for (int u = 0; u < n; ++u) {
        if (color[u] == 0) dfs_visit(u);
    }
    for (int i = 0; i < n; ++i) {
        cout << i+1 << " " << d[i] << " " << f[i] << "\n";
    }
}
/* main */
int main() {
    int u, k, v;
    cin >> n;
    for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j) A[i][j] = 0;
    for (int i = 0; i < n; ++i) {
        cin >> u >> k;
        for (int j = 0; j < k; ++j) {
            cin >> v;
            A[u-1][v-1] = 1;
        }
    }

    dfs();
    return 0;
}