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;

#define N_MAX 100
#define WH 0
#define GR 1
#define BK 2

long n;
long ttime = 0;
long G[N_MAX][N_MAX] = {};
long D[N_MAX], F[N_MAX];
long color[N_MAX] = {};

void dfs_rec(long u) {
    color[u] = GR;
    ttime++;
    D[u] = ttime;
    // cout << "start time " << u << ": " << D[u] << endl;

    for (long v = 0; v < n; v++) {
        // cout << "(u, v) = (" << u << ", " << v << ")" << endl;
        if (G[u][v] == 1 && color[v] == WH) {
            dfs_rec(v);
        }
    }
    color[u] = BK;
    ttime++;
    F[u] = ttime;
    // cout << "end time " << u << ": " << F[u] << endl;
}

int main() {
    long v_from, deg_out, v_to;

    cin >> n;
    for (long i = 0; i < n; i++) {
        cin >> v_from >> deg_out;
        v_from--;
        for (long j = 0; j < deg_out; j++) {
            cin >> v_to;
            v_to--;
            G[v_from][v_to] = 1;
        }
    }

    // for (long i = 0; i < n; i++) {
    //     for (long j = 0; j < n; j++) {
    //         if (j != 0) { cout << " "; }
    //         cout << G[i][j];
    //     }
    //     cout << endl;
    // }

    for (long u = 0; u < n; u++) {
        if (color[u] == WH) {
            dfs_rec(u);
        }
    }

    for (long i = 0; i < n; i++) {
        cout << i + 1 << " " << D[i] << " " << F[i] << endl;
    }

    return 0;
}

C++: #include<iostream>
#include<stack>
using namespace std;

struct time_check {
    int find_time, end_time;
};

int G[101][101] = {0};
time_check t[101];
int elapsed = 1, n;
stack<int> S;

void dfs(int start) {
    S.push(start);
    while (! S.empty()) {
        elapsed++;
        int u = S.top();
        for (int i = 1; i <= n + 1; i++) {
            if (G[u][i] == 1 && t[i].end_time == 0) {
                t[i].find_time = elapsed;
                G[u][i] = 0;
                S.push(i);
                break;
            }
            if (i == n + 1) {
                t[u].end_time = elapsed;
                S.pop();
            }
        }
    }
}

int main() {
    for (int i = 1; i <= 100; i++) t[i].end_time = 0;

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

    t[1].find_time = 1;

    for (int i = 1; i <= n; i++) {
        if (t[i].end_time == 0) dfs(i);
    }

    for (int i = 1; i <= n; i++) {
        cout << i << " " << t[i].find_time << " " << t[i].end_time << endl;
    }

    return 0;
}

/*
#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 BRACK = 2;

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

// uに隣接するvを番号順に取得
int next(int u) {
    for (int v = nt[u]; v < n; v++) {
        nt[u] = v + 1;
        if (M[u][v]) return v;
    }
    return -1;
}

// スタックを用いた深さ優先探索
void dfs_visit(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(u);
        if (v != -1) {
            if (color[v] == WHITE) {
                color[v] = GRAY;
                d[v] = ++tt;
                S.push(v);
            }
        } else {
            S.pop();
            color[u] = BRACK;
            f[u] = ++tt;
        }
    }
}

void dfs() {
    // 初期化
    for (int i = 0; i < n; i++) {
        color[i] = WHITE;
        nt[i] = 0;
    }
    tt = 0;

    // 未訪問のuを始点として深さ優先探索
    for (int u = 0; u < n; u++) {
        if (color[u] == WHITE) dfs_visit(u);
    }
    for (int i = 0; i < n; i++) {
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
}

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

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

    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>
#include "string.h"
#include "stdio.h"
using namespace std;
int n,m[107][107];
int color[107],d[107],f[107],tt;

void dfs_visit(int u)
{
	int v;
	color[u]=1;
	d[u]=++tt;
	for(v=0;v<n;v++)
	{
		if(m[u][v]==0)continue;
		if(color[v]==0)dfs_visit(v);
	}
	color[u]=2;
	f[u]=++tt;
}

void dfs()
{
	int u;
	for(u=0;u<n;u++)color[u]=0;
	tt=0;
	
	for(u=0;u<n;u++)
		if(color[u]==0)dfs_visit(u);
	for(u=0;u<n;u++)
		printf("%d %d %d\n",u+1,d[u],f[u]);
}
int main(int argc, char *argv[]) {
	int u,k,v,i,j;
	cin>>n;
	memset(m, 0, sizeof(m));
	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++: #include <iostream>
using namespace std;

int n, t = 0;
int v[100][100];
int d[100], f[100], r[101];

void st(int id) {
	if (!r[id]) {
		r[id]++;
		d[id - 1] = ++t;
		for (int i = 0; i < n; i++)
			if (v[id - 1][i])
				st(i + 1);
		f[id - 1] = ++t;
	}
}

int main()
{
	cin >> n;

	for (int i = 0; i < n; i++) {
		int u, k, s;

		cin >> u >> k;

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

	st(1);

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

	return 0;
}

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

using namespace std;

void dfs(const vector<vector<int> > &G, vector<vector<int> > &visitTime, int& count, int node)
{
  if(visitTime[node][0] != 0){
    return;
  }else{
    visitTime[node][0] = ++count;
  }
  for (int i = 0; i < G.size();i++){
    if(G[node][i] == 1){
      dfs(G, visitTime, count, i);
    }
  }
  visitTime[node][1] = ++count;
}

int main()
{
  int N, U, K, V;
  int count = 0;
  cin >> N;
  vector<vector<int> > G(N, vector<int>(N, 0));
  vector<vector<int> > visitTime(N, vector<int>(2, 0));
  for (int i = 0; i < N; i++)
  {
    cin >> U >> K;
    for (int j = 0; j < K;j++){
      cin >> V;
      G[U - 1][V - 1] = 1;
    }
  }
  for (int i = 0; i < N;i++){
    dfs(G, visitTime, count, i);
  }
  for (int i = 0; i < N;i++){
    cout << i + 1 << " " << visitTime[i][0] << " " << visitTime[i][1] << endl;
  }
  return 0;
}