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 <string>
#include <map>
#include <stack>
#include <algorithm>
using namespace std;
#define MAX 100000

static const int N=100;
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;

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

int next(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 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]=BLACK;
        f[u]=++tt;
    }
  }
}

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

  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
//------------------------------------------
#include <bits/stdc++.h>
//DEFINE
//------------------------------------------
#define ll long long
#define ld long double
#define ALLv(a)  (a).begin(),(a).end()
#define ALL(a,n)  (a),(a)+n
#define vi vector<long long>
#define vd vector<long double>
#define vs vector<string>
#define dcml(n) fixed<<setprecision(n)
//CONST
//------------------------------------------
const ll INF=1010000000000000017LL;
const ll MOD=1000000007LL;
const ld EPS=1e-12;
const ld PI=3.14159265358979323846;
//REPEAT
//------------------------------------------
#define   FOR(i,m,n) for(ll (i)=(m);   (i)<(n);  (i)++)
#define  FORS(i,m,n) for(ll (i)=(m);   (i)<=(n); (i)++)
#define  RFOR(i,m,n) for(ll (i)=(n)-1; (i)>=(n); (i)--)
#define RFORS(i,m,n) for(ll (i)=(n);   (i)>(n);  (i)--)
#define   REP(i,n)   for(ll (i)=0;     (i)<(n);  (i)++)
#define  REPS(i,x)   for(ll (i)=1;     (i)<=(x); (i)++)
#define  RREP(i,x)   for(ll (i)=(x)-1; (i)>=0;   (i)--)
#define RREPS(i,x)   for(ll (i)=(x);   (i)> 0;   (i)--)
#define  WREP(i,in,j,jn) REP(i,in)REP(j,jn)
#define WREPS(i,in,j,jn) REPS(i,in)REPS(j,jn)
//-----------------------------------------
//namespace
using namespace std;
//ライブラリはここに
//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓

//-----------------------------------------
vector<ll> G[110];
bool done[110];
ll START[110],END[110];
ll t=1;
void dfs(ll from){
    done[from]=true;
    if(START[from]==-1) START[from]=t++;
    for(auto r:G[from]){
        if(done[r])continue;
        dfs(r);
    }
    if(END[from]==-1) END[from]=t++;
}
int main(void){
    ll N;cin>>N;
    REP(i,N){
        START[i]=END[i]=-1;
        done[i]=false;
    }
    REP(i,N){
        ll idx;cin>>idx;ll k;cin>>k;
        REP(j,k){
            ll to;cin>>to;to--;
            G[i].push_back(to);
        }
    }
    REP(i,N) dfs(i);
    REP(i,N){
        printf("%lld %lld %lld\n",i+1,START[i],END[i]);
    }
}

C++: #include<bits/stdc++.h>
using namespace std;

typedef long long ll;

vector<vector<ll>> graph(100);
vector<bool> visit(100,false);
vector<ll> d(100);
vector<ll> f(100);
ll tmp = 0;

void dfs(ll v)
{
    ll i;
    visit.at(v) = true;
    d.at(v) = ++tmp;
    for(i = 0;i < graph.at(v).size();++i){
        ll g = graph.at(v).at(i);
        if(visit.at(g)){
            continue;
        }
        dfs(g);
    }
    f.at(v) = ++tmp;
    return;
}

int main()
{
    ll i,j;
    ll n;
    cin >> n;
    for(i = 0;i < n;++i){
        ll u,k;
        cin >> u >> k;
        for(j = 0;j < k;++j){
            ll v;
            cin >> v;
            graph.at(u-1).push_back(v-1);
        }
    }
    for(i = 0;i < n;++i){
        if(!visit.at(i)){
            dfs(i);
        }
    }
    for(i = 0;i < n;++i){
        cout << i+1 << " " << d.at(i) << " " << f.at(i) << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<stack>
#include<vector>
#include<string>
#include<algorithm>

struct node {
	int num;
	std::vector<int> child;
};

int recurcive(node nodes[],int d[100], int f[100], int n, int count) {
	d[n] = count++;
	for (size_t i = 0; i < nodes[n].child.size(); i++) {
		if (d[nodes[n].child[i]] == 0) {
			count = recurcive(nodes, d, f, nodes[n].child[i], count);
		} else {
			nodes[n].child.erase(std::find(nodes[n].child.begin(), nodes[n].child.end(), nodes[n].child[i]));
			i--;
		}
	}
	f[n] = count++;

	return count;
}

int main() {
	int node_num;
	node nodes[100];
	std::cin >> node_num;

	for (int i = 0; i < node_num; i++) {
		int n, num;
		std::cin >> n >> num;
		for (int j = 0; j < num; j++) {
			int val;
			std::cin >> val;
			nodes[n - 1].child.push_back(val - 1);
		}
	}

	std::stack<int> st, st2;
	std::vector<int> gone;
	int d[100], f[100];
	int count = 1;

	for (int i = 0; i < 100; i++)
		d[i] = f[i] = 0;

	for (int i = 0; i < node_num; i++) {
		if (d[i] == 0) {
			count = recurcive(nodes, d, f, i, count);
		}
	}

	for (int i = 0; i < node_num; i++) {
		std::cout << i + 1 << " " << d[i] << " " << f[i] << std::endl;
	}
	
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

int times;
vector<vector<int> > lists;
vector<int> stampA;
vector<int> stampB;

void dfs(int point){
    times++;
    stampA.at(point-1)=times;
    for(int i=0;i<(int)lists.at(point-1).size();i++){
        if(stampA.at(lists.at(point-1).at(i)-1)==0) dfs(lists.at(point-1).at(i));
    }
    times++;
    stampB.at(point-1)=times;
    
}

int main(){
    times=0;
    int n;
    cin >> n;
    lists.resize(n,vector<int>());
    stampA.resize(n,0);
    stampB.resize(n,0);
    for(int i=0;i<n;i++){
        int u,k;
        cin >> u >> k;
        for(int j=0;j<k;j++){
            int v;
            cin >> v;
            lists.at(u-1).push_back(v);
        }
    }
    
    for(int i=0;i<n;i++){
        if(stampA.at(i)==0) dfs(i+1);
    }
    
    for(int i=0;i<n;i++){
        cout << i+1 << " " << stampA.at(i) << " " << stampB.at(i) << endl;
    }
}

C++: #include <bits/stdc++.h>
#define r(i,a,n) for(int i=a;i<n;i++)
using namespace std;
int a[101][101],start[101],end[101],n,p=0,v[101];
void dfs(int u){
    if(!v[u]){v[u]++;
    start[u]=++p;
    r(i,1,n+1)if(a[u][i])dfs(i);
    end[u]=++p;}
}
int main(){
    int q,qq,qqq;
    cin>>n;
    r(i,0,n){cin>>q>>qq;
        r(i,0,qq){cin>>qqq;
            a[q][qqq]++;
        }
    }
    r(i,1,n+1)if(!v[i])dfs(i);
    r(i,1,n+1)cout<<i<<' '<<start[i]<<' '<<end[i]<<endl;
}