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<stack>
using namespace std;

struct time_check {
    int find_time, end_time;
};

int G[101][101] = {0};
time_check t[101];
int elapsed = 0, 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].find_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].find_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;
        }
    }

    for (int i = 1; i <= n; i++) {
        if (t[i].end_time == 0) {
            t[i].find_time = ++elapsed;
            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 <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)

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

void dfs_visit(int i) {
    color[i] = gray;
    d[i] = ++tt;
    REP(v, n) {
        if (M[i][v] == 0) continue;
        if (color[v] == white) {
            dfs_visit(v);
        }
    }
    color[i] = black;
    f[i] = ++tt;
}

void dfs() {
    REP(i, n) color[i] = white;
    tt = 0;

    REP(i, n) {
        if (color[i] == white) dfs_visit(i);
    }
    REP(i, n) {
        cout << i + 1 << " " << d[i] << " " << f[i] << endl;
    }
}

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

    cin >> n;
    REP(i, n) REP(j, n) M[i][j] = 0;

    REP(i, n) {
        cin >> u >> k;
        u--;
        REP(j, k) {
            cin >> v;
            v--;
            M[u][v] = 1;
        }
    }

    dfs();
    return 0;
}

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

typedef vector<vector<ll>> graph;

ll dfs(graph &G, vector<ll>&d, vector<ll>&f, ll node, ll count){

    if(d[node] != -1) return count;

    d[node] = count;
    count ++;

    for(ll tar : G[node]){
        if( d[tar] == -1 ){
            count = dfs(G, d, f, tar, count);
        }
    }

    f[node] = count;
    count ++;

    return count;

}


int main(){

    ll N;
    cin >> N;

    graph G(N);
    for (int i = 0; i < N; i++)
    {
        ll u,k;
        cin >> u >> k;
        for (int j = 0; j < k; j++)
        {
            ll v;
            cin >> v;
            G[u-1].push_back(v-1);
        }
    }

    vector<ll> d(N,-1),f(N,-1);

    ll count = 1;
    for (ll i = 0; i < N; i++)
    {
       count = dfs(G,d,f,i,count);
    }

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

C++: #include <cstdio>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;

bool A[110][110];
int flag[110],in[110],out[110];
int now=1,n;

void dfs(int u){
	flag[u]=1;
	in[u]=now++;
	for(int i=1;i<=n;i++){
		if(flag[i]==0 && A[u][i]==true){
			dfs(i);
		}
	}
	out[u]=now++;
	return ;
}

int main(){
	int a,b,c;
	cin>>n;
	for(int i=1;i<=n;i++){
			for(int j=1;j<=n;j++){
				A[i][j]=false;
		}
	}
	for(int i=1;i<=n;i++){
		cin>>a>>b;
		for(int j=1;j<=b;j++){
			cin>>c;
			A[a][c]=true;
		}
	}
	for(int i=1;i<=n;i++){
		if(flag[i]==0) dfs(i);
	}
	for(int i=1;i<=n;i++){
		cout<<i<<" "<<in[i]<<" "<<out[i]<<endl;
	}
	return 0;
}

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

int next(int u){
	for(int v = nt[u]; v < n; v++) {
		nt[u] = v + 1;
		if(M[u][v] = 1) 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 {
		   color[u] = BLACK;
		   S.pop();
		   f[u] = ++tt;
		}
	} 
}


void dfs() {
	for(int i = 0; i < n; i++) {
	     color[i] = WHITE;
	}	
	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 n, k , u, v;
	tt = 0;
	cin >> n;
	for(int i = 0; i < n; i++) {
		for(int j = 0; j < n; j++) {
			M[i][j] = 0;
		}
	}
	cin >> k >> u;
	u--;
	for(int i = 0; i < k; i++) {
	    cin >> v;
	    v--;
		M[u][v] = 1; 
	}
	dfs();
	return 0;
}