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<stdio.h>
#include<stack>

#define MAX 100
#define WHITE 1
#define GRAY 2
#define BLACK 3

using namespace std;

int color[MAX], d[MAX], f[MAX];
int n, A[MAX][MAX];
int tt = 0;

void dfs_visit_1(int u) { //???????????°
    color[u] = GRAY;
    d[u] = ++tt;
    for(int v = 0; v < n; v++) {
        if(A[u][v] == 0) continue;
        if(color[v] == WHITE) dfs_visit_1(v);
    }
    color[u] = BLACK;
    f[u] = ++tt;
}

void dfs_1() { // ???????????°
    for(int i = 0; i < n; i++) {
        color[i] = WHITE;
    }
    tt = 0;
    for(int i = 0; i < n; i++) {
        if(color[i] == WHITE) dfs_visit_1(i);
    }

    for(int i = 0; i < n; i++) {
        printf("%d %d %d\n", i+1, d[i], f[i]);
    }

}

int next(int u) {
    for(int v = 0; v < n; v++) {
        if(A[u][v] == 1) {
            /*
            if(color[v] == WHITE) return v;
            else if(color[v] == BLACK) return -1;
            else if(color[v] == GRAY) continue;
            */
            return v;
        }
    }
    return -1;
}

void dfs_visit_2(int u) {
    color[u] = GRAY;
    d[u] = ++tt;
    stack<int> S;
    S.push(u);

    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;
        }
    }
}


int main()
{
    int u, k, v;
    scanf("%d",&n);

    for(int i = 0; i < n; i++) {
        scanf("%d%d", &u, &k);
        for(int j = 0; j < k; j++) {
            scanf("%d", &v);
            A[u-1][v-1] = 1;
        }
    }


    /*
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < n; j++) {
            printf("%d", A[i][j]);
            if(j != n-1) printf(" ");
        }
        printf("\n");
    }
    */

    for(int i = 0; i < n; i++) {
        color[i] = WHITE;
    }
    dfs_visit_1(0);
    for(int i = 0; i < n; i++) {
        printf("%d %d %d\n", i+1, d[i], f[i]);
    }

    return 0;
}

C++: #include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;
#define rep(i,n) for(ll i=0;i<(n);i++)
#define repr(i,n) for(ll i=(n-1);i>=0;i--)
#define all(x) x.begin(),x.end()
#define br cout << "\n";
using namespace std;
const long long INF = 1e10;
const long long MOD = 1e9+7;
using Graph = vector<vector<ll>>;
using pll = pair<ll, ll>;
template<class T> inline bool chmin(T &a, T b) { if(a > b){ a = b; return true;} return false;}
template<class T> inline bool chmax(T &a, T b) { if(a < b){ a = b; return true;} return false;}

// 0 false, 1 true 
// string to int : -48
// a to A : -32
// ceil(a)  1.2->2.0
// c++17	g++ -std=c++17 a.cpp

ll n;
vector<vector<ll>> to(n);
vector<bool> seen(n);
vector<ll> d(n);
vector<ll> f(n);

ll dfs(ll node, ll time){
    if(seen[node] == false){
        seen[node] = true;
        d[node] = time;
    }

    for(ll next : to[node]){
        if(seen[next]){
            continue;
        }else{
            time = dfs(next, time+1);
        }
    }
    time += 1;

    f[node] = time;

    return time;
}

int main() {
    std::cout << std::fixed << std::setprecision(15);
    cin >> n;
    to.resize(n);
    seen.resize(n);
    d.resize(n);
    f.resize(n);
    rep(i, n){
        ll u; cin >> u; u--;
        ll k; cin >> k;
        rep(j, k){
            ll v; cin >> v; v--;
            to[u].push_back(v);
        }
    }

    ll time = 0;
    for(ll i = 0; i < n; i++){
        if(seen[i] == false){
            time = dfs(i, time+1);
        }
    }
    

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






}

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

enum Color {
	WHITE,
	GRAY,
	BLACK,
};

class dfs {
public:
	dfs(bool matrixT[][100], Color colorT[], int ts_F[], int ts_L[], int verNum) {
		for (int i = 0; i < verNum; i++) {
			for (int j = 0; j < verNum; j++)
				matrixTable[i][j] = matrixT[i][j];
		}
		verNumber = verNum;
	}

	void DFS_Recursive(int nowVerVal) {
		colorTable[nowVerVal] = GRAY;
		++ttl;
		ts_first[nowVerVal] = ttl;

		for (int nextVer = 0; nextVer < verNumber; nextVer++) {
			if (matrixTable[nowVerVal][nextVer] == false) continue;
			if (colorTable[nextVer] != WHITE) continue;
			DFS_Recursive(nextVer);
		}
		colorTable[nowVerVal] = BLACK;
		++ttl;
		ts_last[nowVerVal] = ttl;
	}

	void DFS_InitWithRecursive() {
		ttl = 0;
		for (int i = 0; i < verNumber; i++)
			colorTable[i] = WHITE;

		for (int i = 0; i < verNumber; i++)
			if (colorTable[i] == WHITE) DFS_Recursive(i);
	}

	void DFS_Stack(int firstVerVal) {
		stack<int> stack;
		stack.push(firstVerVal);
		colorTable[firstVerVal] = GRAY;
		++ttl;
		ts_first[firstVerVal] = ttl;

		while (!stack.empty()) {
			int nowVerVal = stack.top();
			int nextVerVal = searchNext(nowVerVal);
			if (nextVerVal != -1) {
				if (colorTable[nextVerVal] == WHITE) {
					colorTable[nextVerVal] = GRAY;
					ts_first[nextVerVal] = ++ttl;
					stack.push(nextVerVal);
				}
			}
			else {
				colorTable[nowVerVal] = BLACK;
				++ttl;
				ts_last[nowVerVal] = ttl;
				stack.pop();
			}
		}
	}

	void DFS_InitWithStack() {
		ttl = 0;
		for (int i = 0; i < verNumber; i++) {
			colorTable[i] = WHITE;
			nextFirstVal[i] = 0;
		}

		for (int i = 0; i < verNumber; i++)
			if (colorTable[i] == WHITE) DFS_Stack(i);
	}

	int searchNext(int nowVerNum) {
		//????????????????????????????????¨????????????????????????
		for (int i = nextFirstVal[nowVerNum]; i < verNumber; i++) {
			nextFirstVal[nowVerNum]++;
			if (matrixTable[nowVerNum][i]) return i;
		}
		return -1;
	}

	void print() {
		for (int i = 0; i < verNumber; i++) {
			cout << i + 1 << " " << ts_first[i] << " " << ts_last[i] << endl;
		}
	}
private:
	bool matrixTable[100][100];
	Color colorTable[100];
	int ts_first[100];
	int ts_last[100];
	int verNumber;
	int ttl;
	int nextFirstVal[100];
};

int main() {
	int verNum; //num??????????????°???value????????????????????????????????¨???
	bool matrixTable[100][100]; //???????????¨??????????????????
	Color colorTable[100];
	int timeStamp_first[100];
	int timeStamp_last[100];
	cin >> verNum;

	for (int i = 0; i < verNum; i++)
		for (int j = 0; j < verNum; j++) {
			matrixTable[i][j] = false;
		}

	for (int i = 0; i < verNum; i++) {
		int verVal, nextVerNum;
		cin >> verVal >> nextVerNum;
		for (int j = 0; j < nextVerNum; j++) {
			int nextVerVal;
			cin >> nextVerVal;
			//0?????????????????´???
			matrixTable[verVal - 1][nextVerVal - 1] = true;
		}
	}

	dfs* d = new dfs(matrixTable, colorTable, timeStamp_first, timeStamp_last, verNum);
	d->DFS_InitWithStack();
	d->print();

	return 0;
}