Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

// repr state of visited node
// WHITE yet visit
// GEAY  visiting
// BLACK visited
const (
	WHITE int = iota
	GRAY
	BLACK
)

type dfsGraph struct {
	g      [][]int
	colors []int
	stime  []int // Start time of visiting node
	ftime  []int // Finish time of visiting node
}

var time int

func makeAdjList() [][]int {
	var n int
	fmt.Scanf("%d", &n)

	adj := make([][]int, n)
	for i := 0; i < n; i++ {
		adj[i] = make([]int, n)
	}

	sc := bufio.NewScanner(os.Stdin)
	for i := 0; i < n; i++ {
		sc.Scan()
		nodeInfo := strings.Split(sc.Text(), " ")
		outDegree, _ := strconv.Atoi(nodeInfo[1])

		if outDegree > 0 {
			for k := 0; k < outDegree; k++ {
				j, _ := strconv.Atoi(nodeInfo[k+2])
				j-- // convert 1 based to 0 based
				adj[i][j] = 1
			}
		}
	}

	return adj
}

func (dg dfsGraph) dfsVisit(u int) {
	// 頂点uを訪問中に設定
	dg.colors[u] = GRAY
	time++
	dg.stime[u] = time

	// uの隣接nodeを訪問
	for v := 0; v < len(dg.g); v++ {
		if dg.g[u][v] == 0 {
			continue // 辺がなければスキップ
		}

		// vが未訪問なら訪問
		if dg.colors[v] == WHITE {
			dg.dfsVisit(v)
		}
	}

	// 頂点uを訪問済みに設定
	dg.colors[u] = BLACK
	time++
	dg.ftime[u] = time
}

func (dg dfsGraph) dfs() {
	for i := 0; i < len(dg.g); i++ {
		if dg.colors[i] == WHITE {
			dg.dfsVisit(i)
		}
	}
}

func (dg dfsGraph) printDfsTime() {
	for i := 0; i < len(dg.g); i++ {
		fmt.Printf("%d %d %d\n", i+1, dg.stime[i], dg.ftime[i])
	}
}

func main() {
	adj := makeAdjList()
	colors := make([]int, len(adj))
	stime := make([]int, len(adj))
	ftime := make([]int, len(adj))
	graph := dfsGraph{adj, colors, stime, ftime}
	graph.dfs()
	graph.printDfsTime()
}

C++: #include <iostream>

using namespace std;

int V[100][100];
int n;

int d[100];
int f[100];

int t = 1;
void dfs(int src){
  t++;
  for(int i=1;i<=n;i++){
    if(V[src][i] != 0 && !d[i]){
      d[i] = t;
      dfs(i);
      t++;
    }
  }
  f[src] = t;
}
int main(){
  int  src, dst, num, non_visited;
  cin >> n;
  for(int i=1;i<=n;i++){
    d[i] = 0; f[i] = 0;
  }
  for(int i=1;i<=n;i++){
    cin >> src >> num;
    for(int j=0;j<num;j++){
      cin >> dst;
      V[src][dst] = 1;
    }
  }
  non_visited = 1;
  do{
    d[non_visited] = t;
    dfs(non_visited);
    non_visited = 0;
    for(int i=1;i<=n;i++){
      if(!d[i]){
        non_visited = i;
        break;
      }
    }
    t++;
  }while(non_visited);

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

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

int G[110][110];///构造图
bool vis[110];///设置是否访问过
int tot;///设置访问次序
int st[110],ed[110];///设置顶点的发现时刻，顶点的结束时刻
int n;

int next_(int u){
    for(int i=1;i<=n;i++){
        if(G[u][i]&&vis[i]==0)
            return i;
    }
    return -1;
}

void DFS(int r){
    stack<int> s;
    s.push(r);
    vis[r]=true;
    st[r]=++tot;
    while(!s.empty()){
        int u=s.top();
        int v=next_(u);
        if(v!=-1){
            if(vis[v]==false){
                vis[v]=true;
                st[v]=++tot;
                s.push(v);
            }
        }
        else{
            s.pop();
            ed[u]=++tot;
        }

    }
}

void DFS_Visit(){
    memset(st,0,sizeof(st));
    memset(ed,0,sizeof(ed));
    memset(vis,0,sizeof(vis));
    tot=0;
    for(int i=1;i<=n;i++){
        if(vis[i]==false)
            DFS(i);
    }
    for(int i=1;i<=n;i++){
        printf("%d %d %d\n",i,st[i],ed[i]);
    }
}

int main(){
    scanf("%d",&n);
    memset(G,0,sizeof(G));

    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);
            G[u][v]=1;
        }
    }
    DFS_Visit();
    return 0;
}

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

using namespace std;

struct Node {
    int visit = 0;
    vector<int> next;
    int s = 0;
    int start = 0;
    int end = 0;
};

int main() {
    int n, id, k, temp, time = 1;
    Node node[101];
    stack<int> st;

    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> id >> k;
        for (int j = 0; j < k; j++) {
            cin >> temp;
            node[id].next.push_back(temp);
        }
    }

    while (1) {
        int s = -1;
        for (int i = 1; i <= n; i++) {
            if (node[i].visit == 0) {
                s = i;
                break;
            }
        }
        if (s == -1) {
            break;
        }
        
        node[s].start = time++;
        st.push(s);
        while (!st.empty()) {
            temp = st.top();
            if (node[temp].s < node[temp].next.size()) {
                if (node[node[temp].next[node[temp].s]].visit == 0) {
                    node[node[temp].next[node[temp].s]].start = time++;
                    node[node[temp].next[node[temp].s]].visit = 1;
                    st.push(node[temp].next[node[temp].s++]);
                }
                else {
                    node[temp].s++;
                }
            }
            else {
                node[temp].visit = 2;
                node[temp].end = time++;
                st.pop();
            }
        }
    }

    for (int i = 1; i <= n; i++) {
        cout << i << " " << node[i].start << " " << node[i].end << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <climits>
#include <string>
#include <vector>
#include <utility>
#include <functional>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <cassert>

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

#define REP(i, n) for (ll i = 0; i < n; i++)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOR(i, m, n) for (ll i = m; i < n; i++)

vector<int> g[101];
bool visited[101]{};
P ans[101];

int dfs(int s, int t){
    visited[s]=true;
    ans[s].first = t;
    REP(i,g[s].size()){
        if(visited[g[s][i]])continue;
        t = dfs(g[s][i],t+1);
    }
    t++;
    ans[s].second = t;
    return t;
}


int main() {
    int n;
    cin >> n;
    REP(i,n){
        int u,m;
        cin >> u >> m;
        REP(j,m){
            int v;
            cin >> v;
            g[u].push_back(v);
        }
    }
    dfs(1,1);
    for(int i=1;i<=n;i++){
        cout << i << " " << ans[i].first << " " << ans[i].second << endl;
    }
    return 0;
}

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

struct node {
    int start = 0;
    int end = 0;
};

void depth_search(map<int, vector<int> > &a, map<int, node> &nodes, int &time, int current) {
    time++;
    nodes[current].start = time;
    for (int i=0; i<a[current].size(); i++) {
        if ( nodes[a[current][i]].start == 0 ) {
            depth_search(a, nodes, time, a[current][i]);
        }
    }
    time++;
    nodes[current].end = time;
}

int main() {
    int n;
    cin >> n;
    map<int, vector<int> > a;
    for (int i=0; i<n; i++) {
        int u, k, v;
        cin >> u >> k;
        for (int j=0; j<k; j++) {
            cin >> v;
            a[u].push_back(v);
        }
    }
    
    int time = 0;
    map<int, node> nodes;
    for (int i=0; i<n; i++) {
        node nd; 
        nodes[i] = nd;
    }
    depth_search(a, nodes, time, 1);
    
    for (int i=1; i<=n; i++) {
        cout << i << " " << nodes[i].start << " " << nodes[i].end << endl;
    }
}