Language: C++

#include<iostream>
using namespace std;

struct vertex
{
	int id;
	int discover;
	int finish;
	bool flag;
};

static int time = 1;

void DFS(int **arr, int n, int u , vertex *ver)
{
	ver[u - 1].flag = 1;
	ver[u - 1].discover = time;
	time++;
	for (int i = 0; i < n; i++)
	{
		if (u - 1 == i)
			continue;
		if (arr[u - 1][i] == 1 && ver[i].flag == 0)
		{
			DFS(arr, n, i + 1, ver);
			time++;
		}
	}
	ver[u - 1].finish = time;
}


int main()
{
	int n = 0;
	while (cin >> n)
	{
		int **arr = new int*[n];
		vertex *ver = new vertex[n];
		for (int i = 0; i < n; i++)
		{
			arr[i] = new int[n];
			for (int j = 0; j < n; j++)
			{
				arr[i][j] = 0;
			}
			ver[i].id = i + 1;
			ver[i].flag = 0;
		}
		for (int i = 0; i < n; i++)
		{
			int u = 0;
			int k = 0;
			int v = 0;
			cin >> u >> k;
			while (k--)
			{
				cin >> v;
				arr[u - 1][v - 1]++;
			}
		}
		for (int i = 0; i < n; i++)
		{
			if(ver[i].flag == 0)
				DFS(arr, n, i + 1, ver);
		}
		for (int i = 0; i < n; i++)
		{
			cout << ver[i].id << " " << ver[i].discover << " " << ver[i].finish << endl;
		}
		time = 1;
	}

	return 0;
}


Compiler output:
a.cc:12:12: error: 'int time' redeclared as different kind of entity
   12 | static int time = 1;
      |            ^~~~
In file included from /usr/include/pthread.h:23,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/gthr-default.h:35,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/gthr.h:157,
                 from /usr/include/c++/14/ext/atomicity.h:35,
                 from /usr/include/c++/14/bits/ios_base.h:39,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/time.h:76:15: note: previous declaration 'time_t time(time_t*)'
   76 | extern time_t time (time_t *__timer) __THROW;
      |               ^~~~
a.cc: In function 'void DFS(int**, int, int, vertex*)':
a.cc:17:31: error: invalid conversion from 'time_t (*)(time_t*) noexcept' {aka 'long int (*)(long int*) noexcept'} to 'int' [-fpermissive]
   17 |         ver[u - 1].discover = time;
      |                               ^~~~
      |                               |
      |                               time_t (*)(time_t*) noexcept {aka long int (*)(long int*) noexcept}
a.cc:18:9: warning: ISO C++ forbids incrementing a pointer of type 'time_t (*)(time_t*) noexcept' {aka 'long int (*)(long int*) noexcept'} [-Wpointer-arith]
   18 |         time++;
      |         ^~~~
a.cc:18:13: error: lvalue required as increment operand
   18 |         time++;
      |             ^~
a.cc:26:25: warning: ISO C++ forbids incrementing a pointer of type 'time_t (*)(time_t*) noexcept' {aka 'long int (*)(long int*) noexcept'} [-Wpointer-arith]
   26 |                         time++;
      |                         ^~~~
a.cc:26:29: error: lvalue required as increment operand
   26 |                         time++;
      |                             ^~
a.cc:29:29: error: invalid conversion from 'time_t (*)(time_t*) noexcept' {aka 'long int (*)(long int*) noexcept'} to 'int' [-fpermissive]
   29 |         ver[u - 1].finish = time;
      |                             ^~~~
      |                             |
      |                             time_t (*)(time_t*) noexcept {aka long int (*)(long int*) noexcept}
a.cc: In function 'int main()':
a.cc:71:22: error: assignment of function 'time_t time(time_t*)'
   71 |                 time = 1;
      |                 ~~~~~^~~