This is the hard version of the problem. The only difference between the easy and hard versions is that in the hard one, there are no constraints on the number of employees in every department.

ChefCorp has N employees. Each employee belongs to exactly one of the M departments. Each department is headed by exactly one of the employees belonging to that department.

The management structure of ChefCorp is as follows:
Each employee of a department (including its head) is *in contact* with every other employee of that department.
The head of each department is *in contact* with the heads of all the other departments.

For example, let N = 7, M = 3 and employees 1, \textbf{2}, 3 belong to the first department, employees \textbf{4}, 5 belong to the second department and employees \textbf{6}, 7 belong to the third department (employees in bold represent the heads of the departments). The following pairs of employees are in contact with each other: (1, 2), (1, 3), (2, 3), (4, 5), (6, 7), (2, 4), (4, 6), (2, 6).

However, due to some inexplicable reasons, ChefCorp loses all its data on the departments. Given the total number of employees N and every pair of employees who are *in contact* with each other, can you help recover the number of departments and the employees belonging to each of the departments?

------ Input Format ------ 

- The first line contains a single integer T — the number of test cases. Then the test cases follow.
- The first line of each test case contains a single integer N — the total number of employees in ChefCorp.
- The second line of each test case contains a single integer K — the number of pairs of employees *in contact* with each other.
- K lines follow. The i^{th} of these K lines contain two space-separated integers u_{i} and v_{i}, denoting that employee u_{i} is *in contact* with v_{i}.

------ Output Format ------ 

- For each test case, output the following:
- In the first line output M — the number of departments.
- In the second line, output N space-separated integers D_{1}, D_{2}, \ldots, D_{N} (1 ≤ D_{i} ≤ M) — denoting that the i^{th} employee belongs to the D_{i}^{th} department.
- In the third line, output M space-separated integers H_{1}, H_{2}, \ldots, H_{M} (1 ≤ H_{i} ≤ N, H_{i} \neq H_{j} when i \neq j) — denoting that the H_{i}^{th} employee is the head of the i^{th} department.

If there are multiple answers, output any. It is guaranteed that at least one solution always exists.

------ Constraints ------ 

$1 ≤ T ≤ 1000$
$2 ≤ N ≤ 1000$
$1 ≤ K ≤ \frac{N\cdot(N-1)}{2}$
$1 ≤ u_{i}, v_{i} ≤ N$
$u_{i} \neq v_{i}$ for each $1 ≤ i ≤ K$.
- The sum of $N$ over all test cases does not exceed $3000$.

----- Sample Input 1 ------ 
4
7
8
1 2
1 3
2 3
4 5
6 7
2 4
4 6
2 6
2
1
1 2
3
2
3 2
3 1
6
8
6 2
5 4
3 1
5 2
3 6
2 1
6 1
2 3

----- Sample Output 1 ------ 
3
1 1 1 2 2 3 3
2 4 6
2
1 2
1 2
2
1 2 1
3 2
2
1 1 1 2 2 1
2 5

----- explanation 1 ------ 
Test case 1: Explained in the problem statement.

Source: codechef | Difficulty: VERY_HARD
Tags: Graph algorithms

Data structures


Solutions:
tc = int(input())
for _ in range(tc):
	n = int(input())
	k = int(input())
	adjl = [set() for _ in range(n)]
	for i in range(k):
		(u, v) = map(int, input().split())
		adjl[u - 1].add(v - 1)
		adjl[v - 1].add(u - 1)
	maxd = 0
	md = -1
	for i in range(n):
		if len(adjl[i]) > maxd:
			maxd = len(adjl[i])
			md = i
	mf = False
	for v in adjl[md]:
		p = set(adjl[v])
		p.remove(md)
		p.add(v)
		if len(p.difference(adjl[md])) != 0:
			managers = adjl[md].intersection(p)
			mf = True
			break
	if not mf:
		managers = p
	managers.add(md)
	m = len(managers)
	print(m)
	d = [0 for i in range(n)]
	k = 1
	manx = list(managers)
	for tm in manx:
		d[tm] = k
		for v in adjl[tm]:
			if not v in managers:
				d[v] = k
		k += 1
	print(*d)
	print(*[t + 1 for t in manx])