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Funny Permutation

1000ms 262144K

Description:

A sequence of $$$n$$$ numbers is called permutation if it contains all numbers from $$$1$$$ to $$$n$$$ exactly once. For example, the sequences $$$[3, 1, 4, 2]$$$, [$$$1$$$] and $$$[2,1]$$$ are permutations, but $$$[1,2,1]$$$, $$$[0,1]$$$ and $$$[1,3,4]$$$ are not.

For a given number $$$n$$$ you need to make a permutation $$$p$$$ such that two requirements are satisfied at the same time:

  • For each element $$$p_i$$$, at least one of its neighbors has a value that differs from the value of $$$p_i$$$ by one. That is, for each element $$$p_i$$$ ($$$1 \le i \le n$$$), at least one of its neighboring elements (standing to the left or right of $$$p_i$$$) must be $$$p_i + 1$$$, or $$$p_i - 1$$$.
  • the permutation must have no fixed points. That is, for every $$$i$$$ ($$$1 \le i \le n$$$), $$$p_i \neq i$$$ must be satisfied.

Let's call the permutation that satisfies these requirements funny.

For example, let $$$n = 4$$$. Then [$$$4, 3, 1, 2$$$] is a funny permutation, since:

  • to the right of $$$p_1=4$$$ is $$$p_2=p_1-1=4-1=3$$$;
  • to the left of $$$p_2=3$$$ is $$$p_1=p_2+1=3+1=4$$$;
  • to the right of $$$p_3=1$$$ is $$$p_4=p_3+1=1+1=2$$$;
  • to the left of $$$p_4=2$$$ is $$$p_3=p_4-1=2-1=1$$$.
  • for all $$$i$$$ is $$$p_i \ne i$$$.

For a given positive integer $$$n$$$, output any funny permutation of length $$$n$$$, or output -1 if funny permutation of length $$$n$$$ does not exist.

Input:

The first line of input data contains a single integer $$$t$$$ ($$$1 \le t \le 10^4$$$) — the number of test cases.

The description of the test cases follows.

Each test case consists of f single line containing one integer $$$n$$$ ($$$2 \le n \le 2 \cdot 10^5$$$).

It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^5$$$.

Output:

For each test case, print on a separate line:

  • any funny permutation $$$p$$$ of length $$$n$$$;
  • or the number -1 if the permutation you are looking for does not exist.

Sample Input:

5
4
3
7
5
2

Sample Output:

3 4 2 1
-1
6 7 4 5 3 2 1
5 4 1 2 3
2 1

Note:

The first test case is explained in the problem statement.

In the second test case, it is not possible to make the required permutation: permutations $$$[1, 2, 3]$$$, $$$[1, 3, 2]$$$, $$$[2, 1, 3]$$$, $$$[3, 2, 1]$$$ have fixed points, and in $$$[2, 3, 1]$$$ and $$$[3, 1, 2]$$$ the first condition is met not for all positions.

Informação

Codeforces

Provedor Codeforces

Código CF1741B

Tags

constructive algorithmsmath

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Datas 09/05/2023 10:32:50

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