K-letter Permutations

You are given a set \(S\) of \(n\) unique uppercase letters and an integer \(k\) such that \(1 \le k \le n\). Your task is to generate all possible k-letter permutations (ordered arrangements) using the letters from \(S\). The permutations must be printed in lexicographical order.

Note: Even though the term "combination" is sometimes used, here the order of letters matters, meaning that for a test case with \(S = \{A, B, C\}\) and \(k = 2\), the permutation "AB" is considered different from "BA".

For example, if \(k = 2\) and \(S = \{A, B, C\}\), after sorting \(S\) (which remains "ABC"), the possible permutations are:

[ AB, AC, BA, BC, CA, CB ]

Print the results as a single line for each test case, with the individual permutations separated by a single space.

inputFormat

The input is read from standard input (stdin) and has the following format:

T
k n letters
k n letters
... (T test cases in total)

Where:

• T is the number of test cases.
• For each test case, k is an integer representing the length of the permutation to generate.
• n is an integer indicating the number of letters in the provided set.
• letters is a string of n unique uppercase letters (not necessarily sorted).

outputFormat

For each test case, output a single line containing all the generated k-letter permutations separated by a single space, in lexicographical order.

## sample

1
2 3 ABC

AB AC BA BC CA CB

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