3470. Permutations IV

Given two integers, n and k, an alternating permutation is a permutation of the first n positive integers such that no two adjacent elements are both odd or both even. Return the k-th alternating permutation sorted in lexicographical order. If there are fewer than k valid alternating permutations, return an empty list. Example 1: Input: n = 4, k = 6 Output: [3,4,1,2] Explanation: The lexic