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3518. Smallest Palindromic Rearrangement II
Description
You are given a palindromic string s and an integer k.
Return the k-th lexicographically smallest palindromic permutation of s. If there are fewer than k distinct palindromic permutations, return an empty string.
Note: Different rearrangements that yield the same palindromic string are considered identical and are counted once.
Example 1:
Input: s = "abba", k = 2
Output: "baab"
Explanation:
- The two distinct palindromic rearrangements of "abba"are"abba"and"baab".
- Lexicographically, "abba"comes before"baab". Sincek = 2, the output is"baab".
Example 2:
Input: s = "aa", k = 2
Output: ""
Explanation:
- There is only one palindromic rearrangement: "aa".
- The output is an empty string since k = 2exceeds the number of possible rearrangements.
Example 3:
Input: s = "bacab", k = 1
Output: "abcba"
Explanation:
- The two distinct palindromic rearrangements of "bacab"are"abcba"and"bacab".
- Lexicographically, "abcba"comes before"bacab". Sincek = 1, the output is"abcba".
Constraints:
- 1 <= s.length <= 104
- sconsists of lowercase English letters.
- sis guaranteed to be palindromic.
- 1 <= k <= 106