Lexicographically Smallest Beautiful String
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Description
A string is beautiful if:
- It consists of the first k letters of the English lowercase alphabet.
- It does not contain any substring of length 2 or more which is a palindrome.
You are given a beautiful string s of length n and a positive integer k.
Return the lexicographically smallest string of length n, which is larger than s and is beautiful. If there is no such string, return an empty string.
A string a is lexicographically larger than a string b (of the same length) if in the first position where a and b differ, a has a character strictly larger than the corresponding character in b.
- For example, "abcd" is lexicographically larger than "abcc" because the first position they differ is at the fourth character, and d is greater than c.
Example 1:
Example 2:
Solution