break-a-palindrome

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1328. Break a Palindrome (Medium)

Given a palindromic string palindrome, replace exactly one character by any lowercase English letter so that the string becomes the lexicographically smallest possible string that isn't a palindrome.

After doing so, return the final string.  If there is no way to do so, return the empty string.

 

Example 1:

Input: palindrome = "abccba"
Output: "aaccba"

Example 2:

Input: palindrome = "a"
Output: ""

 

Constraints:

• 1 <= palindrome.length <= 1000
• palindrome consists of only lowercase English letters.

Related Topics

[String]

Hints

Hint 1

How to detect if there is impossible to perform the replacement? Only when the length = 1.

Hint 2

Change the first non 'a' character to 'a'.

Hint 3

What if the string has only 'a'?

Hint 4

Change the last character to 'b'.