1750 - Minimum Length of String After Deleting Similar Ends.

Medium

Given a string s consisting only of characters 'a', 'b', and 'c'. You are asked to apply the following algorithm on the string any number of times:

• Pick a non-empty prefix from the string s where all the characters in the prefix are equal.

• Pick a non-empty suffix from the string s where all the characters in this suffix are equal.

• The prefix and the suffix should not intersect at any index.

• The characters from the prefix and suffix must be the same.

• Delete both the prefix and the suffix.

Return the minimum length of s after performing the above operation any number of times (possibly zero times).

Example 1:

Input: s = "ca"

Output: 2

Explanation: You can't remove any characters, so the string stays as is.

Example 2:

Input: s = "cabaabac"

Output: 0

Explanation: An optimal sequence of operations is:

• Take prefix = "c" and suffix = "c" and remove them, s = "abaaba".

• Take prefix = "a" and suffix = "a" and remove them, s = "baab".

• Take prefix = "b" and suffix = "b" and remove them, s = "aa".

• Take prefix = "a" and suffix = "a" and remove them, s = "".

Example 3:

Input: s = "aabccabba"

Output: 3

Explanation: An optimal sequence of operations is:

• Take prefix = "aa" and suffix = "a" and remove them, s = "bccabb".

• Take prefix = "b" and suffix = "bb" and remove them, s = "cca".

Constraints:

• <code>1 <= s.length <= 10⁵</code>

• s only consists of characters 'a', 'b', and 'c'.