1332. Remove Palindromic Subsequences

https://leetcode.com/problems/remove-palindromic-subsequences

Description

You are given a string s consisting only of letters 'a' and 'b'. In a single step you can remove one palindromic subsequence from s.

Return the minimum number of steps to make the given string empty.

A string is a subsequence of a given string if it is generated by deleting some characters of a given string without changing its order. Note that a subsequence does not necessarily need to be contiguous.

A string is called palindrome if is one that reads the same backward as well as forward.

Example 1:

**Input:** s = "ababa"
**Output:** 1
**Explanation:** s is already a palindrome, so its entirety can be removed in a single step.

Example 2:

**Input:** s = "abb"
**Output:** 2
**Explanation:** "abb" -> "bb" -> "". 
Remove palindromic subsequence "a" then "bb".

Example 3:

**Input:** s = "baabb"
**Output:** 2
**Explanation:** "baabb" -> "b" -> "". 
Remove palindromic subsequence "baab" then "b".

Constraints:

• 1 <= s.length <= 1000

• s[i] is either 'a' or 'b'.

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