1332\. Remove Palindromic Subsequences

Easy

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'`.