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

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'.
```

- code

```
class Solution:
def removePalindromeSub(self, s: str) -> int:
if not s: return 0
return 1 if s == s[::-1] else 2
```