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# 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'`.

## ac

```java
```