> For the complete documentation index, see [llms.txt](https://jaywin.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jaywin.gitbook.io/leetcode/solutions/1653-minimum-deletions-to-make-string-balanced.md).

# 1653. Minimum Deletions to Make String Balanced

<https://leetcode.com/problems/minimum-deletions-to-make-string-balanced>

## Description

You are given a string `s` consisting only of characters `'a'` and `'b'`​​​​.

You can delete any number of characters in `s` to make `s` **balanced**. `s` is **balanced** if there is no pair of indices `(i,j)` such that `i < j` and `s[i] = 'b'` and `s[j]= 'a'`.

Return *the **minimum** number of deletions needed to make* `s` ***balanced***.

**Example 1:**

```
**Input:** s = "aababbab"
**Output:** 2
**Explanation:** You can either:
Delete the characters at 0-indexed positions 2 and 6 ("aababbab" -> "aaabbb"), or
Delete the characters at 0-indexed positions 3 and 6 ("aababbab" -> "aabbbb").
```

**Example 2:**

```
**Input:** s = "bbaaaaabb"
**Output:** 2
**Explanation:** The only solution is to delete the first two characters.
```

**Constraints:**

* `1 <= s.length <= 105`
* `s[i]` is `'a'` or `'b'`​​.

## ac

```java
```