# 1525. Number of Good Ways to Split a String

<https://leetcode.com/problems/number-of-good-ways-to-split-a-string>

## Description

You are given a string `s`, a split is called *good* if you can split `s` into 2 non-empty strings `p` and `q` where its concatenation is equal to `s` and the number of distinct letters in `p` and `q` are the same.

Return the number of *good* splits you can make in `s`.

**Example 1:**

```

**Input:** s = "aacaba"
**Output:** 2
**Explanation:** There are 5 ways to split "aacaba" and 2 of them are good. 
("a", "acaba") Left string and right string contains 1 and 3 different letters respectively.
("aa", "caba") Left string and right string contains 1 and 3 different letters respectively.
("aac", "aba") Left string and right string contains 2 and 2 different letters respectively (good split).
("aaca", "ba") Left string and right string contains 2 and 2 different letters respectively (good split).
("aacab", "a") Left string and right string contains 3 and 1 different letters respectively.
```

**Example 2:**

```

**Input:** s = "abcd"
**Output:** 1
**Explanation:** Split the string as follows ("ab", "cd").
```

**Example 3:**

```

**Input:** s = "aaaaa"
**Output:** 4
**Explanation:** All possible splits are good.
```

**Example 4:**

```

**Input:** s = "acbadbaada"
**Output:** 2
```

**Constraints:**

* `s` contains only lowercase English letters.
* `1 <= s.length <= 10^5`

## ac

```java
```