# 1297. Maximum Number of Occurrences of a Substring

<https://leetcode.com/problems/maximum-number-of-occurrences-of-a-substring>

## Description

Given a string `s`, return the maximum number of ocurrences of **any** substring under the following rules:

* The number of unique characters in the substring must be less than or equal to `maxLetters`.
* The substring size must be between `minSize` and `maxSize` inclusive.

**Example 1:**

```

**Input:** s = "aababcaab", maxLetters = 2, minSize = 3, maxSize = 4
**Output:** 2
**Explanation:** Substring "aab" has 2 ocurrences in the original string.
It satisfies the conditions, 2 unique letters and size 3 (between minSize and maxSize).
```

**Example 2:**

```

**Input:** s = "aaaa", maxLetters = 1, minSize = 3, maxSize = 3
**Output:** 2
**Explanation:** Substring "aaa" occur 2 times in the string. It can overlap.
```

**Example 3:**

```

**Input:** s = "aabcabcab", maxLetters = 2, minSize = 2, maxSize = 3
**Output:** 3
```

**Example 4:**

```

**Input:** s = "abcde", maxLetters = 2, minSize = 3, maxSize = 3
**Output:** 0
```

**Constraints:**

* `1 <= s.length <= 10^5`
* `1 <= maxLetters <= 26`
* `1 <= minSize <= maxSize <= min(26, s.length)`
* `s` only contains lowercase English letters.

## ac

```java
```