public class Solution
extends Object
1759 - Count Number of Homogenous Substrings\.
Medium
Given a string `s`, return _the number of **homogenous** substrings of_ `s`_._ Since the answer may be too large, return it **modulo** 109 + 7.
A string is **homogenous** if all the characters of the string are the same.
A **substring** is a contiguous sequence of characters within a string.
**Example 1:**
**Input:** s = "abbcccaa"
**Output:** 13
**Explanation:** The homogenous substrings are listed as below:
"a" appears 3 times.
"aa" appears 1 time.
"b" appears 2 times.
"bb" appears 1 time.
"c" appears 3 times.
"cc" appears 2 times.
"ccc" appears 1 time.
3 + 1 + 2 + 1 + 3 + 2 + 1 = 13.
**Example 2:**
**Input:** s = "xy"
**Output:** 2
**Explanation:** The homogenous substrings are "x" and "y".
**Example 3:**
**Input:** s = "zzzzz"
**Output:** 15
**Constraints:**
* 1 <= s.length <= 105
* `s` consists of lowercase letters.