1759. Count Number of Homogenous Substrings

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.