Given a string S
, return the number of substrings that have only one distinct letter.
Example 1:
Input: S = "aaaba" Output: 8 Explanation: The substrings with one distinct letter are "aaa", "aa", "a", "b". "aaa" occurs 1 time. "aa" occurs 2 times. "a" occurs 4 times. "b" occurs 1 time. So the answer is 1 + 2 + 4 + 1 = 8.
Example 2:
Input: S = "aaaaaaaaaa" Output: 55
Constraints:
1 <= S.length <= 1000
S[i]
consists of only lowercase English letters.