1513. Number of Substrings With Only 1s
Given a binary string s, return the number of substrings with all characters 1's. Since the answer may be too large, return it modulo 109 + 7.
Examples
Example 1
Input: s = "0110111"
Output: 9
Explanation: There are 9 substring in total with only 1's characters.
"1" -> 5 times.
"11" -> 3 times.
"111" -> 1 time.
Example 2
Input: s = "101"
Output: 2
Explanation: Substring "1" is shown 2 times in s.
Example 3
Input: s = "111111"
Output: 21
Explanation: Each substring contains only 1's characters.
Constraints
1 <= s.length <= 105s[i] is either '0' or '1'.