1513. Number of Substrings With Only 1s

https://leetcode.com/problems/number-of-substrings-with-only-1s

Description

Given a binary string s (a string consisting only of '0' and '1's).

Return the number of substrings with all characters 1's.

Since the answer may be too large, return it modulo 10^9 + 7.

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.

Example 4:

**Input:** s = "000"

**Output:** 0

Constraints:

• s[i] == '0' or s[i] == '1'

• 1 <= s.length <= 10^5

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