Number of Ways to Select Buildings
You are given a 0-indexed binary string s which represents the types of buildings along a street where:
s[i] = '0'denotes that thei^thbuilding is an office.s[i] = '1'denotes that thei^thbuilding is a restaurant.
As a city official, you would like to select 3 buildings for random inspection. However, to ensure variety, no two consecutive buildings out of the selected buildings can be of the same type.
Return the number of valid ways to select 3 buildings.
Example 1
Input
s = "001101"Output
6The valid selections form either
010 or 101, and there are 6 total ways.Example 2
Input
s = "11100"Output
0It can be shown that there are no valid selections.
Constraints
- 3 <= s.length <= 10^5
- s[i] is either '0' or '1'.