Package g2201_2300.s2222_number_of_ways_to_select_buildings

Class Solution

java.lang.Object
g2201_2300.s2222_number_of_ways_to_select_buildings.Solution
public class Solution extends java.lang.Object
2222 - Number of Ways to Select Buildings.

Medium

You are given a 0-indexed binary string s which represents the types of buildings along a street where:

  • s[i] = '0' denotes that the ith building is an office and
  • s[i] = '1' denotes that the ith building 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.

  • For example, given s = "0**0**1**1**0**1**", we cannot select the 1st, 3rd, and 5th buildings as that would form "0**11**" which is not allowed due to having two consecutive buildings of the same type.

Return the number of valid ways to select 3 buildings.

Example 1:

Input: s = “001101”

Output: 6

Explanation: The following sets of indices selected are valid:

  • [0,2,4] from “001101” forms “010”

  • [0,3,4] from “001101” forms “010”

  • [1,2,4] from “001101” forms “010”

  • [1,3,4] from “001101” forms “010”

  • [2,4,5] from “001101” forms “101”

  • [3,4,5] from “001101” forms “101”

No other selection is valid. Thus, there are 6 total ways.

Example 2:

Input: s = “11100”

Output: 0

Explanation: It can be shown that there are no valid selections.

Constraints:

  • 3 <= s.length <= 105
  • s[i] is either '0' or '1'.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    numberOfWays(java.lang.String s)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • numberOfWays

      public long numberOfWays(java.lang.String s)