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1888. Minimum Number of Flips to Make the Binary String Alternating 👍

Problem

You are given a binary string s. You are allowed to perform two types of operations on the string in any sequence:

  • Type-1: Remove the character at the start of the string s and append it to the end of the string.
  • Type-2: Pick any character in s and flip its value, i.e., if its value is '0' it becomes '1' and vice-versa.

Return the minimum number of type-2 operations you need to perform such that s becomes alternating.

The string is called alternating if no two adjacent characters are equal.

  • For example, the strings "010" and "1010" are alternating, while the string "0100" is not.

 

Example 1:

Input: s = "111000"
Output: 2
Explanation: Use the first operation two times to make s = "100011".
Then, use the second operation on the third and sixth elements to make s = "101010".

Example 2:

Input: s = "010"
Output: 0
Explanation: The string is already alternating.

Example 3:

Input: s = "1110"
Output: 1
Explanation: Use the second operation on the second element to make s = "1010".

 

Constraints:

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