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

'''
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.
'''

class Solution:
    def minFlips(self, s: str) -> int:
        n=len(s)
        s=s+s
        tar1,tar2='01'*n,'10'*n
        a,b=0,0#a--->for unbalanced chars in tar1 simultaneously b for tar2
        for i in range(n):
            if tar1[i]!=s[i]:a+=1
            if tar2[i]!=s[i]:b+=1
        ans=float('inf')

        ans=min(ans,a,b)
        for i in range(n,2*n):
            if tar1[i-n]!=s[i-n]:a-=1
            if tar1[i]!=s[i]:a+=1
            if tar2[i-n]!=s[i-n]:b-=1
            if tar2[i]!=s[i]:b+=1
            ans=min(ans,a,b)
        return ans