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.

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.

class Solution {
public:
    int minFlips(string& s) {
        int len(s.length()), res(0), cur(0);
        s += s;
        for(int i = 0; i < len; i++) {
            if((s[i] & 0b1111) != (i & 1)) cur += s[i] = 1;
            else s[i] = 0;
        }
        res = min(cur, len - cur);
        for(int i = len; i < len<<1 and res; i++) {
            if((s[i] & 0b1111) != (i & 1)) ++cur;
            cur -= s[i - len];
            res = min(res, min(cur, len - cur));
        }

        return res;
    }
};