1864. Minimum Number of Swaps to Make the Binary String Alternating

class Solution:
    def minSwaps(self, s: str) -> int:
        s0n0 = s0n1 = s1n0 = s1n1 = 0
        for i in range(len(s)):
            if (i & 1) == 0:
                if s[i] != '0':
                    s0n0 += 1
                else:
                    s1n1 += 1
            else:
                if s[i] != '0':
                    s1n0 += 1
                else:
                    s0n1 += 1
        if s0n0 != s0n1 and s1n0 != s1n1:
            return -1
        if s0n0 != s0n1:
            return s1n0
        if s1n0 != s1n1:
            return s0n0
        return min(s0n0, s1n0)