Strings A and B are K-similar (for some
non-negative integer K) if we can swap the positions of two letters in
A exactly K times so that the resulting string equals
B.
Given two anagrams A and B, return the smallest K for
which A and B are K-similar.
Example 1:
Input: A = "ab", B = "ba" Output: 1
Example 2:
Input: A = "abc", B = "bca" Output: 2
Example 3:
Input: A = "abac", B = "baca" Output: 2
Example 4:
Input: A = "aabc", B = "abca" Output: 2