Minimum Swap Distance

Two strings source and target are said to have a swap distance of d if exactly d two-character position swaps in source are required to transform it into target. In each swap operation, you select two positions i and j in the string and exchange the characters at those positions.

Given two strings source and target that are guaranteed to be anagrams of each other (meaning they contain identical characters with the same frequencies), determine the minimum swap distance required to convert source into target.

Your goal is to find the smallest number of swap operations that will transform the source string into the target string. This is a classic string transformation problem that requires careful analysis of character misplacements and optimal swap sequencing.

The key insight is that when two characters are in the wrong positions relative to each other, a single swap can correct both simultaneously. However, when characters form longer cycles of misplacements, more swaps are needed. Finding the optimal sequence of swaps to minimize the total count is the core challenge of this problem.