3378. Hidden Anagrams

An anagram is a word or a phrase that is formed by rearranging the letters of another. For instance, by rearranging the letters of William Shakespeare, we can have its anagrams I am a weakish speller, I'll make a wise phrase, and so on. Note that when A is an anagram of B, B is an anagram of A.

In the above examples, di erences in letter cases are ignored, and word spaces and punctuation symbols are freely inserted and/or removed. These rules are common but not applied here; only exact matching of the letters is considered.

For two strings $s_1$ and $s_2$ of letters, if a substring $s’_1$ of $s_1$ is an anagram of a substring $s’_2$ of $s_2$, we call $s’_1$ a hidden anagram of the two strings, $s_1$ and $s_2$. Of course, $s’_2$ is also a hidden anagram of them.

Your task is to write a program that, for given two strings, computes the length of the longest hidden anagrams of them.

Suppose, for instance, that anagram and grandmother are given. Their substrings nagr and gran are hidden anagrams since by moving letters you can have one from the other. They are the longest since any substrings of grandmother of lengths ve or more must contain d or o that anagram does not. In this case, therefore, the length of the longest hidden anagrams is four. Note that a substring must be a sequence of letters occurring consecutively in the original string and so nagrm and granm are not hidden anagrams.