(HARD) Given an input String with a mixture of letters and other characters and an ArrayList of words to look for, plus a threshold number, find and return a message containing "stretched" anagrams in the input from the word list separated by spaces. A stretched anagram is a sequence of letters that contains all the letters in another word, but may have a few extra letters as well. So for example while "card" cannot be found in "cart", it is possible to find "card" within "Cart a dumbell around" if the threshold value is 2 (expand the search for "card" to include up to 2 extra letters). Note that the words ArrayList is going to contain a bunch of extra words that cannot be found in the input, even stretched: your task is to find and sequence only the words that are found.

Seeing the problems before this one, perhaps you have been wondering what a bunch of anagram problems are doing in a set about encryption. Now you have an answer: you are coding a technique for steganography, hiding secret information within seemingly-innocent other information. Most students are introduced to steganography through digital photo manipulation, but text is also everywhere, and techniques for textual steganography have been employed for a very long time.

Preconditions: words contains Strings of only lowercase letters. The threshold value will be greater than or equal to 0. (A threshold of 0 means that the anagrams will be found with no extra letters, as in the earlier apcsaIndexOfAnagram problem.)

HINT: because of the stretching threshold, you are likely to "find" the same word multiple times starting at consecutive locations. How do you deal with that possibility?

HELPFUL TIP: when making output that joins together an ArrayList into a String, use String.join(String separator, List words) such as String.join(" ", words)