Nothing much , its just a solution for an interview question I saw it in social media ( from Microsoft I think ) . The problem is that we have a sequence of repeated characters ( EX: AAAABBBBBCCCCCCC ) we want to compresse it , while still being able to expand it back to the original one. My solution to this problem is using patterns, taking the number of how many times a character have being repeated and put in the new sentence in a certaine way using '*' and '.' to organize the sequence. check the code for more information and to understand it more. I made the two algorithems , the compressing and the decompressing one.