1. find all the combinations of a string in lowercase and uppercase. For example, string "ab" -> "ab", "Ab", "aB", "AB". So, you will have 2^n (n = number of chars in the string) output strings. The goal is for you to test each of these string and see if it match a hidden string. 2. Implement a simple regex parser which, given a string and a pattern, returns a boolean indicating whether the input matches the pattern. By simple, we mean that the regex can only contain special character: * (star), . (dot), + (plus). The star means what you'd expect, that there will be zero or more of previous character in that place in the pattern. The dot means any character for that position. The plus means one or more of previous character in that place in the pattern.