Programming

1. Implement an algorithm to tell if a string has all unique characters.

2. Given two strings, write a method to tell if one is a permutation of the other.

3. Write a method to do basic string compression using the counts of repeated characters. For example, the string "aaabbbcccca" would become "a3b3c4a". If the string would not be shorter after this compression, return the original string. You can assume you will only receive strings with upper and lowercase (a-z).