Solutions for Cracking the Coding Interview 6th Edition - Ruby Arrays and String Is Unique, RSpec tests Check Permutation, RSpec tests URLify, RSpec tests One Away, RSpec tests String Compression, RSpec tests Rotate Matrix, RSpec tests Zero Matrix, RSpec tests String Rotation, RSpec tests Linked List Delete Middle Node, RSpec tests Stacks and Queues Three in One, RSpec tests Stack Min, RSpec tests Stack of Plates, RSpec tests