Implement stacks, with tests.
Updated linked_list.rb, don

;alksjf;sldkjf
Implement queues.
Implement binary trees, with tests.
Refactor search methods.
Implement insertion sort, with tests.
Implement merge sort, with tests.
Forgot to update README.
Optimized merge sort case where l or r is 0.
Improve merge sort a little.
Trying crazy things.
Implement quick sort, with tests.
Tweak algorithms for speed a bit.
Implement radix sort, wi, with tests.
Add doubly-linked lists, with tests (that are stupid).
Refactored deduplicate (with array), fixed tests.
Save before making an new branch.
Implement hash map, with tests.
Add inserts and contains functions.
Implement binary search tree, with tests.