Test added and findNode fixed with O(1) complexity

[virenvarma007]

No description provided.

[jordanmontt]

Thanks @virenvarma007 !

Some observations:

• Could you find another name for the instance variable dictNodes ? please
• Can you format the code?
• The test is good, but can you rename testdictNodes to something else? Also, can you add other tests that.
  1. The test does not call the run method. Only test that setting and getting the nodes works well.
  2. Some other tests that test only one simple thing