challenge.txt

In any language(s) of your choice, write a working function that removes all duplicates from an unsorted list of email addresses. You may assume any input data structure that you like. Do not use built-in library functions that make the problem trivial. Do not google any answers to this, I want to see your own implementation.

Requirements:

Leave the resulting list in the original order (same as the input).
The function should be able to handle 100,000 email addresses containing 50% randomly placed duplicates in well under 1 second on a typical modern laptop.
Please include a simple test suite that demonstrates the above two requirements are met.
Please deploy a demo live on the web somewhere for us to see. This should include your own simple frontend, not just a jsfiddle or repl.it. It is totally fine to put it up as a free heroku node for example. Send us both the deployed URL and the source code.