Here is the list of events from Hackerrank,Hackerearth and Codechef.

Here is an helpful extension for your desktop for notifications.!

WebStore link for Chrome Extension.

Note: You can add this to your Calender by clicking on the right bottom button.This adds all the upcoming events to your calender and notifies you about the events.

This Calender is updated Automatically.
You can Bookmark this link.