Brain Storming

Brain Storming
It is always joyful to realize that I am thinking by myself!
Never let others to think for you.

Here is two web sites which is very suitable and challenge for my level!
Problem of the Week
Harvard University
As stated in the title, those problems are very time consuming.
http://www.physics.harvard.edu/academics/undergrad/problems.html

Puzzle Toad
Carnegie Mellon University
Puzzles of Computer Science
http://www.cs.cmu.edu/puzzle/index.html

Those two should keep me busy for a while!