3. Numbers Game

Week 01
To have the full interactive experience, please view this video on itempool.
This lecture is based on the Numbers Game problem (Google Code Jam 2010 Round 1A, problem C), and you can find a link to it here.
This problem involves an interesting combinatorial game and requires no specific background to solve, although a lot of observations are involved in building up to the final answer. The solution involves the golden ratio, which you can find out more about here.
To find out more about combinatorial games in general you could start with this wiki on Brilliant, this chapter on Mathigon, and this wonderful talk by Prof R. Ramanujam.
The code discussed in the video can be found here.