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Re: Australian Mathematical Society  Hat Puzzle
Posted:
Mar 3, 2013 2:50 PM


On Sun, 3 Mar 2013 11:35:41 0800 (PST), Pratik Poddar wrote:
>Posted on: http://pratikpoddarcse.blogspot.com/2013/02/madhatparty.html > >Problem: The Mad Hatter is holding a hat party, where every >guest must bring his or her own hat. At the party, whenever two guests greet each other, they have to swap their hats. In order to save time, each pair of guests is only allowed to greet each other at most once. > >After a plethora of greetings, the Mad Hatter notices that it is no longer possible to return all hats to their respective owners through more greetings. To sensibly resolve this maddening conundrum, he decides to bring in even more hat wearing guests, to allow for even more greetings and hat swappings. How many extra guests are needed to return all hats (including the extra ones) to their rightful owners? > >About the blog: CSE Blog ( http://pratikpoddarcse.blogspot.com ) is a collection of 225+ Quant, Math & Computer Science Puzzles for Interview Preparation & Brain Teasing with Solution. It has had more than 300,000 page views since last 3 years. I hope you will enjoy it. Cheers!
How sociable are the guests? Maybe they don't meet every other guest.
Must a guest exchange hats with the host when they meet?
May a guest exchange hats with the host? If so, how many times may the host exchange hats with a guest? If there is no restriction on the host's actions, no extra guests are needed.



