Of Mindsport and other things...

A couple of weeks ago, one of my posts mentioned Mindsport, which for those who came in late, is a weekly puzzle column that turns up every Sunday in The Sunday Times. Anyway, the subject of my post was my sending in a ludicrously simple solution to one of the puzzles. Now every week the writer complains about people demanding that their solution be published, since they've sent in 3000 solutions already, etc...Apparently only a few make it to the actual column - not surprising, since it's so tiny.

Anyway, you can imagine my surprise when I began reading yesterday's Mindsport, and found a suspiciously familiar train of comments. Sure enough, there it was - my solution, along with my ranting that it was too easy, barely worth five minutes, etc...Wonderful - my first solution, and it gets published too!

For those who want the question, here it is:

Consider N chairs, numbered 1 to N, arranged in a circle. Two people, A and B, are initially in chair 1(don't ask me how...). At every stage, A moves 'a' chairs around the circle, and B moves 'b' chairs around the circle. How many moves before A and B end up in the same chair again?

It's fairly simple, took less than 5 minutes to work out...(Note to Sagar: This might be good practice for the CAT, provided you can work it out in less than a minute...Of course, they'll probably give you real numbers...)

Check out my solution in the Sunday Times if you don't get it...and if you don't get the Sunday times, drop me a line...

News Flash: Had my first bhutta(Corn on the cob, Indian style) for this rainy season...Yum!

Next up: solve the recurrence Q_n = (1 + Q_n-1)/Q_n-2, where Q₀ = α and Q₁ = β...Interesting, it repeats in cycles of 5...

For those greedy for more intellectual stimulation, here's a little variation on the Towers of Hanoi problem that I was working on yesterday: Move n disks from the left pole(A) to the right pole(B), but without direct moves between A and B. All moves must be to or from the middle pole(C). The layout is obviously A C B. As usual, larger disks cannot be placed on top of smaller ones.

Final verdict: Recurrences rock!