Monday, February 20, 2006

Interview puzzle questions

So, for some random reason the other night we (I will say no more than we were a small group and out drinking) started to talk about using puzzle questions in interviews.

One question that a friend uses goes something like this:
  • In a tournament where there are 80 teams how many matches (where a match is between two teams) are played before the winner is decided ?
Personally, I don't like using mathematical puzzles in interviews as I feel they are quite artificial (I remember having the hardest time with some pure maths in uni but no problem at all when seeing the same ideas in quantum theory (ok, so you could argue that I had already been exposed to them, but I do think that framing alone (e.g. abstract vs practical) can quite significantly alter the ability of someone to "get a grip" on the problem at hand - and let's face it there are lots of people who don't think the same way (I know this from personal experience :-) ).

Anyway, my gut feeling is that if you get the answer right then the interviewer assumes you had seen it before (as my friend did when I worked it out mid-pint) and if you get it wrong they use it to flatter their own ego.

Recently, I have been using a method inspired by "Blink", the book written by Malcolm Gladwell of "Tipping Point" fame, which involves chatting to the person in a general way and then after 15 minutes going with your gut feeling. This actually worked surprisingly well (and I felt really good as I had gained 45 minutes from the process!). I know it worked well by comparing notes with a couple of other people who were using more orthodox techniques....

I will write up my thoughts on the Gladwell books another time, but for the moment I would like to confess that I actually like puzzles. However, I'd like to qualify that by saying that I don't think they are appropriate for interviews unless they are frighteningly hard and you get the interviewee to verbalise their approach to the problem.

Here are some mathematical puzzles in "gradually" increasing level of difficulty:
  • there are three submarines and a ship. Each submarine fires a torpedo at the ship, and each has a 30% chance of hitting it. What is the probability that the ship is hit ?
  • you are given many matches and two pieces of string that take one hour to burn but do not burn at a uniform rate - how do you time 45 minutes ?
  • differentiate x to the power x with respect to x
  • make a wireframe cube from eight one ohm resistors - what is the resistance between diagonally opposite corners ?
  • repeat 10 times: toss a coin - if heads put a white marble in an urn otherwise a black marble. Someone who knows the population process then selects a marble at random from the urn, examines it, and then returns it. They do this 10 times. If all the drawn marbles were white what is the probability that the urn only contained white marbles ?
Actually I have an additional confession: an interviewer once asked me the burning string question. Not liking these questions in interviews I replied that I would attempt it if they attempted the wireframe cube one for me (thinking it only fair that I get to evaluate their abstract problem solving ability if they are looking to do the same to me)......the interview didn't last very long :-)

After getting through this long post you need some light entertainment. What about the screen tests for the roles in star wars (you will need to hit play twice, about 5 seconds apart - but this was better than the autostart it would do otherwise) ?

Sunday, February 19, 2006

The Law

If you are thinking about going to Australia then you should have a think about whether to take your iPod or not. You could get arrested!

Voluntarily giving up privacy is very very very scary to me. If they ask me for a sample I will tell them where to go and I will likely be thought a criminal for doing so - be afraid, be very afraid!

Although I might not have anything to hide, what happens when the database that contains all this information is compromised and someone alters the results from some forensic DNA test to have the same electronic signature as mine ?- Afterall, they will probably outsource the maintenance of it to some company that has similiar employees to this one.

What happens when some insurance company gets hold of this information and starts to increase my premiums because of my genetic vulnerability to disease X that they just happened to find out about through some access to this database ? Actually, it is worse than it seems, because even if I can avoid inclusion in this database it is still possible that they could use it to identify me/my genetic susceptibilities. The UK also has some scary privacy developments.

On a lighter note, here is an interview on a deep and serious subject involving one of our greatest interviewers:

Tuesday, February 14, 2006

Birthday typing

Today was supposed to be my birthday. Today, many, many years ago was the day I was predicted to be born on by the doctor at the hospital. I wasn't born on this date though, so today is not my birthday. Hmmm, I think I'll still celebrate it though :-).

That aside, one of my goals for this year is to significantly improve my typing speed by developing touch typing skills. I tried some free typing tutors but quickly got bored of typing repetitive rubbish and so stopped using them. I realised I type enough rubbish everyday that I should really use that for my typing practice. From learn2type I found the following useful pictures which I now try and force myself to follow:

It is still quite awkward but it is definitely getting easier (before starting this exercise I was a 2-3 fingers each hand typist; 54wpm). Fingers (un?)crossed that I can make some significant improvement in a reasonable amount of time (100wpm is the initial goal - how long will it take?). Actually, I should also investigate keyboard ergonomics some...but that can be for another post.

Sunday, February 12, 2006

no TV means vids

Last week I switched off the TV. Last Sunday to be precise. Not only did I switch it off, but I also switched it off at the button on the front rather than just switching it off with the remote. Not only did I switch it off at the button, I also switched it off at the plug-board. I switched off the TV last Sunday, and I haven't switched it back on since!

As a result, I spent way more time on the computer, quite a lot of which was really productive. However, regular breaks when doing intense work are important and rather than vegging out in front of the TV, I did spend a little time doing some random searches.

I found out about the following video from AnDy and frankly I am somewhat blown away by the possibilities afforded by this way of human-computer interaction (I am sure there is a whole swath of new interaction patterns that will be enabled by new UI's like this). My vision of an executive desk now definitely incorporates one of these.

There has been a huge furor recently over religious blasphemy and freedom of speech. In the interest of furthering the debate I found "The Passion Reloaded":

Whether this is artistic license or intent to incite religious uproar, I know not.

I found three crazy (as in cheeseburger?) commercials:

  • The first for its originality.

  • The second for its humour:

  • The third for its crime deterrent phone (how long before the lawsuits come from copycat usage?).

This is a sweet assembly of some amazing soccer:

American college kids have too much time on there hands. That is the only explanation I can think of for trying this (don't worry, it isn't one of these drunken frat type things):

And finally, here is a humorous parody pop-video:

Tuesday, February 07, 2006


I came across PodioBooks today which is a pretty neat service. Basically once you've created a free account with them you can subcscribe to the podcasts of books you want to listen to (the selection is mainly sci-fi at the moment but type and number of books they are providing seems to be growing - everything is free so the authors/site are relying on donations (currently no adverts)). For each book you then get an RSS feed that you can put in your aggregator and PodioBooks will send you a chapter a time at an interval of your choosing (each book can have a different interval).

This actually works really nicely with netvibes (my preferred online RSS aggregator) which was a very pleasant surprise - I wasn't aware that there was an embedded mp3 player.

[Several things have caused me to question my use of time recently so I was looking for ways to make my dead-time more productive...]

Monday, February 06, 2006

snow retirement search

Went snowboarding again yesterday and the amount of snow falling was quiet something. The conditions on the whole were excellent though it was a bit of a shame that the place was so crowded. The amount of snow that has fallen here recently was brought to home by a one person in our group commenting that the restaurant that we just walked down hill to is normally (during ski-season!) at the top of a rather large staircase. Other people wondered what would happen to the local towns when all this snow/ice started to melt come spring - since it all doesn't melt at the same time I am not convinced that this is such a huge issue. Perhaps the streams will be high for longer, but will they also be significantly higher ?- I don't know!

A subject close to my heart that I've not yet managed to realise is early retirement. Here is an article that looks at the issue more completely than the "I just need to save this much money" over-simplification. I have plenty of things to spend my time on (actually I have too many things) but for the forseeable future (ok, so I can be a bit short-sighted) the "save this much money" issue is the biggest one on my plate. I have some ideas, one of which I was going to write about here, and then I wondered about all these search engines getting all those tentative queries that people submit when looking for a service that they don't know exists. If they mine their data properly they should see what gaps exist that have a waiting market...I wonder how many of these recent betas were inspired by the mining of search queries ? I wonder if the search engines will ever be asked to provide search logs to help with patent disputes, etc.

On a totally different note, this is a very serious round-a-bout in the UK. Next time I am there I am tempted to go there just for the experience (though my gut tells me that it is likely to be less exciting than it looks :-) ).

Here is another Aussie beer commercial (these are hilarious - there was another link to one in the same series in a previous post):

Saturday, February 04, 2006

Elephant vector

This news item about ageing and dead cells in the skin caught my attention the other day not least because it made me realise an obvious point that I had not hitherto considered: Namely that, survival of the fittest in the wild only really matters while you are still able to reproduce reliably (otherwise you are in an edge class - edge classes' effects on their species at large is probably the same or less than the effect due to random mutation).

I seem to remember reading somewhere (though I think that might be an illusion) something that I'll paraphrase as "at the end of the day, an elephant is simply a vector to propagate elephant genes." This of course should be rephrased as to only apply to those elephants still able to reproduce thus relegating elephants no longer able to reproduce to being merely empty vectors.

[A couple of beers later....]

If the reason for reproductive shutdown is caused by some different biological timer than the standard ageing process (does ageing have a single biological timer, or is it simply the cummulative result of multiple timer expirations ?) then perhaps one approach to attacking the ageing issue is to adjust the selective pressures on a sufficiently short-lived organism (i.e. extend the reproductivity of the creature and ensure that age has no negative influence on mate selection) and let evolution solve the issue (this assumes of course that the reproductive shutdown in organisms (NB I don't know for sure that this is generally true) itself wasn't the result of nature having already tried this and found it to do more harm than good)....

With the freezing of gametes for later use, the imminent advent of human cloning, and the richest people getting the best medical care I wonder how long our distant successors will live for naturally ? Of course, all successful approaches are valid, as this is what evolution itself enforces.

By the way, on a completely different note, anyone wondering how much Google's search results differ between the .com and .cn domains should try this (the default query is "tiananmen"; but you can compare anything you wish).