shiv.me

Phew! What an awesome 23 hours! I’m just back from Barcamp Vancouver 2010 #bcv10. (Check out some pictures from the event). It’s been a while, since I have been this tired and excited at the same time. There are a thousand threads competing for the processor(s) in my head right now. I met a lot of very interesting people, and learnt about some great ideas. It has been a very educational weekend, in general. For all the great folks I met, I’m sure there were many more that I couldn’t chat with. To you, I say, “Let’s meet on the internets“.

A few great projects/ideas:

• Arduino - Open hardware platform for very building very cool things. A very inexpensive way to build your very own robot army.
• Plumtree Portfolios - Vancouver-based wedding photographer platform. This wasn’t a talk, but I wish it had been. A very interesting, clean product. Shawn Taylor is the founder, and he is getting geared up. This is has the potential to be huge, especially in Vancouver.
• HTML5 - a great talk by John Baxall, CEO @ Mobify. One of the best talks, and a great intro into the world of feature detection on browsers.
• OpenRestaurants - a vision to make restaurant websites suck less. Fingers crossed that this will happen sooner. We can all use better access to data (and not keep it behind walls .. I’m looking at you Facebook)
• FashionQuest - Text-only adventure game engine. Aahh this brought back some memories. A very interesting use of YAML (In my world, it’s used as modelling language for NETCONF)
• Freaking Eyes EyePong- Control an ipad app with your eyes (This stuff just blew my mind. Playing pong with just your eyes is incredible, not to mention the zillion possibilities)
• Symphony CMS - an XSLT based open source wiki. Another hallway demo. If you work for a large company, and your current CMS sucks, give this a looksie.

Some people that I got a chance to chat with. Friend ‘em up on twitter. Check out their projects/websites. It will widen your world, and will make you think.

• Stephen Bau: website,  @bauhouse,
• John Boxall: website, @johnboxall
• Shawn Taylor: website, @stphotos
• Reilly ‘thejerk’ Lievers: website, @thejerk
• Cam Cavers: website, @camcavers
• Mike Cantelon: website, @mcantelon
• Craig Hennessey: personal, company
• Robin H. Johnson: website, @robbat2

Lastly, thanks to everyone who helped put up an wonderful event (and make my first one an incredible experience)

@RobertShaer, @AGladders, @NickMolnar, @DDrucker, @KK & @MattFriesen

The one thing I missed out on is meeting more designers. If you are in Vancouver, and want to meet for a chat on designing interfaces (which I suck at, with a vengeance), give me a shout @shiva.

Update: Found the video for eyePong.

The incredible cool hackers behind this are

Jon Chui, Tom Schultz and Craig Hennessey (founder of mirametrix).

Jon Chui has written about his experience in hacking eyePong. Check it out.

It’s been a while since I’ve done anything except write code — lots of it. The last 20 days have been insane, and ofcourse to a take a break from writing code, I like to read code that others write. (You DO know that I’m crazy, right?!). In one of my futile attempts at clearing my google-reader reading list, I chanced upon a post by Veerabahu, on finding if a number is a power of 2 (or not).

As he writes, there is the simpleton O(n) solution (you will have to click-through for that), and the most elegant (yet) bitwise solution:

/*
 */
bool
is_power_of_2(int n) {
   return ((n & -n) == n);
}

The bitwise way to calculate the power of 2 is probably the most efficient in c like languages. Ofcourse for that, your language of choice needs to support it and should be more efficient that common math functions. The other way is to use some simple math.

Let’s say N, is the value, and you need to check if it is a power of two. Compute n = log N / log 2. If floor(n) == n, then N was a power of 2.

/*
 */
bool
is_power_of_2_pure_math_baby(int n) {
    /* address -ve numbers */
    if (n < 0)
        n = -n;

    double i = log(n)/log(2);      /* i = power of 2 */
    return (lower(i) == i);        /* check if perfect power of 2 */
}

This is obviously, a less efficient way of checking if a number is a power of 2, than using the bitwise method. However, it has a few advantages:

1. It works exactly the same way for all values of n.
2. It works exactly the same way for all integers (ie, n can be int8/16/32/64, long, signed or unsigned, and the same logic would work
3. It is O(1) like the bitwise solution
4. It is less cryptic (ie just basic understanding of math is reqd for grokking this solution)
5. Finally, it can be extended in future to calculate if n is a power of *any value*, not just 2

Of course, the point Josh Bloch was making in interviewing engineers, was that he is interested in knowing the WHY of a solution. It does not matter if the algorithm is marginally less optimal or different. If you are an interviewer in your organisation, and you catch yourself asking a question like this, remember that if an engineer can reduce O(n) to O(1), stop with similar micro-skills test. Find out why she coded it the way she did. It will tell you a lot more about her skills than some algorithms/tricks that can be picked up in a couple a days, if not overnight.