Powers of three

here's an obfuscated way to get powers of 3 from multiplying 1 by 2 and powers of two and two arrays (with a little addition in the mix). $a is what power of three to calculate.

$a=24;@a=(1);sub d{push@a,map{2*$_}@a};
d for('1'.."$a");$b=$#a;$_=0;
push@b,$_+=$a[$#a-$b--] until($b==-1);
print$b[2**$a-1];
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a simple note, it'll use 2*(2**$a) array elements, and is probably O(2**n) in memory usage and cpu time, so its probably one of the more ineffecient ways to calculate powers of three in existence

Comment on Powers of three Download Code

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Re: Powers of three by zshzn (Hermit) on Feb 07, 2006 at 02:35 UTC
Neat! I wouldn't interpolate $a in the for loop. Or 1. Makes me kind of wonder what influenced you to do so.	[reply]
Re^2: Powers of three by simcop2387 (Acolyte) on Feb 07, 2006 at 07:55 UTC
honestly i don't remember it was written in my statistics class at 9am i'm also partially curious as to why the program works, i know what its doing, i worked it out by hand before writing it in perl <Reveal this spoiler or all in this thread>	[reply]
Re^3: Powers of three by truedfx (Monk) on Feb 07, 2006 at 18:04 UTC
A simple explanation of why it works, since you wondered: <Reveal this spoiler or all in this thread> It's not proof, but hopefully it's good enough.	[reply]
Re^3: Powers of three by tweetiepooh (Hermit) on Feb 10, 2006 at 11:09 UTC
Nice code. Logically the state of any point is an XOR of its two parents taking a missing parent to be 0. (and seeding with a 1 at the point)	[reply]