Wednesday, October 24, 2012

Progress. Whoa..

It's been a bit of a hiatus, but I've been at it the whole time.  I'm finally starting to feel comfortable writing code.  That sounds a bit silly when I say it out loud; I've been reading and writing code on a daily basis for several weeks now.  And yet, I never felt a sense of mastery over the concept I was trying to model, or the solution I was trying to implement.  I've been unable to craft 100% exactly what I want into a set of precise instructions, though I've caught a glimpse of what that feels like here and there.

So there's this set of math-oriented programming challenges on the interwebs, called Project Euler.  I'm (slowly) completing them, one-by-one.  A maths wizard I am not, by any means, and I constantly feel like I'm in over my head when working some of these problems.  They get progressively harder in succession, and with every one of these I knock down, inevitable fist pumping ensues.

Here's problem #5:
2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.  What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?
Now the cool thing about Euler problems is they are open-ended in their implementation.  You can use any language, any model, and any algorithm, so long as you reach the correct solution.  I really like this method of learning, as opposed to a problem set like pyschools. Pyschools does a lot of hand-holding in helping frame the problem and shape your program.  Euler does not care about how you solve the problem in the slightest, and I think being 'stranded' in this way forces you to pull up your bootstraps and design your solution from the ground-up.  I think us beginner programmers face an uneasiness once we step out of Tutorial Land and into Outer Problem Space.  The only way to overcome this obstacle is to grab the nearest handhold and start climbing.

Anyway, I haven't yet reached a solution for this one, but I'm close.  Thus far, I've been able to write a small program to tackle the smaller problem: producing the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.  This gives me the ability to test a small-scale solution before I blow it up for the actual problem (all digits 1-20).

divisors = [2,3,4,5,6,7,8,9,10]

def euler_5(*divs):
    start = divs[0]
    for d in range(1, len(divs) + 1):
        start *= d
    g = 0
    for n in range(start, 0, -divs[0]):
        g += 1
        check = 0
        for d in divs:
            check += n % d
        if check == 0:
            ans = n
    print ans, g


In the first part, I'm trying to determine a starting number to begin testing for divisibility.  I ended up multiplying all the numbers in the range of divisors and counting down from there.  Why?  I wanted to begin with a number that I knew already had to be divisible by all the members of the divisor set.... plus that was just the first method I could think of.   This part could really use some work, generating a better guess is essential to having a fast iterative algorithm.

The second loop increments my guess counter, g, and then in a nested loop iterates through each element d in divisors, checking to see if they divide evenly.  This is accomplished through the modulus operator (%), which instead of returning the result of a division, returns the remainder only.  If a number passes all checks, I then store it in the variable ans, continuing on to see if I can find a smaller number.

I've been able to get it to spit out the number 2520 given a divisor list of the numbers 1 through 10, so I know it works.  My current problem is when I try divisors from 11 to 20 my initial guess is too high.  IDLE is giving me an error, I think the Python list object is unable to hold a range of numbers 670,442,572,800 digits long, and I wouldn't expect it to.  That's quite big.

So I've gotta figure a workaround for that, but confidence abounds!  Happy coding.

Thursday, October 11, 2012


Trying to get the basic shell of my poke_clone working, not coming along as easy as I expected.  In the process of trying to get it up on git so I can spam r/learnpython questions about my source, I found this little intro tut on how Git actually works as a VCS: Getting-Started-Git-Basics.

Tuesday, October 9, 2012

Scratchlist #1

So this is my scratchlist, which is a bunch of mental throw-up about stuff I'm working on, learning, and stuff I'm planning on learning next. Might as well write it down and keep track.

project: search engine
In the process of launching learning how to launch my basic search engine from Udacity CS101.  Need to work on receiving and handling queries via forms and familiarize with Google AppEngine's framework.  I do see a problem: I don't really know what I should use for my search corpus.  Ideally, this would be some set of pages whose links eventually terminate, but I can't have my web crawler crawling an infinite # of links.  I think I will have to implement some sort of 'depth-limiter' into the crawler to establish a stopping point for link-indexing.  How?  I don't know.

project: text-based Pokemon game clone
Main objective is practicing OOP-basics in Python.  Perhaps this can also be a good app to experiment on later when I learn some socket-handling and want to make it into a multiplayer game.  That'd really be cool, but I'll have to put that one on the back-burner right now.

project: blog platform
Developing in tandem with CS253 Web Applications class from  This is a great project to learn database interaction with.  I mean, a blog post is essentially a string of text, stored in a table somewhere, should be easy as pie, right? WRONG.

setting up my new domain!
I took the plunge and shelled out for my own domain. Probably a bit premature, but for now at least I have my own little playground.

the Command Line
I feel like science dog when I open terminal.  Forcing myself to do accomplish as much as I know how to do with a CLI instead of gui's... the main reason for this is so many tutorial and educational resources out there basically expect such knowledge, and I don't feel comfortable just entering sudo commands without knowing what effect they'll have.

This is another thing I want to learn in order to better understand what I'm learning (huh? paradox).  Lately I've come across a couple treasure troves of knowledge, all taught in java, which is a strictly-typed language unlike Python, which is dynamically-typed.

check out TheCherno's awesome gamedev tutorial series:

Tuesday, October 2, 2012


I don't understand Github. 

edit: I sort of understand Github.