The earliest memory I have of ‘programming’ is in the early/mid 90s when my father brought home a computer from work. We could play games on it … so of course I took the spreadsheet program he used (LOTUS 123, did I date myself with that?) and tried to modify it to print out a helpful message for him. It … halfway worked? At least I could undo it so he could get back to work…

After that, I picked up programming for real in QBASIC (I still have a few of those programs lying around), got my own (junky) Linux desktop from my cousin, tried to learn VBasic (without a Windows machine), and eventually made it to high school… In college, I studied computer science and mathematics, mostly programming in Java/.NET, although with a bit of everything in the mix. A few of my oldest programming posts on this blog are from that time.

After that, on to grad school! Originally, I was going to study computational linguistics, but that fell through. Then programming languages (the school’s specialty). And finally I ended up studying censorship and computer security… before taking a hard turn into the private sector to follow my PhD advisor.

Since then, I’ve worked in the computer security space at a couple of different companies. Some don’t exist any more, some you’ve probably heard of. I still program for fun too, and not just in security.

But really, I still have a habit of doing a little bit of everything. Whatever seems interesting at the time!

Command line user agent parsing

2014-02-07

Quite often when working with internet data, you will find yourself wanting to figure out what sort of device users are using to access your content. Luckily, if you’re using HTTP, there is a standard for that: The user-agent header.

Since I’m in exactly that position, I’ve added a new script to my Dotfiles that reads user agents on stdin, parses them, and writes them back out in a given format.

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Combining sort and uniq

2014-02-07

A fairly common set of command line tools (at least for me) is to combine sort and uniq to get a count of unique items in a list of unsorted data. Something like this:

$ find . -type 'f' | rev | cut -d "." -f "1" | rev | sort | uniq -c | sort -nr | head

2649 htm
1458 png
 993 cache
 612 jpg
 135 css
 102 zip
  99 svg
  60 gif
  45 js
  27 pdf

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Factoring factorials

2014-01-27

There was a new post on Programming Praxis a few days ago that seemed pretty neat:

Given a positive integer n, compute the prime factorization, including multiplicities, of n! = 1 · 2 · … · n. You should be able to handle very large n, which means that you should not compute the factorial before computing the factors, as the intermediate result will be extremely large.

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Graph coloring

2014-01-15

Here’s another one from /r/dailyprogrammer:

… Your goal is to color a map of these regions with two requirements: 1) make sure that each adjacent department do not share a color, so you can clearly distinguish each department, and 2) minimize these numbers of colors.

Essentially, graph coloring.

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Graph radius

2014-01-14

Here’s a quick problem from the DailyProgrammer subreddit. Basically, we want to calculate the radius of a graph:

radius(g) = \min\limits_{n_0 \in g} \max\limits_{n_1 \in g} d_g(n_0, n_1)

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