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. That’s about where I am today!

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

Chopping words

2012-10-15

One more challenge from Programming Praxis’ Word Games today (there are only a few left!). This time we have the challenge of cutting off bits of words, one letter at a time, such that each step is still a word.

The example given in their post is planet → plane → plan → pan → an → a, although surely many such examples exist.

Dodgson’s Doublets

2012-10-14

Today we have doublets source code, dictionary source code, queue source code. Using the same source code as the previous two posts (here and here, described originally here) for the dictionary, the code is a pretty straight forward case of using recursion to do backtracking. Basically, try all of the possible next words one letter different. Whenever you find a dead end, back up and try a different path. Something like this:

Word cubes

2012-10-13

Continuing in my recent set of word-cube source code. Like yesterday, it’s designed to work in Racket 5.3+.

Squaring the Bishop

2012-10-11

Okay, this one was just neat. Based on word-squares source. I’ve only tested it in Racket 5.3+, but newer versions should work as well. Racket 5.2 won’t work without some tweaking as (at the very least) it’s missing a definition for string-trim.

Dictionary tries in Racket

2012-10-11

For the next few posts, we’re going to need a way to represent a dictionary. You could go with just a flat list containing all of the words in the dictionary, but the runtime doesn’t seem optimal. Instead, we want a data structure that lets you easily get all possible words that start with a given prefix. We want a trie.

. Source: dictionary source code

Two Word Games

2012-10-10

Another day, another post from Programming Praxis. Today they posted a word game that seems simple enough: first find all words in a given dictionary that contain all five vowels (a, e, i, o, u) in ascending order and then find any words (at least six letters long) where the letters are all in ascending alphabetical order.

Evaluating prefix/infix/postfix expressions

2012-10-08

In yesterday’s post, I talked about three different ways to write expressions: prefix, infix, and postfix expressions. I also promised to write up a web-based example that would show the guts of each algorithm in action. Well, here it is! Use the three buttons at the top to switch between the different machines. Enter an expression in the box and click run to evaluate it. The only things that are supported at the moment are numbers (integers or floating point) and the operators +, -, *, and /, although the code is extensible enough that adding more shouldn’t be an issue.

Three ways to write expressions

2012-10-07

(- (- (+ 4 (* 2 7)) (* (- 1 6) 5)) 1)

is the same as

4 + 2 * 7 - (1 - 6) * 5 - 1

is the same as

4 2 7 * + 1 6 - 5 * - 1 -

Madness right?

Generated HTML index

2012-10-06

A simple script today to generate an HTML index listing all of the files in a given directory. This has come in handy in the past when Apache has had Options -Indexes set (disabling their automatically generated indexes) and I didn’t have the permissions to override it.

Querying CSV files with SQL

2012-10-04

Some time ago, I had a bunch of CSV files that I needed to extract some data from. They were all organized into tables with related columns between them all that made me think of a relational database–and it’s really easy to query relational databases, just use SQL. So what did I do? I wrote a script that will let me query CSV files as if they were a relational database.