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!

Advent of Code: Day 25

2015-12-25

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Part 1: Take the relation:

F(n) = \left\{\begin{matrix} 20151225 & \textrm{if}\ n = 1 \\ 252533F(n-1) \mod 33554393 & \textrm{otherwise} \end{matrix}\right.

Arrange the values according to Cantor's diagonal argument. Find the value at a specific cell.

Advent of Code: Day 24

2015-12-24

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Part 1: Split a list of integers into three groups of equal sum. Find the grouping such that the smallest group has the least items, breaking ties by the smallest product for that group.

Advent of Code: Day 23

2015-12-23

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Part 1: Create a simple virtual machine with two registers (a and b, non-negative integers) and six instructions:

hlf (a|b) - divide the given register by half, round down
tpl (a|b) - triple the given register
inc (a|b) - add 1 to the given register
jmp [+-]\d+ - jump forward/backwards by the given number of instructions
jie (a|b), [+-]\d+ - if the given register is even, jump
jio (a|b), [+-]\d+ - if the given register equals one, jump

Advent of Code: Day 22

2015-12-22

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Part 1: Simulate an RPG mage battle; finding the winning solution using the least mana. See the original writeup for more details.

Advent of Code: Day 21

2015-12-21

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Part 1: Given a shop full of weapons (buy exactly one), armor (buy zero or one), and rings (buy 0, 1, or 2), determine the set of items that will defeat a given enemy for the minimum cost (see the original writeup for more details).

Advent of Code: Day 20

2015-12-20

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Part 1: P(n) is defined such that for each number i, add 10i to any number divisible by i. Find the first value n such that P(n) is at least a given target number.

Advent of Code: Day 19

2015-12-19

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Part 1: Given a list of list of string replacements and an input string, determine how many unique output strings are possible after one step.

Advent of Code: Day 18

2015-12-18

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Part 1: Simulate Conway's Game of Life. Count how many lights are on after 100 iterations.

Advent of Code: Day 17

2015-12-17

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Part 1: Given a list of containers of varying sizes and a total volume to contain, determine how many different combinations of containers match exactly the given volume.

Advent of Code: Day 16

2015-12-16

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Part 1: Given a list of target values of the form:

children: 3
cats: 7
samoyeds: 2

And a list of ‘Aunt Sues’, each with known values:

Sue 1: children: 1, cars: 8, vizslas: 7
Sue 2: akitas: 10, perfumes: 10, children: 5
Sue 3: cars: 5, pomeranians: 4, vizslas: 1

Determine which Sue has no unset but matching values.

For example, Sue 1 is invalid because children is 1 versus 3 and Sue 2 because children is 5 versus 3. Given only the values above, Sue 3 would be valid since there are no contradictions.