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!

AoC 2021 Day 23: Amphipodinator

2021-12-23

Source: Amphipod

Part 1: Given 4 rooms full of amphipods with various energy costs for movement (a=1, b=10, c=100, d=1000) and a hallway, how much energy does it take (at minimum) to sort the amphipods into their own rooms with the following conditions:

AoC 2021 Day 22: Cubinator

2021-12-22

Source: Reactor Reboot

Part 1: Given a series of 3D cubes that either turn ON all or turn OFF all points in their region, calculate how many points in the region (-50..50,-50..50,-50..50) are ON at the end.

AoC 2021 Day 21: Dicinator

2021-12-21

Source: Dirac Dice

Part 1: Play a simple game (describe below) with a loaded D100 (that always rolls 1, 2, 3, … 99, 100, 1, …). Return the score of the losing player times the number of times the die was rolled.

AoC 2021 Day 20: Enhancinator

2021-12-20

Source: Trench Map

Part 1: Given a 9->1 cellular automota update function (take the pixel and 8 surrounding pixels as a 9-bit index into the function) and a binary image, apply the function twice and count the number of ’lit’ pixels. Assume that the canvas is infinite.

AoC 2021 Day 19: Point Matchinator

2021-12-19

Source: Snailfish

Part 1: You will be given a series of Scanners, each of which will tell you the location (from their point of view) of a series of Beacons. Each Scanner may be flipped or rotated in increments of 90 degrees in any direction. Determine where each Scanner and Beacon is by overlaying the maps (with at least pairwise 12 matches).

AoC 2021 Day 18: Pairs of Pairs

2021-12-18

Source: Snailfish

Part 1: Given the following definition of Snailfish numbers, add a series of Snailfish numbers and return the magnitude of the result.

AoC 2021 Day 17: Pew-Pewinator

2021-12-17

Source: Trick Shot

Part 1: Simulate a projectile with an integer initial velocity (x, y), air resistance that tries to reduce x-velocity to 0, and gravity that increases y-velocity by 1 each time. Given a target range, find the highest point reached by a projectile that ends a tick (not one that crosses over) within the target area.

AoC 2021 Day 16: Depacketinator

2021-12-16

Source: Packet Decoder

Part 1: Given a recursive binary packet definition (see below), parse the given packet. Return the sum of each packet’s `version`.

AoC 2021 Day 15: Low Ceiling Simulator

2021-12-15

Source: Chiton

Part 1: Given a grid of weights, find the minimum path from top left to top right. Return the total weight along that path.

AoC 2021 Day 14: Polymerizationinator

2021-12-14

Source: Extended Polymerization

Part 1: Given a complete function `f(a, b) -> c` where any string `ab` becomes `acb` and an input string, apply the function at the same time to every (overlapping) pair of letters. Repeat this time times. Report the difference in counts between the most and least common letters in the final situation.

Source: Amphipod

Part 1: Given 4 rooms full of amphipods with various energy costs for movement (a=1, b=10, c=100, d=1000) and a hallway, how much energy does it take (at minimum) to sort the amphipods into their own rooms with the following conditions:

Source: Reactor Reboot

Part 1: Given a series of 3D cubes that either turn ON all or turn OFF all points in their region, calculate how many points in the region (-50..50,-50..50,-50..50) are ON at the end.

Source: Dirac Dice

Part 1: Play a simple game (describe below) with a loaded D100 (that always rolls 1, 2, 3, … 99, 100, 1, …). Return the score of the losing player times the number of times the die was rolled.

Source: Trench Map

Part 1: Given a 9->1 cellular automota update function (take the pixel and 8 surrounding pixels as a 9-bit index into the function) and a binary image, apply the function twice and count the number of ’lit’ pixels. Assume that the canvas is infinite.

Source: Snailfish

Source: Snailfish

Part 1: Given the following definition of Snailfish numbers, add a series of Snailfish numbers and return the magnitude of the result.

Source: Trick Shot

Source: Packet Decoder

Part 1: Given a recursive binary packet definition (see below), parse the given packet. Return the sum of each packet’s version.

Source: Chiton

Part 1: Given a grid of weights, find the minimum path from top left to top right. Return the total weight along that path.

Source: Extended Polymerization

Part 1: Given a complete function f(a, b) -> c where any string ab becomes acb and an input string, apply the function at the same time to every (overlapping) pair of letters. Repeat this time times. Report the difference in counts between the most and least common letters in the final situation.

Part 1: Given a recursive binary packet definition (see below), parse the given packet. Return the sum of each packet’s `version`.