AoC 2016 Day 11: Radiation Avoider

2016-12-11

Source: Radioisotope Thermoelectric Generators

Part 1: Input will be a list of the following form:

The first floor contains a hydrogen-compatible microchip and a lithium-compatible microchip.
The second floor contains a hydrogen generator.
The third floor contains a lithium generator.
The fourth floor contains nothing relevant.

You have an elevator that can move exactly 1 or 2 items. You can only leave a microchip on a floor with a non-matching generator if a matching generator is also present.

Move all items to the top (4th) floor.

iOS Backups in Racket: Apps

2015-01-29

So far we’ve read backup files, parsed contacts, and parsed messages. Today we’re going to dig a little deeper and start parsing apps specifically.

iOS Backups in Racket: Messages

2015-01-27

So far we’ve laid the groundwork, loading local iOS backups and parsed out contacts. Today let’s take another step down the rabbit hole and figure out how messages are stored.

iOS Backups in Racket: Contacts

2015-01-23

After yesterday’s post laying the groundwork for looking into iOS Backups, today why don’t we actually start digging into one of the more interesting files: your list of contacts.

iOS Backups in Racket: Groundwork

2015-01-22

For the last little while, I’ve been spending my spare programming time working on a slightly larger project than I normally do: a Racket library for reading iOS backups.

Basically, I want to take the mess that is an iOS backup (not particularly designed to be easy to read by other programs) and extract some information from it, backing it up in a more easily readable format.

Specifically, I would like to be able to backup:

Contact information: Even thought they’re mostly from Facebook, it will be useful for the other parts
Messages: These are taking up a large portion of my phone’s hard drive, mostly due to attachments. Back them up just in case¹²
Photos: I’m already backing these up, but it would be nice to have it in the same process
Application data:
List of applications over time
Moves: GPS location
Downcast: List of current podcasts
Sleep Cycle: Sleep data
Boardgame Scorer: High scores for board games

Factor trees

2014-06-17

Another five minute challenge¹, this time from /r/dailyprogrammer: given any positive integer, create and render a factor tree.

Quadtree image compression

2014-05-28

About two weeks ago, I came across a post via /r/programming: Quadtree Art^(src). In a sentence, the goal is to recursively divide an image into a quadtree, at each step expanding the current node with the largest internal variance.

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.

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)

Edges to adjacency

2013-12-23

Another quick one, this time from /r/dailyprogrammer:

Your goal is to write a program that takes in a list of edge-node relationships, and print a directed adjacency matrix for it. Our convention will follow that rows point to columns. Follow the examples for clarification of this convention.