Anaconda Python/R: free disk space by removing old packages

This post highlights how to quickly clean old packages from anaconda, the scientific Python/R distribution.

Hidoku Solver in Python: branch cutting, intelligent successor generation and some simplifications

In this post we are implementing a Hidoku solver (Hidoku is yet another fine number puzzle) that uses a depth first search, branch cutting, limited (intelligent) successor generation and some automatic simplification. Usually, a Hidoku is a quadratic board consisting of n x n fields - but rectangular or other forms would be possible as well. With each Hidoku, some fields are already pre-filled with numbers at the beginning. The game goal is to fill in all other numbers so that an ascending number queue is built: each number has to be adjacent to it's successor, with adjacent meaning in an adjacent horizontal, vertical or diagonal field.

Cracking RC4 messages that use weak RC4 reinitialization for each message part

This post deals with a short excerpt of a security and hacking related exercise at the University of Applied Sciences Upper Austria, Campus Hagenberg: we obtain the plaintext from an intercepted RC4 encoded message, from which we know that it uses an easy to crack re-initialization of the RC4 cipher for each message part.

Draught board puzzle / checkerboard puzzle solver in Python

The checkerboard puzzle or draught board puzzle (also called Krazee Checkerboard Puzzle, Banzee Island checkerboard puzzle, Zebas puzzle, etc.) is a mutilated chessboard problem, which further is a tiling puzzle/dissection puzzle. Hence, the core problem is similar to the one of solving the well known Tangram, which some of you might be familiar with. The … Continue reading Draught board puzzle / checkerboard puzzle solver in Python →

Magic number board puzzle solver in Python

The magic number board puzzle is yet another equation puzzle (similar to the first equation puzzle or Jodici) - but has a notable larger solution space. The magic number board is a quadratic board, consisting of 5x5 = 25 fields, which are organized as 5 horizontal rows and 5 vertical columns. Each field should contain … Continue reading Magic number board puzzle solver in Python →

Jodici solver: Python vs Prolog

Jodici is a fun and intuitive number placement puzzle. It consists of a circle which a) contains 3 nested rings and b) is divided into 6 cake-piece-like sectors. As with Sudoku, the goal is to fill in all numbers, while satisfying certain rules: each field must contain an integer [1,9], with each such integer being used twice in total. Further, each sector sums up to 15 and each ring to 30.

Flower disk rotation puzzle solver: Python vs Prolog

The flower disk rotation puzzle consists of 4 wooden, stacked disks. The disks are connected at their center via a pole, so that they can be rotated. Each disk contains holes that are arranged around the disk center in the form of a flower. The holes are uniformly spread, so that there is space for 12 holes - but each disk only has 9 of these 12 possible holes (the position of holes differ per disk). The remaining 3 areas are instead made of solid wood. The goal is to rotate the disks so that all holes are covered by at least one of the disks (as we have a total amount of 4*3=12 solid areas for a total of 12 holes, each solid area must cover exactly one hole).

Equation puzzle solver: Python vs Prolog

Our equation puzzle consists of 3 horizontal and 3 vertical equations. Each equation adds/multiplies 3 numbers between -9 and 99 to a single result number. The goal is to find all numbers for the still unset variables.

convertconditional: convert an image if it fulfills certain conditions

Recently I needed a script to batch convert only those images amongst a large amount of images which fulfil certain criteria, namely of being exactly of a stated size. The script is based on ImageMagick's convert and basically takes an arbitrary amount of convert parameters. I personally use this script to automatically reduce size and … Continue reading convertconditional: convert an image if it fulfills certain conditions →

“Pick Stones” Game – an Artificial Intelligence Toy Problem

What's the "Pick Stones" Game? The "Pick Stones-" or "Nim Game", or more exactly the "Marienbad Game" can be seen as an AI toy problem, that students at the Departments of Software Engineering and Medicine- and Bioinformatics at the University of Applied Sciences Upper Austria have to solve in the second semester. The game rules … Continue reading “Pick Stones” Game – an Artificial Intelligence Toy Problem →