# 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

# 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.