The Zebra Puzzle is a famous logic puzzle in which there are five houses, each painted a different color. The houses have different inhabitants, who have different nationalities, own different pets, drink different beverages and enjoy different hobbies.
To help you solve the puzzle, you're given 15 statements describing the solution. However, only by combining the information in all statements will you be able to find the solution to the puzzle.
The Zebra Puzzle is a Constraint satisfaction problem (CSP). In such a problem, you have a set of possible values and a set of constraints that limit which values are valid. Another well-known CSP is Sudoku.
Your task is to solve the Zebra Puzzle to find the answer to these two questions:
The following 15 statements are all known to be true:
Additionally, each of the five houses is painted a different color, and their inhabitants are of different national extractions, own different pets, drink different beverages and engage in different hobbies.
There are 24 billion (5!⁵ = 24,883,200,000) possible solutions, so try ruling out as many solutions as possible.
Sign up to Exercism to learn and master Prolog with 108 exercises, and real human mentoring, all for free.
Explore 8 different ways of finding the Zebra Puzzle solution from 24 billion possible solutions, including ignoring invalid permutations as soon as possible, the AC-3 algorithm, a very succinct logic-based solution and even a genetic algorithm!