https://github.com/iwharris/queens-py

Python solution for the "n-queens puzzle".
https://github.com/iwharris/queens-py

Last synced: 1 day ago
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Python solution for the "n-queens puzzle".

• Host: GitHub
• URL: https://github.com/iwharris/queens-py
• Owner: iwharris
• Created: 2015-01-11T01:44:38.000Z (almost 10 years ago)
• Default Branch: master
• Last Pushed: 2015-01-11T01:44:42.000Z (almost 10 years ago)
• Last Synced: 2023-02-26T20:56:58.308Z (over 1 year ago)
• Language: Python
• Size: 97.7 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md

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README

        
## Queens ##

This is a quick and dirty solution to the "Eight queens puzzle." It finds all unique solutions to the puzzle, printing each solution as it is encountered.

From the [Wikipedia article](http://wikipedia.org/wiki/Eight_queens_puzzle):

> The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens threaten each other. Thus, a solution requires that no two queens share the same row, column, or diagonal. The eight queens puzzle is an example of the more general n-queens problem of placing n queens on an n×n chessboard, where solutions exist for all natural numbers n with the exception of n=2 or n=3.

This implementation can be used to solve the the general **n-queens problem**. You can adjust **n** by modifying the value of `N_QUEENS`.

It uses a recursive, kinda-bruteforce approach with backtracking. It is **by no means optimal**. For example, memory usage can be improved by using a single 64-bit integer and bit-shifting to represent the board state for **n queens** up to **n = 8**.