https://github.com/reem/n-queens.js

A blazingly-fast, bit-shifting, backtracking, n-queens algorithm in javascript.
https://github.com/reem/n-queens.js

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A blazingly-fast, bit-shifting, backtracking, n-queens algorithm in javascript.

• Host: GitHub
• URL: https://github.com/reem/n-queens.js
• Owner: reem
• Created: 2014-04-25T04:15:23.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2014-04-25T04:28:23.000Z (over 10 years ago)
• Last Synced: 2024-05-05T05:32:38.264Z (5 months ago)
• Language: JavaScript
• Homepage:
• Size: 336 KB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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• awesome-blazingly-fast - n-queens.js - A blazingly-fast, bit-shifting, backtracking, n-queens algorithm in javascript. (JavaScript)

README

        
#Javascript N-Queens

The 30,000 foot overview:

Our inner helper function that does all of the work only takes a

few arguments: three integers which represent the spots on the

current row that are blocked by previous queens.

The "secret sauce" here is that we can avoid passing around the board

or even the locations of the previous queens and instead we use this

information to infer the conflicts for the next row.

Once we know the conflicts in our current row we can simply recurse

over all of the open spots and profit.

We can then use bit magic to significantly speed up the process over

arrays - almost a 50x speedup.

Time for n=12: `60`ms.

Please see `src/solvers.js` for a significantly more detailed explanation

of the algorithm including a thorough explanation of all bit magic.

This was part of the curriculum at Hack Reactor and worked on with a pair.