Problem 306. Eight Queens Solution Checker

Created by Steve Eddins
Appears in Computational Geometry II

Difficulty:Rate

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Write a function to verify whether an arrangement of queens on a chessboard is a valid solution to the classic eight queens problem.
In the eight queens problem, eight queens must be placed on a chessboard such that no two queens attack each other. That is, no two queens can share the same row, column, or diagonal. The diagram below is one possible solution:
Your function should take an 8-by-8 matrix of 0s and 1s, where the 1s represent the position of the queens, and return a logical 1 if the solution is valid or a logical 0 otherwise.
EXAMPLE 1
   in1 = [ ...
       0 0 0 1 0 0 0 0
       0 0 0 0 0 0 1 0
       0 0 1 0 0 0 0 0
       0 0 0 0 0 0 0 1
       0 1 0 0 0 0 0 0
       0 0 0 0 1 0 0 0
       1 0 0 0 0 0 0 0
       0 0 0 0 0 1 0 0 ];
   isEightQueensSolution(in1)
returns 1.
EXAMPLE 2
   in2 = [ ...
       0 0 0 1 0 0 0 0
       0 0 0 0 0 0 1 0
       0 0 1 0 0 0 0 0
       0 0 0 0 0 0 0 1
       0 1 0 0 0 0 0 0
       1 0 0 0 0 0 0 0
       0 0 0 0 1 0 0 0
       0 0 0 0 0 1 0 0 ];
   isEightQueensSolution(in2)
returns 0. (Notice that the queens on the bottom two rows share a diagonal.)

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Last Solution submitted on Jan 06, 2025

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2 Comments

@bmtran (Bryant Tran) on 11 Feb 2012

This question is kind of a duplicate of Ned's N-queens checker: http://www.mathworks.com/matlabcentral/cody/problems/113-n-queens-checker

Steve Eddins on 12 Feb 2012

Oops, I didn't know about that one!

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