Problem 780. Give a matrix that matches itself when rotated

Created by Ned Gulley
Appears in Cody Challenge

Difficulty:Rate

Solve Later
Add To GroupÃ‚

Given n and s, return a n-by-n matrix a of integers such that

 sum(sum(a == rot90(a)))

is equal to exactly s. The integers should be chosen from the set 1 to n.

So for instance, if n is 2, and s is 2, you could return

 a = [ 1 1 
       2 2 ]

since rot90(a) matches a in exactly one place.

For any n and s, a is of course not unique. I'm only checking to make sure the conditions are true.

Solve

Solution Stats

42 Solutions
13 Solvers

Last Solution submitted on Feb 04, 2025

Last 200 Solutions

Problem Comments

5 Comments

5 Comments

Show 2 older comments

Richard Zapor on 16 Nov 2012

s=feval(@evalin,'caller','s');

Lack of s input solved

Ned Gulley on 16 Nov 2012

Sorry guys. Sloppy problem creation on my part. Unfortunately my signature change will invalidate all the solutions up to this point, but yes it should be match_rot(n,s)

David Verrelli on 1 Dec 2017

"since rot90(a) matches a in exactly _two_ places" for the example in the problem statement?

Solution Comments

Show comments

Problem Recent Solvers13

Problem Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Problem 780. Give a matrix that matches itself when rotated

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers13

Suggested Problems

More from this Author50

Problem Tags

Community Treasure Hunt

Problem 780. Give a matrix that matches itself when rotated

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers13

Suggested Problems

More from this Author50

Problem Tags

Community Treasure Hunt

Players