Problem 114. Check to see if a Sudoku Puzzle is Solved

Created by @bmtran (Bryant Tran)

Solve Later

{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","targetMode":"","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","targetMode":"","relationshipId":"rId2","target":"/matlab/output.xml"}],"parts":[{"partUri":"/matlab/document.xml","relationship":[],"contentType":"application/vnd.mathworks.matlab.code.document+xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:rPr><w:b/></w:rPr><w:t>Description:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Your task, should you choose to accept it, is to make a function that checks to see if a 9x9 matrix of integers represents a completed sudoku puzzle. For more information regarding sudokus, refer to the</w:t></w:r><w:r><w:t> </w:t></w:r><w:hyperlink w:docLocation=\"http://en.wikipedia.org/wiki/Sudoku\"><w:r><w:t>wikipedia page</w:t></w:r></w:hyperlink><w:r><w:t>.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>The function will return true only when it's a completed sudoku puzzle. A value of 0 refers to a blank entry.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:rPr><w:b/></w:rPr><w:t>Example:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ input = [ 8 2 4 9 5 3 6 7 1\n 6 3 5 8 1 7 9 2 4\n 7 1 9 6 2 4 8 5 3\n 5 8 7 2 9 1 3 4 6\n 1 4 2 7 3 6 5 8 9\n 3 9 6 4 8 5 2 1 7\n 2 6 1 5 4 9 7 3 8\n 4 7 8 3 6 2 1 9 5\n 9 5 3 1 7 8 4 6 2 ];\n answer = true;\n\n input = [ 8 2 4 9 5 3 6 7 1\n 6 3 5 8 1 7 9 2 4\n 7 1 9 0 2 4 8 5 3\n 5 8 7 2 9 1 3 4 6\n 1 4 2 7 3 0 5 8 9\n 3 9 6 4 8 5 2 1 7\n 2 6 1 5 4 9 7 3 8\n 4 7 8 3 6 2 1 9 5\n 9 5 3 1 7 8 4 6 2 ];\n answer = false;]]></w:t></w:r></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

Description:Your task, should you choose to accept it, is to make a function that checks to see if a 9x9 matrix of integers represents a completed sudoku puzzle. For more information regarding sudokus, refer to the <a href="http://en.wikipedia.org/wiki/Sudoku">wikipedia page</a>.The function will return true only when it's a completed sudoku puzzle. A value of 0 refers to a blank entry.Example:<pre> input = [ 8 2 4 9 5 3 6 7 1
 6 3 5 8 1 7 9 2 4
 7 1 9 6 2 4 8 5 3
 5 8 7 2 9 1 3 4 6
 1 4 2 7 3 6 5 8 9
 3 9 6 4 8 5 2 1 7
 2 6 1 5 4 9 7 3 8
 4 7 8 3 6 2 1 9 5
 9 5 3 1 7 8 4 6 2 ];
 answer = true;</pre><pre> input = [ 8 2 4 9 5 3 6 7 1
 6 3 5 8 1 7 9 2 4
 7 1 9 0 2 4 8 5 3
 5 8 7 2 9 1 3 4 6
 1 4 2 7 3 0 5 8 9
 3 9 6 4 8 5 2 1 7
 2 6 1 5 4 9 7 3 8
 4 7 8 3 6 2 1 9 5
 9 5 3 1 7 8 4 6 2 ];
 answer = false;</pre>

Solve

Solution Stats

1466 Solutions
279 Solvers

Last Solution submitted on Jan 18, 2021

Last 200 Solutions

Problem Comments

5 Comments

5 Comments

Show 2 older comments

@bmtran (Bryant Tran) on 28 Jan 2012

Seems like my test suite wasn't robust enough, so I've bolstered it with some trickier situations

yurenchu on 26 May 2017

You should have added a test case with 5*ones(9) as a test matrix.

Asif Newaz on 13 Nov 2019

ur test suite 6 is wrong, isn't it??

Dyuman Joshi on 26 Dec 2020

@bmtran can you explain why test case #6 (toeplitz variation) is false?

@bmtran (Bryant Tran) on 26 Dec 2020

In addition to each row and column needing to have 1 through 9, each 3x3 sub-region must have 1 through 9 as well.

Solution Comments

Solution 569156

1 Comment

1 Comment

Chellammai C on 29 Jan 2015

the solution is stating false for S=toeplitz([1 9:-1:2],1:9); but it is true. hence solution failed

Solution 210174

2 Comments

2 Comments

danteliujie on 12 Apr 2019

god!

Nico Noordam on 8 Jan 2020

This solution fails on
input = [ 8 2 4 9 5 3 6 7 1
6 3 5 8 1 9 7 2 4
7 1 9 6 2 4 8 5 3
5 8 7 2 9 1 3 4 6
1 4 2 7 3 6 5 8 9
3 9 6 4 8 5 2 1 7
2 6 1 5 4 7 9 3 8
4 7 8 3 6 2 1 9 5
9 5 3 1 7 8 4 6 2 ]
which is the first assertion test with the 9 and 7 on row 2 and 7 exchanged

Solution 29087

1 Comment

1 Comment

Trung Duong on 4 Feb 2012

Test 3 is wrong??

Solution 10972

2 Comments

2 Comments

@bmtran (Bryant Tran) on 30 Jan 2012

wtf awesome

Kuifeng on 17 Apr 2012

what is going on...

Problem Recent Solvers279

Problem Tags

Community Treasure Hunt

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

Start Hunting!

Problem 114. Check to see if a Sudoku Puzzle is Solved

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers279

Suggested Problems

More from this Author56

Problem Tags

Community Treasure Hunt

Problem 114. Check to see if a Sudoku Puzzle is Solved

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers279

Suggested Problems

More from this Author56

Problem Tags

Community Treasure Hunt

Players