Problem 307. First non-zero element in each column

Created by Julio

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:t>For a given matrix, calculate the index of the first non-zero element in each column. Assuming a column with all elements zero is not permitted.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><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[ in->x = [0 1 0 0;\n          4 3 7 0;\n          0 0 2 6;\n          0 9 0 5];\n\n out->i = [2 1 2 3]; % row numbers]]></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>"}]}

Solve

Solution Stats

1426 Solutions
595 Solvers

Last Solution submitted on Jan 26, 2021

Last 200 Solutions

Problem Comments

2 Comments

2 Comments

Ned Gulley on 5 Apr 2012

I fixed the test. There was no assert statement.

Dyuman Joshi on 25 Nov 2020

Needs more test cases

Solution Comments

Solution 1844328

1 Comment

1 Comment

Qiaoli Xie on 10 Jun 2019

The test is wrong, the right answer is y_correct = [2 1 3 2];

Solution 1498007

2 Comments

2 Comments

Michael Poppo on 19 Apr 2018

solution is incorrect

Victor Gonzalez on 21 Jun 2018

Not really, we need to determine the first non-zero element in each column, not row.

Solution 600567

1 Comment

1 Comment

Elmar Zander on 3 Mar 2017

The problem is pretty stupid, if there's only one test case. Then you can just return the correct result for this test case, without really computing anything (which is what the "best" solution to this problem does.

Solution 600565

1 Comment

1 Comment

Xiaoyi Chin on 19 Sep 2017

the best answer ! thanks

Solution 133597

1 Comment

1 Comment

Peter Wittenberg on 2 Sep 2012

It looks like I forgot to put in size(x,2) instead of 4. Apparently the test suite didn't check that.

Solution 40473

1 Comment

1 Comment

@bmtran (Bryant Tran) on 14 Feb 2012

yup, definitely an issue...

Solution 40471

1 Comment

1 Comment

@bmtran (Bryant Tran) on 14 Feb 2012

houston we have a problem...

Solution 38585

1 Comment

1 Comment

Julio on 13 Feb 2012

Even you!

Problem Recent Solvers595

Problem Tags

matrix poor_test_suite

Community Treasure Hunt

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

Start Hunting!

Problem 307. First non-zero element in each column

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers595

Suggested Problems

More from this Author10

Problem Tags

Community Treasure Hunt

Problem 307. First non-zero element in each column

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers595

Suggested Problems

More from this Author10

Problem Tags

Community Treasure Hunt

Players