Problem 695. Parse string and identify specific string sequence in algebraic equation

Created by Siva

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{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","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\"?><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>Given a string S that defines an algebraic expression such as:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>S= 'X= A1 + A2*(Y1 + A3*Y3)*exp( A4*Y12 + Y1) ;'</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>return a cell array {'Y1', 'Y12', 'Y123'}</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>i.e. parse the string S and identify the unique variables in the expression that start with the letter \"Y\".</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>"}]}

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127 Solutions
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Last Solution submitted on Sep 26, 2020

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Problem Comments

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Richard Zapor on 1 Jun 2012

I think the correct example solution is {'Y1', 'Y12', 'Y3'}.

Solution Comments

Solution 857811

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1 Comment

William on 28 Mar 2016

Good exercise. Two comments: 1) test case 3 has unbalanced parentheses. 2) Instruction should say that your are expecting results to be returned in sorted order, rather than the order in which they appear in the expression.

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parser regexp string