Problem 40. Reverse Run-Length Encoder

Created by Cody Team

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{"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>Given a \"counting sequence\" vector x, construct the original sequence y.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>A counting sequence is formed by \"counting\" the entries in a given sequence. This is sometimes called run-length encoding.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>For example, the sequence</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ x = 2, 5, 1, 2, 4, 1, 1, 3]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>can be read as</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ Two 5's, one 2, four 1's, one 3]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>which translates to</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ y = 5, 5, 2, 1, 1, 1, 1, 3]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>So y is the reconstructed vector that corresponds to the counting sequence x.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>For this problem, all elements in the sequences x and y will be in the range from 1 to 9.</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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Last Solution submitted on May 28, 2023

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Carl Witthoft on 17 Nov 2015

See my function "seqle" on FileExchange. It may not be as compact, but it's easy to use and both encodes and decodes.

David Verrelli on 28 Sep 2017

The problem statement would have been clearer if the principle of RLE had been explained with an encoding example first. Alternatively, it would have been useful to explicitly mention that the data in vector x is being read pairwise.

Sanzhar Askaruly on 5 Jul 2019

easy

subbarao satha on 2 Mar 2020

useful challenge

赛鼎薛华 on 11 Jul 2022

useful

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Problem 40. Reverse Run-Length Encoder

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Problem 40. Reverse Run-Length Encoder

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