Problem 1826. Find vampire numbers

Created by Andrew Newell

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>A</w:t></w:r><w:r><w:t> </w:t></w:r><w:hyperlink w:docLocation=\"http://en.wikipedia.org/wiki/Vampire_number\"><w:r><w:t>vampire number</w:t></w:r></w:hyperlink><w:r><w:t> is a number v that is the product of two numbers x and y such that the following conditions are satisfied:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"2\"/></w:numPr></w:pPr><w:r><w:t>at most one of x and y are divisible by 10;</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"2\"/></w:numPr></w:pPr><w:r><w:t>x and y have the same number of digits; and</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"2\"/></w:numPr></w:pPr><w:r><w:t>The digits in v consist of the digits of x and y (including anyrepetitions).</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>If these conditions are met, x and y are known as \"fangs\" of v. For example, 1260 is a vampire number because 1260 = 21*60, so 21 and 60 are the fangs.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Write a function that returns all the vampire numbers in a given array. The output is a vector.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Example: disp(find_vampire(1000:2000) 1260 1395 1435 1530 1827</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>See also: </w:t></w:r><w:r><w:t> </w:t></w:r><w:hyperlink w:docLocation=\"http://www.mathworks.com/matlabcentral/cody/problems/1825-find-all-vampire-fangs\"><w:r><w:t>Problem 1825. Find all vampire fangs</w:t></w:r></w:hyperlink><w:r><w:t> and</w:t></w:r><w:r><w:t> </w:t></w:r><w:hyperlink w:docLocation=\"http://www.mathworks.com/matlabcentral/cody/problems/1804-fangs-of-a-vampire-number\"><w:r><w:t>Problem 1804. Fangs of a vampire number</w:t></w:r></w:hyperlink><w:r><w:t>.</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>"}]}

A <a href = "http://en.wikipedia.org/wiki/Vampire_number">vampire number</a> is a
number v that is the product of two numbers x and y such that the
following conditions are satisfied:<ol><li>at most one of x and y are divisible by 10;</li><li>x and y have the same number of digits; and</li><li>The digits in v consist of the digits of x and y (including any
repetitions).</li></ol>If these conditions are met, x and y are known as "fangs" of v. For
example, 1260 is a vampire number because 1260 = 21*60, so 21 and 60 are
the fangs.Write a function that returns all the vampire numbers in a given array.
The output is a vector.Example:
 disp(find_vampire(1000:2000)
 1260 1395 1435 1530 1827See also:
 <a href = "http://www.mathworks.com/matlabcentral/cody/problems/1825-find-all-vampire-fangs">Problem 1825. Find all vampire fangs</a> and <a href = "http://www.mathworks.com/matlabcentral/cody/problems/1804-fangs-of-a-vampire-number">Problem 1804. Fangs of a vampire number</a>.

Solve

Solution Stats

408 Solutions
156 Solvers

Last Solution submitted on Aug 06, 2020

Last 200 Solutions

Problem Comments

2 Comments

2 Comments

Rafael S.T. Vieira on 16 Jul 2020 at 3:18

Are you sure about the first rule? It doesn't seem necessary according to https://oeis.org/A014575.

Adib on 27 Jul 2020 at 7:08

The problem is really fun.

Solution Comments

Solution 1183879

2 Comments

2 Comments

Andrew Newell on 9 May 2017

Since I created the problem series and want the Functions I badge, I thought I'd provide the solution that incorporates vampire_factor and are_fangs. Not a great score, but readable!

Andrew Newell on 9 May 2017

Sorry, I mean the Magic Numbers badge.

Solution 678164

1 Comment

1 Comment

danteliujie on 7 Apr 2019

Like it

Problem Recent Solvers156

Problem Tags

factors number theory

Problem 1826. Find vampire numbers

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers156

Suggested Problems

More from this Author9

Problem Tags

Problem 1826. Find vampire numbers

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers156

Suggested Problems

More from this Author9

Problem Tags

Players