Problem 34. Binary numbers

Created by Cody Team

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Solution Stats

8723 Solutions
2740 Solvers

Last Solution submitted on Jun 11, 2021

Last 200 Solutions

Problem Comments

6 Comments

6 Comments

Show 3 older comments

Jigar Gada on 10 Nov 2012

matlab functions should not be allowed. Let people think of the solution from scratch.

Jon on 18 Nov 2013

I actually use a function to do this in my project, but my original code scored 47.

MDK on 21 Oct 2014

I had all the test cases working properly except for n=10!
This is very weird!!

Gareth Lee on 10 Nov 2014

what's meaning?
when n = 3;
A = binary_numbers(n);
assert(all(A(:) == 0 | A(:) == 1))

Sanzhar Askaruly on 3 Jul 2019

fun!

Anton Casas on 25 Oct 2020

Very fun problem!

Solution Comments

Solution 3890548

1 Comment

1 Comment

Hee Jason on 28 Nov 2020

B = repmat([0 1],1,n);
A = unique(nchoosek(B,n),'rows');

Solution 3041323

1 Comment

1 Comment

SHIVAM SUNDRIYAL on 3 Oct 2020

easy but made me think. nice problem

Solution 2178857

1 Comment

1 Comment

Maryam HCTRAK Yousef on 28 Mar 2020

i can solve it but i have a small mistake

Solution 1857591

2 Comments

2 Comments

Ethan Zhang on 26 Aug 2019

WTF

Chris Liu on 31 Dec 2020

you win

Solution 1751863

1 Comment

1 Comment

Naman Bhaia on 15 Mar 2019

de2bi() function is not working for this code. Solves the problem when you run it on MATLAB

Solution 1633817

1 Comment

1 Comment

Yoshinobu Kawada on 26 Sep 2018

I correct my comments in the source code.
It was 'Column', not 'Row'.

'Column 1 is 0 1 0 1 ..., column 2 is 0 0 1 1 ... , continue to column n.'

Solution 1460452

1 Comment

1 Comment

Da Lu on 11 Mar 2018

用了一个多小时才解决这个
got me one more hour to solve this

Solution 1405784

2 Comments

2 Comments

Ajay Rawat on 5 Jan 2018

In the third test i.e, for n=5, shouldn't the size (A) be compared to [31 5] instead of [32 5] ?

Burak Bayram on 8 Feb 2019

I didn't even tried to do that, but yeah in example it's 8x3 ( n^2-1 x n) matrix but then it asks 32x5 for n=5 ... quite odd

Solution 1281878

2 Comments

2 Comments

Ian Harrison on 5 Oct 2017

Undefined function 'de2bi' for input arguments of type 'double'...

http://uk.mathworks.com/help/comm/ref/de2bi.html ...

Simon Thomas on 9 Nov 2017

de2bi is part of the 'Communications System Toolbox'

Solution 1246760

3 Comments

3 Comments

fkk on 5 Aug 2017

I've just solved this problem by the code that "A=(dec2bin(0:2^n-1)-48);" How it could be that the size of leading solution is 9,but mine is 21 !?

Michael Böhm on 15 Aug 2017

could you pls explain the "-48" to me? i see what it does, but dont know why...

Allen on 12 Oct 2017

fkk,
There is a regexp() trick that some people use to produce very small sized answers. However, they do not necessarily produce a correct solution to the real world problem. I tend to proud that my answers correctly solve the problem, regardless of their size. It is a shame that the regexp() exploit is not discouraged.

Michael Bohm,
When using a numerical operator against a character vector, MATLAB interprets the char-vec as a numerical vector with values that correspond to the ASCII values. As such, the ASCII values can be passed through the char() function to produce the original char-vec. i.e. ---> char('Some Text'+1) = 'Some Text'

Solution 824453

1 Comment

1 Comment

Brendan Gray on 11 Feb 2016

The test suite is poorly designed. A better test would be
assert(length(unique(sum(A.*repmat(2.^(0:(n-1)),2^n,1),2)))==2^n)

Solution 816928

1 Comment

1 Comment

simonflossmann on 30 Jan 2016

Why is it not possible to use de2bi?

Solution 793634

1 Comment

1 Comment

Fatpuss on 13 Dec 2015

One ugly line

Solution 724614

1 Comment

1 Comment

Raihan Ahmed on 27 Aug 2015

Can anybody please explain the size ???? I just wrote 1 line !!!

Solution 699755

1 Comment

1 Comment

Swapnil Kulkarni on 13 Jul 2015

Whats wrong in this ?

Solution 580909

2 Comments

2 Comments

Philemon Chavrier on 13 Feb 2015

Worst Solution ever!!^^

Fatpuss on 13 Dec 2015

Excellent

Solution 580854

1 Comment

1 Comment

Jerivington on 30 May 2016

lool

Solution 490151

1 Comment

1 Comment

Harish Maradana on 25 Aug 2014

function ans = binary_numbers(n)
str2num(dec2bin(0:2^n-1));
end test suit 2 3 fails bit 1 4 5 pass help me

Solution 353843

2 Comments

2 Comments

Rahul on 17 Nov 2013

function A = binary_numbers(n)
A = dec2bin(0:2^n-1);
end

This should give the correct solution, but fails in the Test Suite!!!

Jon on 18 Nov 2013

Not sure about tests 2 and 5, but test 1 requires a type 'double' answer. Your code returns a type 'logical' answer.

Solution 241043

2 Comments

2 Comments

Mineralter on 26 Jun 2013

Good Job!

Vivek on 18 Jul 2013

Cant able to understand the problem. Please explain me

Solution 175648

1 Comment

1 Comment

sea knowledge on 13 Dec 2012

how can you come up with such a sotlution,l thought for a long time,still have no shorter solution

Solution 172028

1 Comment

1 Comment

Felix on 3 Dec 2012

The test suite for this solution does not seem to work properly.

Solution 163819

2 Comments

2 Comments

Maria on 18 Nov 2012

Error: Undefined function 'ff2n' for input arguments of type 'double'.

Edgar Guevara on 3 May 2013

Use of ff2n is no longer allowed; we are not competing in the same league as the first contestants

Solution 117485

1 Comment

1 Comment

Andrew Newell on 7 Jun 2013

I have never seen 'ans' used this way before!

Solution 81971

1 Comment

1 Comment

Binbin Qi on 25 Apr 2012

no de2bi?
no fullfact?

Solution 81969

1 Comment

1 Comment

Binbin Qi on 25 Apr 2012

why not this function ff2n?

Solution 62102

2 Comments

2 Comments

Cris Luengo on 14 Jul 2012

They should disallow toolbox functions... this one doesn't work for me!

Gareth Lee on 1 Dec 2014

good answer function!

Solution 8199

4 Comments

4 Comments

Show 1 older comment

Jean-Yves Tinevez on 30 Jan 2012

A masterpiece!
How did you get the idea?

Alex Brown on 7 Feb 2012

I mean it's certainly short... but pretty inefficient...

Trung Duong on 9 Feb 2012

what does the 'size' mean? It's ridiculous :)

Nathaniel on 11 Mar 2012

@Jean-Yves, having arrived at the same idea, it is from #4 in the test suite for this problem.

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Problem 34. Binary numbers

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Problem 34. Binary numbers

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