Generate a valid sequence of numbers with specific rules [closed]

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The challenge

The program must return a valid sequence of numbers into some rules

Rules

x is the size of the sequence;
x cannot be less than 4 or greater than 9 (Thanks David Carraher);
Digits of the sentence can't repeat, each one must appear once;
All digits between 1 to x must be in the sequence;
A valid sequence never begins nor ends with 1 or x;
Into the sequence, numbers can never appear "together";

Examples

If x=4:
2413 valid
3142 valid

1423 not valid, because begins with 1 and 23 are "together".
2134 not valid, because ends with x and 34 are "together".

Still don't get it? Other example:

If x=8:
28375146 valid, because don't start with 1 nor x(8), don't end with 1 nor x, and no numbers are "together"(no numbers touches, no numbers are the next or previous)

Sorry, I really don't know how to explain the last rule. Hope the example make it understandable.

Additional Information

x does not need to be an input, you can show the outputs for x=4 and x=9 working;
Since any language will be accepted and, I don't know how all of them work, I will ask you people to help me with this;
The winner will be the one who got more up-votes in 1 week, so please, vote the answer you find the best; I will mark it as the Correct one;

Good, luck. =)

I recommend you amend the challenge to allow for numbers greater than 9. (Otherwise it is trivial to solve. Consider 952647183, for example.) You can make the challenge much harder by requiring that the answer be given as a list. E.g. {2,4,1,3} — DavidC, Commented Sep 17, 2012 at 3:35

Peter Taylor · Accepted Answer · 2012-09-18 08:02:30Z

2

GolfScript (17 16 chars)

Assuming input on stdin and output on stdout.

~:^),(;{-2\^%?}$

Almost alphanumeric-free...

edited Sep 18, 2012 at 8:02

answered Sep 17, 2012 at 18:33

Peter Taylor

43.1k4 gold badges70 silver badges168 bronze badges

\$\begingroup\$ Oct 31, 2011: Happy Halloween! '?' operator now works correctly for finding substrings in strings, or strings in arrays. Thank you Peter Taylor! Omg Who are you? \$\endgroup\$
– user5403
Commented Sep 17, 2012 at 22:23
\$\begingroup\$ @BernaMariano, that was a pretty small patch. I just happened to notice someone else's question on StackOverflow and realise that string string ? or string array ? could never return anything useful, so I proposed making them do something slightly different. \$\endgroup\$
– Peter Taylor
Commented Sep 18, 2012 at 5:26
\$\begingroup\$ @PeterTaylor Hahahah my next challenge I will add a rule: "Peter Taylor is not allowed to answer" hahaha \$\endgroup\$
– user5403
Commented Sep 20, 2012 at 20:13

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Community · Accepted Answer · 2020-06-17 09:04:33Z

1

Mathematica 38

This simply returns the digits less than or equal to x, in the order in which they appear below.

Row@Select[{2, 9, 6, 4, 7, 1, 8, 5, 3},#<x+1&]

The results from 4 through 9:

output

edited Jun 17, 2020 at 9:04

CommunityBot

1

answered Sep 18, 2012 at 18:58

DavidC

25.4k2 gold badges52 silver badges105 bronze badges

\$\begingroup\$ When x=9 the output breaks a rule, the sequence starts with 9 \$\endgroup\$
– user5403
Commented Sep 18, 2012 at 22:25
\$\begingroup\$ Good catch. I missed that rule. That means that the answer for 5 also doesn't work. \$\endgroup\$
– DavidC
Commented Sep 18, 2012 at 23:18

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score 1 · Accepted Answer · 2012-09-21 02:44:07Z

1

May I try to answer my own challenge?

Javascript (35 chars)

a="1";for(i=x;i>1;i--)a=i%2?a+i:i+a

Outputs

document.write(a);

4 => 2413
5 => 24153
6 => 246153
7 => 2461753
8 => 24681753
9 => 246819753

edited Sep 21, 2012 at 2:44

answered Sep 18, 2012 at 3:01

user5403

\$\begingroup\$ Surely i%2?a+=i:a=i+a can be shortened to a=i%2?a+i:i+a? And i>=2 is trivially i>1 \$\endgroup\$
– Peter Taylor
Commented Sep 19, 2012 at 9:45
\$\begingroup\$ @PeterTaylor Thanks! Actually I tried a=i%2?a+i:i+a but maybe I was doing something wrong because it didn't work, but I did tried this way... The i>1 you are totally right, my bad :P Already edited, now you can vote it up haha \$\endgroup\$
– user5403
Commented Sep 20, 2012 at 3:11

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Matt · Accepted Answer · 2012-09-17 13:48:46Z

0

Haskell 78

a 4=[3,1,4,2]
a x=let b=filter even [1..x]++filter odd[1..x]in tail b++[b!!0]

This defines a function a that takes one parameter, the desired length of the sequence. This function returns a list of numbers in that sequence. I believe this works for x >= 4

This can probably be golfed further (I don't have that much experience in haskell)

Example (in ghci)

ghci> a 4
[3,1,4,2]
ghci> a 9
[4,6,8,1,3,5,7,9,2]

Haskell 25

This version is from before a rule change that now requires that every digit from 1 to x be used exactly once in the sequence

This should work for any sequence of length > 2 (even though the rules only required 4 <= x <= 9)

putStrLn$take x$cycle"02"

Input

The number of digits in the sequence is stored in x.

Output

x = 6 :: Int

x = 4 :: Int

edited Sep 17, 2012 at 13:48

answered Sep 17, 2012 at 11:44

Matt

1,3939 silver badges11 bronze badges

\$\begingroup\$ A recent rule change made this solution wrong. I will fix it soon. \$\endgroup\$
– Matt
Commented Sep 17, 2012 at 12:25
\$\begingroup\$ Looking forward your fix, @Matt! \$\endgroup\$
– user5403
Commented Sep 17, 2012 at 12:28

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scleaver · Accepted Answer · 2012-09-17 14:46:43Z

0

PHP, 64

If I understand the rules correctly, this should work:

for($i=1;$i<=$x;$i++)echo($x%2?2*$i%$x+1:2*$i-($x+1)*($i>$x/2));

If x is odd, this simply cycles through multiples of 2 % x + 1 to produce sequences like 357924681. If x is even, this does the same, but halfway through subtracts 1+x because 2i%x+1 would otherwise never produce even values.

edited Sep 17, 2012 at 14:46

answered Sep 17, 2012 at 14:20

scleaver

5072 silver badges5 bronze badges

\$\begingroup\$ sequences like 357924681 - that one's invalid, because it ends in 1. \$\endgroup\$
– Peter Taylor
Commented Sep 17, 2012 at 14:48
\$\begingroup\$ Ah, ok. I thought it could only not begin in 1. In that case, this type of solution will not work. \$\endgroup\$
– scleaver
Commented Sep 17, 2012 at 14:49
\$\begingroup\$ There is a similar approach which works: count down in odd numbers to 1; then have the largest number; then count up in even numbers from 2. \$\endgroup\$
– Peter Taylor
Commented Sep 17, 2012 at 14:51
\$\begingroup\$ I was hoping to utilize non-trivial generators of the set Z/xZ so that I didn't have to use too many branches. \$\endgroup\$
– scleaver
Commented Sep 17, 2012 at 14:56

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Ilmari Karonen · Accepted Answer · 2012-09-17 16:19:58Z

0

GolfScript, 22 20 chars

~.1|,.+2%(;(@.1&,~;\

Outputs the following sequences for the inputs 4 through 9:

For even inputs, just ~),.+2%(; would suffice. I'm not too happy with the kluge for handling odd input values; there's got to be a more efficient way to do it.

Edit: Saved two chars by changing the output for odd inputs a bit and playing silly stack manipulation tricks. Still not too happy with the length.

edited Sep 17, 2012 at 16:19

answered Sep 17, 2012 at 15:59

Ilmari Karonen

20.8k4 gold badges53 silver badges100 bronze badges

\$\begingroup\$ I really don't get this GolfScript, how can I compile and run this? \$\endgroup\$
– user5403
Commented Sep 17, 2012 at 16:07
\$\begingroup\$ Download the interpreter (a Ruby script) from this site and run it e.g. like this: echo 9 | ruby golfscript.rb program.gs, where program.gs contains the code above. \$\endgroup\$
– Ilmari Karonen
Commented Sep 17, 2012 at 16:16
\$\begingroup\$ You can also check out the GolfScript Interpreter too. \$\endgroup\$
– anon
Commented Sep 17, 2012 at 20:38
\$\begingroup\$ @Mike: ...but if you do, you'll need to hardcode the input into the program (e.g. by prepending ;"INPUT GOES HERE" to the code), since that interpreter doesn't seem to provide a separate field for input. \$\endgroup\$
– Ilmari Karonen
Commented Sep 17, 2012 at 20:47
\$\begingroup\$ @IlmariKaronen, I still don't get it, the echo 9 | ruby golfscript.rb program.gs thing... =( \$\endgroup\$
– user5403
Commented Sep 17, 2012 at 22:28

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olivecoder · Accepted Answer · 2012-09-18 04:59:25Z

0

Python, 37

range(3,x+1,2)+[1]+range(4,x+1,2)+[2])

http://ideone.com/xK40m

edited Sep 18, 2012 at 4:59

answered Sep 18, 2012 at 4:02

olivecoder

3174 silver badges9 bronze badges

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Orabîg · Accepted Answer · 2012-09-18 17:29:46Z

0

Perl 96 chars (obsolete solution since the new rules)

For what I can understand from the rules, we can assume that X is predefined. Then this solution should work :

for(2x$x..9x$x){if(!/^$x/+/$x$/+/1$/){$L=0;map{$d=$L-$_;abs$d>1||next;$L=$_}split//;print;exit}}

which is 96 characters long, although the algorithm is very naive.

It gives the following solutions :

Thus, it seems obvious than there is room to a much simpler program which directly computes a solution of this form...

The following program outputs all valid sequences with any given length X (takes X in STDIN)

$x=<>;$b=10**$x;for($b/10..$b-1){if(!/^$x/+/$x$/+/1$/){$L=0;map{$d=$L-$_;abs$d>1||next;$L=$_}split//;print"$_
"}}

If you want to output ALL possible solutions (for any X), then the program becomes (102 chars) :

for(;;){$x=length$_++;if(!/^$x/+/$x$/+/1$/){$L=0;map{$d=$L-$_;abs$d>1||next;$L=$_}split//;print"$_
"}}

edited Sep 18, 2012 at 17:29

answered Sep 17, 2012 at 12:11

Orabîg

1618 bronze badges

\$\begingroup\$ You updated your solution, but it doesn't follow all the rules. (Your old solution was posted before the rule change) specifically All digits between 1 to x must be in the sequence \$\endgroup\$
– Matt
Commented Sep 18, 2012 at 11:30
\$\begingroup\$ Hey, you're right. This is a huge change ! How are we supposed to play on a moving ground ? ^^ Ok, I'll update my solution if I get some time... \$\endgroup\$
– Orabîg
Commented Sep 18, 2012 at 17:29
\$\begingroup\$ Yeah I'm sorry for not pointing this rule, actually I thought that by just mentioning some examples it would be visible, my fault. \$\endgroup\$
– user5403
Commented Sep 18, 2012 at 18:01

Add a comment |

Gareth · Accepted Answer · 2012-10-29 12:54:17Z

0

Python,30:

' 3579'[:(1+x)/2]+'1468'[:x/2]+'2'

http://ideone.com/3csRh

edited Oct 29, 2012 at 12:54

Gareth

11.3k1 gold badge36 silver badges85 bronze badges

answered Sep 18, 2012 at 5:22

olivecoder

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Stack Exchange Network

Generate a valid sequence of numbers with specific rules [closed]

The challenge

Rules

Examples

Additional Information

9 Answers 9

GolfScript (17 16 chars)

Mathematica 38

Javascript (35 chars)

Haskell 78

Example (in ghci)

Haskell 25

Input

Output

PHP, 64

GolfScript, 22 20 chars

Perl 96 chars (obsolete solution since the new rules)

Python,30:

Hot Network Questions

Generate a valid sequence of numbers with specific rules [closed]

The challenge

Rules

Examples

Additional Information

9 Answers 9

GolfScript (17 16 chars)

Mathematica 38

Javascript (35 chars)

Haskell 78

Example (in ghci)

Haskell 25

Input

Output

PHP, 64

GolfScript, 22 20 chars

Perl 96 chars (obsolete solution since the new rules)

Python,30:

Related

Hot Network Questions