I am creating a Sudoku project in vb.net, to such an end I need to store a list of all the possibilities for each square where the squares are indexed by one number. for example the computer needs to know that for square [8] the numbers {1,3,5,9} are possible etc... I began by using a jagged array however there is no apparent 'remove' method which needs to be called a lot. this makes my code looks ugly with all the redim statements in it and so I was curious as to whether a list or arraylist would be best suited to my purposes? I have discovered arraylists have a remove method but I have also read that array lists are all but deprecated and i want to know if there is a nicer solution to this.
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I need to add an array of non-adjacent cells to my array formula. I have tried all of the following array constant-like ways and they all give me a "There is a problem with this formula error".
'Chart Data'!{A12:A14,D3:D11}
{'Chart Data'!A12:A14,'Chart Data'!D3:D11}
'Chart Data'!{A12,A13,A14,D3:D11}
{'Chart Data'!A12,'Chart Data'!A13,'Chart Data'!A14,'Chart Data'!D3:D11}
'Chart Data'!{A12,A13,A14,D3,D4,D5,D6,D7,D8,D9,D10,D11}
{'Chart Data'!A12,'Chart Data'!A13,'Chart Data'!A14,'Chart Data'!D3,'Chart Data'!D4,'Chart Data'!D5,'Chart Data'!D6,'Chart Data'!D7,'Chart Data'!D8,'Chart Data'!D9,'Chart Data'!D10,'Chart Data'!D11}
Entire formula (the array constant goes where the {#####} is):
{=SUM(((1-References!M1:M12)*({#####}*(G3:G14+F3:F14-0.11)))+((References!M1:M12)*('Chart Data'!A12:A23*(G3:G14+F3:F14-0.11)))+((H2:H13*X3:X14)+(H3:H14*Y3:Y14)+(I2:I13*(V3:V14-X3:X14))+(I3:I14*(W3:W14-Y3:Y14))))}
I am 100% positive that it is this particular array constant that is causing the problem. I can't move the cells I'm referencing to put them in line. Is it even possible to reference a non-adjacent range in an array formula? If it's possible, what am I doing wrong?
There are several ways to do this. The following is very simple and pretty direct so my favorite.
EITHER choose a cell to build your string for your non-contiguous array in OR create a Named Range to do it. I'll show the first as it seems nicest for being able to use the mouse freely, but in both of them you can actually be creative using about how you build the string that will become your array. The main advantage of creating it in a Named Range is no helper cell lying about anywhere.
So, you create that string and then make it an array. Say you have a non-contiguous array needed using cells A12:A14 and C3:C11. You use joining and TEXTJOIN() like so:
="{"&TEXTJOIN(",",FALSE,B12:B14,C3:C11)&"}"
to create a text string of the values in those cells wrapped with the curly braces ({}) just as if you'd typed it in ("hardcoded it"). It will look like this with the right values in those cells:
{1,2,3,1,2,3,4,5,6,7,8,9}
but is ain't an array yet.
Now the magic in THIS method. Create a Named Range, perhaps called String2Array, and give it a formula of:
=EVALUATE(A1)
(or whatever cell you used for the above formula creating the text string that you want to be an array). Make the reference absolute. ($A$1... which it will do for you, just don't edit it to be relative. If you use this for similar work, but need it relative, that will work fine, but it just isn't what is needed here.)
Now replace your placeholder in the formula with the Named Range's name (perhaps you DID use String2Array). And you're done.
A couple other methods use INDEX() or CHOOSE() and you can force things to be arrays using the functions DOLLARDE() and IMREAL() (I found on a helpsite in a 2014 post) and some others do the same kind of thing. In those days, one had to use {CSE} too, but SPILL takes care of that now (with those two weird-seeming friendlies and at least two others). The poster was someone I've seen on this site, EXCELXOR was the name for the site, XOR LX was the name of the member here though the functions were mentioned in a comment by a Lori. Since he covers, it seems, aspects not usually covered in helpsites, looking up some of his work here, or elsewhere too, might be worthwhile to some folks.
But this method is very direct and therefore easy to maintain. And personally, I love the idea that EVALUATE() (must be used IN the Named Range functionality, not cell-side) is the gift that keeps on giving, one wonderfully helpful thing after another.
So many ways. You could even literally build the array in a helper column/row somewhere and reference THAT instead of the non-contiguous addresses. I like the joining+TEXTJOIN() approach best because I can use the mouse to easily get all the blocks into the formula since it is a LIVE formula. But you can type out a string fairly easily too and add the {}'s. Or perhaps a user would type a string of addresses and you'd add them like the formula does above. And you can insert actual values (constants) into the string you are building as well if that is appropriate. And you could build it formulaicly... I wouldn't pick that workload first thing off the pile of choices, but if you were going to do it anyway already, then... or if it's a small build.
This might be frivolous question, so please have understanding for my poor soul.
After reading this article about Intelligent Design sort (http://www.dangermouse.net/esoteric/intelligentdesignsort.html) which is in no way made to be serious in any way, I started wondering whether this could be possible.
An excerpt from article says:
The probability of the original input list being in the exact order it's in is 1/(n!). There is such a small likelihood of this that it's clearly absurd to say that this happened by chance, so it must have been consciously put in that order by an intelligent Sorter.
Let's for a second forget about intelligent Sorter, and think about possibility that random occurrences of members in array are in some way sorted. Our algorithm should determine the pattern without changing array's structure.
Is there any way to do this? Speed is not a requirement.
The implementation is very easy actually. The entire point of the article is that you don't actually sort anything. In other words, a correct implementation is a simple NOP. As my preferred language is Java, I'll show a simple in-place implementation in Java as a lambda function:
list->{}
Funny article, I had a good laugh.
If the only thing you're interested in is that whether your List is sorted, then you could simply keep an internal sorted flag (defaulted to true for an empty list) and override your add() method to check if the element you're adding fits the ordering of the List - that is, compare it to the adjacent elements and setting the sorted flag appropriately.
There is ${name//pattern/string} and ${name:pos:len} for strings but I haven't found any similar documentation for manipulating arrays.
So far I've just been using shift and/or unset for simple manipulation. The only other plausible alternative would be to loop over the values and reconstitute a new array but that isn't desirable.
mksh developer here ;-)
This is not yet implemented currently, to answer your question. It has been on the TODO for a while already, going as far as to be a comment in the source code file in question, so it will probably materialise some day (a good chance to add it is when we’ll have multi-dimensional and associative arrays added, which prompts a partial rewrite of the code in question anyway).
I have question relating to implementation of arrays with Java+ANTLR combo. (I'm mainly talking about java/c style arrays).
So basically I'm asking how do you implement such feature, if there is such example already available or if someone could point me to anything that may point to solve it.
On other hand, I've searched a bit how would possible solution be. Main problem that I see
is that user may create arrays of various dimensions, even go crazy if he or she wants (like creating 5 dimension arrays or worse).
While grammar for something like this is fairly simple, like
new ID (INT (',' INT)* )
back end really gets involved a bit. As I said, user may input any number of dimensions, so array dimensions should be dynamically created. (at least as I see it, maybe I'm over complicating things?)
After searching I did found something that pretty much solves this problem perfectly, here is link to the question:
Is it possible to dynamically build a multi-dimensional array in Java?
Of course, my question is, is this viable example, it is a bit (to say at least), complicated? Is there more elegant solution to it?
Having that in mind, I was thinking maybe answer might be in the grounds of somehow transforming multidimensions
into more linear structure ? Could something like that be useful ? Simple search on stackoverflow pointed many solutions
to this, like:
Algorithm to convert a multi-dimensional array to a one-dimensional array
Would it be worth to search in that direction ?
Now, at the end, having in mind that arrays are really common feature in many languages, I must find it surprising that after searching ANTLR mailing list there is no similar question, which as I previously said leads me to believe that I'm maybe over complicating things ? (Unless I really suck at search?) I would really appreciate feedback.
Your syntax, if I'm not mistaken, corresponds to something like
new char 4,5,6,7
which is kind of strange. I expect that you really meant
new char[4,5,6,7]
However from a purely syntactic point of view, there's no reason not to just store the indices in an array and let the semantic analysis pass worry about it.
I was thinking to implement MD5 as a code kata and wanted to use BDD to drive the design (I am a BDD newb).
However, the only test I can think of starting with is to pass in an empty string, and the simplest thing that will work is embedding the hash in my program and returning that.
The logical extension of this is that I end up embedding the hash in my solution for every test and switching on the input to decide what to return. Which of course will not result in a working MD5 program.
One of my difficulties is that there should only be one public function:
public static string MD5(input byte[])
And I don't see how to test the internals.
Is my approach completely flawed or is MD5 unsuitable for BDD?
I believe you chose a pretty hard exercise for a BDD code-kata. The thing about code-kata, or what I've understood about it so far, is that you somehow have to see the problem in small incremental steps, so that you can perform these steps in red, green, refactor iterations.
For example, an exercise of finding an element position inside an array, might be like this:
If array is empty, then position is 0, no matter the needle element
Write test. Implementation. Refactor
If array is not empty, and element does not exist, position is -1
Write test. Implementation. Refactor
If array is not empty, and element is the first in list, position is 1
Write test. Implementation. Refactor
I don't really see how to break the MD5 algorithm in that kind of steps. But that may be because I'm not really an algorithm guy. If you better understand the steps involved in the MD5 algorithm, then you may have better chances.
It depends on what you mean with unsuitable... :-) It is suitable if you want to document a few examples that describes your implementation. It should also be possible to have the algorithm emerge from your specifciation if you add one more character for each test.
By just adding a switch statement you're just trying to "cheat the system". Using BDD/TDD does not mean you have to implement stupid things. Also the fact that you have hardcoded hash values as well as a switch statement in your code are clear code smells and should be refactored and removed. That is how your algorithm should emerge because when you see the hard coded values you first remove them (by calculating the value) and then you see that they are all the same so you remove the switch statement.
Also if your question is about finding good katas I would recommend lokking in the Kata catalogue.