CR Weekend Challenge

Simon André Forsberg

12:04 AM

Yeah I get the same result now as you posted earlier, @rolfl

rolfl

hehe ... simple things only go so far ... ;-)

Simon André Forsberg

12:15 AM

Yeah, but that feels quite far though

I'm really considering using brute force for the rest

you using X-wing and Swordfish and stuff, @rolfl?

rolfl

Not yet... I am taking the same approach as you.... kill the easy stuff, brute the rest.

I know X-Wing, and stuff, but too lazy to program them in just yet.

Simon André Forsberg

lol

yeah

rolfl

Also, bizarrely, I look at the sudoku where we are, and I can't see a next-step... makes me feel dumb.... ;-)

Simon André Forsberg

At first I actually thought about stopping where I am now, and not completing the assignment entirely (possibly making a complete Java version), but I have come so far now so I just gotta finish it

same here. I'm looking for subsets and stuff but I can't really apply that rule anywhere

rolfl

yeah, but, to brute-force it, I am finding I have to duplicate a lot of sructure in a different way (no validation, etc).

Simon André Forsberg

12:19 AM

Doesn't sound optimal

Time to refactor?

rolfl

No, not refactor, it's because of other reasons... this is 'the right way'.

Simon André Forsberg

ok

rolfl

I amy only submit a small part of the overall process though.

Simon André Forsberg

if you say so ^^

That's how far both I and my program have solved it

Simon André Forsberg

1:15 AM

I have an approach planned for how to brute-force, but way too tired for now so I will continue tomorrow

rolfl

1:30 AM

Sleep well.

retailcoder

3:04 AM

@rolfl wow that's beyond anything I'd hope to come up with in a weekend... I think I'm scoring an F this week...

rolfl

@retailcoder yeah... I looked, and frowned....

That's why I am a 'server' guy .... GUI stuff is new to me.

@retailcoder for what it's worth, I am finding this challenge harder than I expected.

retailcoder

I mean I barely have things defined, I think I'm stumped and it's not the language, I'd be just as stumped in C# :/

Yeah we should have gone for sink-a-ship ;)

rolfl

My first 'naive' brite-force attempt, on the same puzzle as Simon has pictured there (with the same amount of 'solution', is huge..... too long to run on one CPU in an hour.

retailcoder

I'm still at an xmas party, I think I'll end up posting what I have, along with a beginner tag :)

@sim you're already better at C# than me! ;)

rolfl

4:38 AM

@retailcoder - you alive?

rolfl

5:20 AM

Code is a crazy mess.... but, it works (the brute-force of the puzzle works, anyway).

Simon André Forsberg

12:31 PM

@retailcoder @rolfl Ding! Time to get back to C#

Stack Exchange

2:37 PM

0

Q: Sudoku using exact cover solver

1. Introduction This is a solution to Weekend Challenge #3: a Sudoku solver in Python. It works by translating a Sudoku puzzle into an exact cover problem, and then solving the exact cover problem using Donald Knuth's "Algorithm X". The code should be self-explanatory (assuming you've read and u...

Simon André Forsberg

SOLVED!
632845179
471369285
895721463
748153692
163492758
259678341
524916837
986237514
317584926

Simon André Forsberg

2:54 PM

Now it's time for the Simon Certified Extensions (TM)

Jamal

3:25 PM

It's nice to see someone new (Gareth) trying out the challenge. :-)

Simon André Forsberg

Indeed

And it seems like his solution is quite good. Haven't looked at the code yet though (And even if I would, Python is not my second language)

Jamal

I still don't think I'm up for this challenge, and I was just hit with some allergies anyway. Perhaps I'll consider the next challenge.

Simon André Forsberg

Both of these latest challenges has taken more time than I thought they would

What happened to "The project must be a small (tiny!) project that can be completed within a couple of hours"?

Jamal

I guess that depends on the algorithm and the person. :-) Someone else may be able to complete this solver in that time, but it could take me longer.

By the way, have you seen this answer of mine (and the question itself)? I'm only one away from my first Necromancer. I'd say only a smaller portion of the answer is specific to C++.

4

A: Rounding decimals

I agree with the comments implying that floating-point shouldn't be used with money due to issues with precision. Nonetheless, I'll point out some general flaws I've found in your code. There should be a std:: in front of pow(10.0, pos) since you're not using using namespace std. This is not ...

Simon André Forsberg

Nope I missed that one

Congratulations on your first Necromancer :)

Jamal

3:39 PM

Thanks. It felt great getting that zombie. I've had my eye on it for a while, but never quite know how to answer it.

Simon André Forsberg

4:36 PM

I <3 LINQ

2

Jamal

Then why don't you marry it?!?

Simon André Forsberg

I <3 GIRLS

4

Seems like @rolfl has posted his version now

rolfl

He did ... ;

Stack Exchange

0

Q: Sudoku Week-End Challenge - Brute-Force Recursive solver

This is part of my attempt at the Week-End Challenge #3. The overall problem is larger than will fit in one question. This is a well-contained subset of my larger program. The goal of this part is to brute-force all possible (if any) solutions to a puzzle. The input to this algorithm is a 2-dime...

java algorithm recursion weekend-challenge

syb0rg

I have a version to post in C, but it is 1500 lines :P

rolfl

4:50 PM

But it is just the core brute-force algorithm, and some supporting code.

syb0rg

I <3 being hidden

Simon André Forsberg

I'm just gonna test how powerful my solution is, then I will start to actually write my question

Although I wonder if people will understand my code or if I must comment it :P

rolfl

@SimonAndréForsberg - one <3 I want to flag as offensive, the other I want to star.

Simon André Forsberg

haha

Honestly, I'm very impressed with LINQ

I don't know if it has any performance drawbacks, but coding it is so simple. Just a few lines for something that would take two interfaces and five classes in Java (OK, that was an exaggeration...)

Jamal

lol

rolfl

4:52 PM

@SimonAndréForsberg - have you needed LINQ for the sudoku?

Simon André Forsberg

Perhaps not needed, but I've certainly used it

rolfl

Sol LINQ is more than just database access? Huh...

Simon André Forsberg

perhaps overused (if that's possible)

oh yes indeed

you can use it for all IEnumerable types

That is: Collections! :D

Jamal

Someone starred the "lol"? retailcoder must be lurking here. :-)

Simon André Forsberg

_tiles.Where(tile => tile.HasValue) <--- returns an IEnumerable for the _tiles collection to only include those where tile.HasValue equals true

rolfl

5:00 PM

@Jamal - I Spite-starred it! --- you deserve your 'lols' starred too!

retailcoder

5:24 PM

@sim now you understand my pain in leaving LINQ behind!!

Simon André Forsberg

@retailcoder Indeed, but at least you got to work in Eclipse!!

retailcoder

Yeah but I'm not sure all those R#-like bells & whistles make up for no-LINQ!!

Jamal

3

Simon André Forsberg

haha

Jamal

Much better.

Simon André Forsberg

5:29 PM

Don't worry, @rolfl, before you know it I will be a Java guy again.

rolfl

Hmmm ... I think my 'Question' has some interest, but I would not like to be the one who decides to 'review' it .... good luck to them... ;-)(

Simon André Forsberg

I'll take a look at it when I've finished mine

retailcoder

@SimonAndréForsberg that's just LINQ-to-Objects - there's LINQ-to-XML, LINQ-to-SQL, LINQ-to-Entities...

Simon André Forsberg

I feel sorry for the one who has to review my code... I really hope they'll be able to follow my thought process in all this LINQing

retailcoder

@SimonAndréForsberg Don't worry about who will review your C# code :)

With LINQ-to-SQL (and -Entities), you work against an IQueryable, so as long as you don't hit the database until you materialize (i.e. actually iterate) your query. Best thing since sliced bread, I'm telling you!

Simon André Forsberg

5:36 PM

I believe my solution will be complete opposite @rolfl's. He uses low-level primitive values, I use high-level LINQ.

rolfl

@SimonAndréForsberg - yeah, one of my 'trademarks' is that I avoid any heap-space objects in recursion or tight loops. 'My' algorithm has none (other than when it actually finds a solution).

Simon André Forsberg

I guess one of my 'trademarks' is to make stuff as flexible as possible, even when it's not really necessary

syb0rg

Okay, my C Sudoku Solver striped of most of it's features is roughly 85 lines :)

I think it's ready to review

Simon André Forsberg

From 1500 lines down to 85?!? What on earth did you do to it?

3

retailcoder

^^ Ctrl+A, Delete

3

syb0rg

5:41 PM

@SimonAndréForsberg Most of it was command line argument features.

I stripped all of that out.

retailcoder

@syb0rg looks like most of it is an euphemism..

Ok finally got a void Main. Run.. and... ugh (facepalm of despair)

Simon André Forsberg

lol

Exception?

syb0rg

@retailcoder Haha

retailcoder

all of my SudokuDigit instances are null

FML

I think I'll submit my project as "Hello Java World: Parsing a Sudoku Puzzle"

Simon André Forsberg

loop through the 2d-array and create instances perhaps?

remember that when looping through the 2d-array, you must loop through the indexes and set the value in the array.

retailcoder

5:47 PM

All right, my SudokuGrid gets populated now

syb0rg

Here it is:

0

Q: C Sudoku Solver

This is my first attempt at a weekend-challenge. I would prefer if reviews contained suggestions on how to improve the algorithm, but all suggestions are acceptable. Here is the code: #include <stdio.h> int isAvailable(int sudoku[][9], int row, int col, int num) { int rowStart = (row/3) *...

c weekend-challenge sudoku

retailcoder

I'm getting a NullPointerException when trying to output the grid to console. The stack trace sucks.

I mean the same stack trace in C# would mean that Console is null... doesn't make sense, right?

Simon André Forsberg

The stack trace in C# also leaves some things to be desired IMO

what does your line look like?

retailcoder

public static void main(String[] args){
SudokuGrid grid = new SudokuGrid(puzzle);
String result = grid.toString();
System.console().writer().write(result);
System.console().readLine();
}

NPE at System.console().writer().write(result);

Stack Exchange

0

Q: C Sudoku Solver

This is my first attempt at a weekend-challenge. I would prefer if reviews contained suggestions on how to improve the algorithm, but all suggestions are acceptable. Here is the code: #include <stdio.h> int isAvailable(int sudoku[][9], int row, int col, int num) { int rowStart = (row/3) *...

c weekend-challenge sudoku

Simon André Forsberg

5:49 PM

I normally use System.out.print or System.out.println

retailcoder

C# me was looking for a Console :)

Simon André Forsberg

and for reading, use Scanner scanner = new Scanner(System.in); scanner.nextLine();

retailcoder

So what's console for then?

Simon André Forsberg

Never used it TBH

didn't even know System.console() existed until now

retailcoder

OMG I've found something in Java that Simon didn't know about!!

3

(doesn't mean I can use it though)

Simon André Forsberg

5:51 PM

But you haven't figured out how it works yet :)

Damnit, my refactoring have caused my program to not work anymore

rolfl

@SimonAndréForsberg @retailcoder - Console is null for all occasions you run in eclipse, and it is a Java low-level interace to an actual console (think unix TTY, or PTY) (or DOS/Windows 'CON'). When running in eclipse, you may have a STDIN and STDOUT/ERR, but you are not in an actual console.

syb0rg

@rolfl I thought it returned null due to a bug.

rolfl

No, FWIW, I have never had occasion to use a console, but you can do things like intercept control characters, it's unbufferred, etc.... if you need it. But, for most things people do, it will be null (because your JVM is not directly attached to the Console).

OK, I am out-of-here... back in a few hours.

syb0rg

@retailcoder I just discovered I'm not in this post :(

6

A: Call of Duty - We're on a mission

Some "memes"... A few expressions have come up recently, thought I'd share them here (feel free to add, this is CW!) Running out of ammo: when you have exhausted all 40 votes for the day. Head shot: when you're out of ammo and post a target in chat, and then someone puts in a vote for you. Wak...

Simon André Forsberg

@syb0rg What do you want to be known for?

(I wasn't in it either until I added myself)

syb0rg

6:00 PM

@SimonAndréForsberg I didn't know I could add myself...

What do you guys know me for?

Simon André Forsberg

In fact, I added all the personalities that are there

For being involved in the Raspberry Pi SE site

And from now on, for being able to reduce 1500 lines to 85

A good place to start looking is to see which messages you have posted that has been starred:
http://chat.stackexchange.com/rooms/info/11760/cr-weekend-challenge?tab=stars&filter=mymessages
http://chat.stackexchange.com/rooms/info/8595/the-2nd-monitor?tab=stars&filter=mymessages

Jamal

1301 edits so far. That's roughly 12% of the total question count...

retailcoder

@syb0rg being half-robot, half... no one's sure what the other half is :p

2

syb0rg

@SimonAndréForsberg @retailcoder Being a phone-chatting, half-human & half-deficient-robot, refactoring king?

Simon André Forsberg

@syb0rg Sounds about right :)

retailcoder

6:11 PM

It's CW, anybody can edit ;)

Jamal

Anyone with at least 100 rep, specifically.

retailcoder

true

Simon André Forsberg

Surprisingly though, @Jamal still hasn't done so

Jamal

I already have an entry up there, and I have nothing else in mind to add.

retailcoder

Thanks @rolfl, just saw your console explanation.

Simon André Forsberg

6:21 PM

I think it's good that Sudoku is what gets me to try C#, so that I can use all this LINQ stuff

@retailcoder Is it possible to get a random element from a List somehow, in an easy way? (with LINQ?)

retailcoder

@SimonAndréForsberg lol. This is where abusing LINQ gets its meaning from.

Just go .ToList() and myList[someRandomIndex]

Or write your own List<T> extension method that returns a random item?

public static T GetRandom(this List<T> list) { ... }

@SimonAndréForsberg why does every object have an ID in the debugger?

/ where's this ID coming from?

Simon André Forsberg

@retailcoder What do you mean by ID?

retailcoder

Name: this | Value: SudokuGrid (id=17)

Simon André Forsberg

@retailcoder How to get that someRandomIndex? Anything similar to Java's Random class?

No ID(ea) where that ID comes from.

It's just there. It's a nice way though to see whether or not two objects that look similar are actually the same reference

retailcoder

There's a Random class in C# too; var rng = new Random(); var rnd = rng.Next();

Simon André Forsberg

6:32 PM

ok

retailcoder

You can do .Next(min, max); too

But IntelliSense already told you that ;)

@SimonAndréForsberg is there anything like extension methods in Java?

Simon André Forsberg

not sure what extension methods are, @retailcoder

retailcoder

lol

rolfl

heh ... answered a C question ;-)

retailcoder

You've been using them like crazy!

syb0rg

6:35 PM

@rolfl I see that. You did a very good job too.

retailcoder

public static IEnumerable<T> Where(this IEnumerable<T> enumerable, Func<T, bool> predicate) is one

rolfl

... why, thank you ... ;-)

Simon André Forsberg

@retailcoder
public class MyExtensions {
public static int method(String str) {
}
}

I suppose you could use:
import static MyExtensions.*;

And then simply call
method("str");

retailcoder

needs this in the signature

more like using MyExtensions;

hold on

Simon André Forsberg

msdn.microsoft.com/en-us/library/bb383977.aspx

In Java, you can't use this in a method signature like that

retailcoder

6:39 PM

C# is so much more powerful in so many ways that I can now fully appreciate :)

Simon André Forsberg

@retailcoder http://stackoverflow.com/questions/4359979/java-equivalent-to-c-sharp-extension-methods
Java does not support extension methods.
Instead, you can make a regular static method, or write your own class.

Normally in Java, I use public static methods for what you want

Eclipse is so much more powerful in so many ways that I can now fully appreciate :)

retailcoder

With extension methods you can extend (add methods to) any type you want, including stuff in the core libraries, or in 3rd-party code you don't even have sources for.

Kudos for Eclipse though, it's a very nice IDE. Too bad it doesn't do C#

rolfl

Kudos to both of you for jumping your comfort zones for this one!

3

Simon André Forsberg

@retailcoder What did you say? "C# plugin for Eclipse" on StackOverflow

retailcoder

Oh you're shitting me!!

3

Simon André Forsberg

6:43 PM

I have no idea how good it is though, but it's probably worth a try or two :)

retailcoder

meh.. I'd rather keep Eclipse for Java, and VS+R# for C#.

Simon André Forsberg

your choice :)

retailcoder

I'm such a noob. I was doing result.contat("|"); and somehow (don't ask!) expecting the method call to affect result

Simon André Forsberg

Strings are mutable in C#?

retailcoder

no!!

Simon André Forsberg

6:47 PM

lol

retailcoder

that's why I said don't ask!!

eeeh... my grid is all crooked.

at least I got an output

-------------------
| | | |8|4| | | |9|
-------------------
| | |1| | | | | |5|
-------------------
|8| | | |2|1|4|6| |
-------------------
|7| |8| | | | |9| |
-------------------
| | | | | | | | | |
-------------------
| |5| | | | |3| |1|
-------------------
| |2|4|9|1| | | |7|
-------------------
|9| | | | | |5| | |
-------------------
|3| | | |8|4| | | |
-------------------

Simon André Forsberg

looks better inside <pre> :)

retailcoder

^^ obviously didn't spend as much time as @rolfl on fancy cherry-picked ASCII characters

rolfl

Unicode characters!

retailcoder

oh sorry

lol

Simon André Forsberg

6:51 PM

Well, the challenge isn't to make a nice output ^^

rolfl

For every Unicode character I use, I resurrect a baby Unicorn!

2

retailcoder

(removed)

Simon André Forsberg

(removed)

retailcoder

lol!!

rolfl

╔═══╤═══╤═══╦═══╤═══╤═══╦═══╤═══╤═══╗
║ 6 │ 3 │ 2 ║ 8 │ 4 │ 5 ║ 1 │ 7 │ 9 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 4 │ 7 │ 1 ║ 3 │ 6 │ 9 ║ 2 │ 8 │ 5 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 8 │ 9 │ 5 ║ 7 │ 2 │ 1 ║ 4 │ 6 │ 3 ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║ 7 │ 4 │ 8 ║ 1 │ 5 │ 3 ║ 6 │ 9 │ 2 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 1 │ 6 │ 3 ║ 4 │ 9 │ 2 ║ 7 │ 5 │ 8 ║
╟───┼───┼───╫───┼───┼───╫───┼───┼───╢
║ 2 │ 5 │ 9 ║ 6 │ 7 │ 8 ║ 3 │ 4 │ 1 ║
╠═══╪═══╪═══╬═══╪═══╪═══╬═══╪═══╪═══╣
║ 5 │ 2 │ 4 ║ 9 │ 1 │ 6 ║ 8 │ 3 │ 7 ║

Simon André Forsberg

6:51 PM

Then you gotta use a lot of unicode to make up for all the ones we've killed

Jamal

@rolfl: Looks like syb0rg has just invalidated your answers.

rolfl

I'll just revert ... ;-)

Jamal

Alright. Then please comment about that.

syb0rg

@Jamal I posted an edit to rectify it.

(on his answer, all he has to do is accept)

Other than some variable names being changed, his answer is still valid.

retailcoder

-------------------------------------
|   |   |   | 8 | 4 |   |   |   | 9 |
-------------------------------------
|   |   | 1 |   |   |   |   |   | 5 |
-------------------------------------
| 8 |   |   |   | 2 | 1 | 4 | 6 |   |
=====================================
| 7 |   | 8 |   |   |   |   | 9 |   |
-------------------------------------
|   |   |   |   |   |   |   |   |   |
-------------------------------------
|   | 5 |   |   |   |   | 3 |   | 1 |
=====================================
|   | 2 | 4 | 9 | 1 |   |   |   | 7 |

Jamal

6:56 PM

@syb0rg: The first thing that set off my suspicions is that you've removed j from your function.

Simon André Forsberg

I only output a Sudoku grid like this:
040800015
152697834
038451290
019706543
075300080
063508100
320985400
580063900
690000308

syb0rg

@Jamal I forgot about that, and edited it back in real quick.

It's there now.

Jamal

Okay. Make sure everything else checks out.

I'll let rolfl decide on the edit.

syb0rg

@Jamal Looking at the side-by-side markdown, everything checks out.

rolfl

Hehe ... I'll let it all go through...;-)

2

Jamal

6:58 PM

lol

retailcoder

I think this is as good as I'll get it to look:

-------------------------------------
|   |   |   | 8 | 4 |   |   |   | 9 |
-------------------------------------
|   |   | 1 |   |   |   |   |   | 5 |
-------------------------------------
| 8 |   |   |   | 2 | 1 | 4 | 6 |   |
+===========+===========+===========+
| 7 |   | 8 |   |   |   |   | 9 |   |
-------------------------------------
|   |   |   |   |   |   |   |   |   |
-------------------------------------
|   | 5 |   |   |   |   | 3 |   | 1 |

@SimonAndréForsberg just override .ToString() on your Grid class :)

Simon André Forsberg

@retailcoder That's what I do, but I haven't bothered to add all the fancy ASCII (or unicode) output

retailcoder

If only this week's challenge was to parse a string into a Sudoku grid!

Simon André Forsberg

Or actually, I haven't overridden ToString there, but in all my other classes I have

Instead I use a Output method at the moment

retailcoder

@SimonAndréForsberg overriding ToString() on your grid would allow you to output it just like Console.Write(myGrid);

(the .ToString() call is implicit)

Simon André Forsberg

7:04 PM

@retailcoder same in Java

In C#, can you do this?
Console.WriteLine("The value is: " + 42);
I tried that, but it didn't seem to work, I had to call .ToString for my int

retailcoder

Try Console.WriteLine("The value is: {0}", 42);

Then .ToString() will be implicitly called

Otherwise yeah, C# is type-fussy

Simon André Forsberg

OK, yeah I have found that it's possible to do it that way but I find it much easier to use + operator for such small things

retailcoder

Or type-safe as ppl call it

not after you get used to string.Format()

Simon André Forsberg

Java is also type-safe, but the + operator is overloaded for Strings, so that a StringBuilder object is automatically created to concatenate strings

retailcoder

I think in C# it calls string.Contat() under the hood (the + operator is overridden too)

BTW string is a language alias for String - they're the same

except String makes it more obvious that you're dealing with a reference type / class

C# also has a language alias for Object / object

int is a language alias for System.Int32

Simon André Forsberg

7:16 PM

Sometimes I wish there were type aliases in Java too, and that it was possible to make your own

I wonder how many methods I have right now that does not use LINQ

retailcoder

I'll tell you when I review your code :)

Simon André Forsberg

var methodsWithoutLINQ = from method in all_my_methods where method.IsUsingLINQ;
return methodsWithoutLINQ.Count();

retailcoder

lol

you could just do return all_my_methods.Count(method => method.IsUsingLINQ);

^^ Count() has an overload that takes a predicate :)

Simon André Forsberg

ah, yes, that's also an option of course

I think I'm mixing the two ways quite often

not exactly sure when to use which one :P

retailcoder

from myPreferences where IfeelLikeIt select appropriateSyntax is just the same as myPreferences.Where(o => o.IfeelLikeIt)

rigorously identical

syb0rg

7:22 PM

Sweet, my question is the 9th hottest question on the SE network:

5

Q: Sudoku Solver in C

This is my first attempt at a weekend-challenge. I would prefer if reviews contained suggestions on how to improve the algorithm, but all suggestions are acceptable. #include <stdio.h> int isAvailable(int puzzle[][9], int row, int col, int num) { int rowStart = (row/3) * 3; int colStar...

c weekend-challenge sudoku

retailcoder

I prefer the extension methods over the query syntax though

syb0rg

I encourage the carpet-bombing of both answers.

retailcoder

Napalm Strike!!

2

(ka-boom)

rolfl

Whoo hoo ... scored my first 'Nice Question'....

syb0rg

Now has risen to #4 on the SE network!

Simon André Forsberg

7:28 PM

You remember what we have said, @rolfl. The more horrible the code is, the more upvotes the question gets.

3

Jamal

It looks like you have to click on Hot Network Questions to see the question on there. The front view doesn't have this question.

Simon André Forsberg

@syb0rg Don't want to disappoint you, but I'm not so sure everyone sees the same questions there. I don't see your question at all in that list

Ah, oh, there it is

Thanks @Jamal

Jamal

It takes an extra click to see this question. T_T Thanks, ~~Obama~~ SE!

syb0rg

@SimonAndréForsberg I'm looking at the hottest questions from the old hotbar from chat. Maybe they are using a newer algorithm for the hottest questions now.

Jamal

No strikethrough?!?

syb0rg

7:32 PM

@Jamal ~~Nope~~

3

Jamal

There we go.

syb0rg

@Jamal Three - on both sides of text.

Jamal

Already looked at your message to find out. ;-)

►

(because of the "nope")

retailcoder

0

Q: Hello Java World ~> Parsing a Sudoku Grid

This is my first, very-very first attempt at java. I haven't started tackling the actual resolution of the sudoku puzzle (not even sure where to start, haven't looked at other weekend-challenge entries yet). I don't have much to go over here, but I'm sure it's filled with beginner mistakes alread...

java beginner parsing weekend-challenge sudoku

@SimonAndréForsberg ^^

@rolfl ^^^

Simon André Forsberg

@retailcoder I'm on it

syb0rg

7:43 PM

All right, I have to go. Cya guys later.

retailcoder

@syb0rg later!

Jamal

Later!

Stack Exchange

3

Q: Hello Java World ~> Parsing a Sudoku Grid

This is my first, very-very first attempt at java. I haven't started tackling the actual resolution of the sudoku puzzle (not even sure where to start, haven't looked at other weekend-challenge entries yet). I don't have much to go over here, but I'm sure it's filled with beginner mistakes alread...

java beginner parsing weekend-challenge sudoku

retailcoder

@StackExchange duh

2

Simon André Forsberg

@retailcoder

0

A: Hello Java World ~> Parsing a Sudoku Grid

Instead of your String puzzle you could use an String[] like this: (Not saying you have to, but you should know that the alternative exists) You are currently converting it to a String array later anyway, so why not have it as a String array right from the start? private final static String[] p...

15 minutes, HA! Take that, average answering time!

2

retailcoder

7:59 PM

@SimonAndréForsberg thanks for the last paragraph :)

@SimonAndréForsberg oddly, I wrote the string[] constructor before the string one... I just wanted to play with string.split()

Jamal

When I eventually post my first Java program, I suspect it'll really show my C++-side. :-)

retailcoder

ooh @SimonAndréForsberg's answer has been @Jamalized!

Simon André Forsberg

@retailcoder Added some suggestions about Javadoc

retailcoder

My C# side doesn't really shine in a language that doesn't have language-integrated query ...

Simon André Forsberg

Of course it's been @Jamal'ized, I would be surprised if it wouldn't be

retailcoder

8:05 PM

@SimonAndréForsberg in C# you just put /// at the top of a type or method (or property) and poof you've got XML-comments :)

Simon André Forsberg

@retailcoder In Java you just execute javadoc.exe with some parameters and poof, you've got HTML documentation.

retailcoder

You can set an option in the build settings to build a .xml file with all of your xml-comments; I use SandCastle to make a MSDN-style HTML help out of it.

(poof lol)

SandCastle would be equivalent to your javadoc.exe (I believe there's even a command-line to build the HTML)

Simon André Forsberg

yes

retailcoder

So I've got pretty much solid grounds to get started on solving the puzzle right?

Simon André Forsberg

yup

retailcoder

8:14 PM

funny you caught i and j in parseStringContent(String[] contents) - I called them row and col everywhere else!

Simon André Forsberg

@retailcoder Added info about using Character.digit to my answer

retailcoder

what's a radix?

Simon André Forsberg

hexadecimal = 16
decimal = 10
octal = 8
binary = 2

retailcoder

oh

radix => "base"

Simon André Forsberg

yup

retailcoder

8:19 PM

wtf Java

@SimonAndréForsberg is there a Java equivalent to List<T> or I have to stick with arrays?

Simon André Forsberg

you just said it

retailcoder

I'd like to add a List<int> possibleValues;

Simon André Forsberg

List<T> it is

You'll have to use List<Integer> for ints

retailcoder

oh

I miss C# already

Simon André Forsberg

primary types can't be used for generics

retailcoder

8:22 PM

^^ redundant

In C# the T of List<T> can be any object

Simon André Forsberg

List<Integer> possibleValues = new ArrayList<Integer>();

yes, same in Java. However, int is not an Object in Java

retailcoder

wait I can't instantiate a new List<Integer>()

Simon André Forsberg

List is the interface

ArrayList is the most common implementation

retailcoder

in C# (no, in .NET) everything derives from System.Object

in C# List<T> is List<T> : IList<T>

Simon André Forsberg

No primitives? Ugh.

How would @rolfl survive?

retailcoder

8:24 PM

there's System.ValueType

and System.ReferenceType

String is a special reference type, in that it "behaves" like a value type

^^^ immutable

value types are stored on the stack, ref types on the heap. Boxing value types is bad practice and should be avoided.

(same in Java I guess)

@SimonAndréForsberg everything being an object means var words = "hello, world".Split(','); is valid C# :)

Simon André Forsberg

in Java, that would be String[] words = "hello, world".split(",");

retailcoder

ok, try 123.ToString(); :p

Simon André Forsberg

Not much need to call toString for an int in Java

but yes, I noticed it's possible in C#

retailcoder

That was just an example - means you could write an extension method that extends System.Int32, and call it with any instance of the type :)

like, public static bool IsPrime(this int number)

and then do if (4321.IsPrime()) { ... }

Simon André Forsberg

aha

I use wolframalpha for that:
http://www.wolframalpha.com/input/?i=4321&t=mfftb01
`return false;`

:)

retailcoder

8:36 PM

lol

is that a webservice?

Simon André Forsberg

yup

or well...

I don't know if there's any API for it

Jamal

WolframAlpha is awesome.

Simon André Forsberg

but you can do it manually :)

retailcoder

pfft. extension methods are even better.

:)

Jamal

I like to use it when I'm too lazy to differentiate/integrate something. :-)

retailcoder

8:40 PM

private boolean validateDigitValue(Integer value) {
return value == null || (value >= LOWEST_VALID_VALUE && value <= HIGHEST_VALID_VALUE);
}

^^ bye-bye magic numbers :)

Simon André Forsberg

That's more like it!

when I wrote that review for your code, I realized i got plenty of magic numbers myself

How much documentation should I add to the code??

retailcoder

as much as you want to!

Simon André Forsberg

as little as I want to also?

retailcoder

I don't write lots of comments, I like my code self-explanatory :)

^^^ that's what I meant

Simon André Forsberg

What's the naming conventions for constants in C#?

private const int DEFAULT_SIZE = 9; that works?

retailcoder

8:44 PM

C# isn't too fond of ALL_CAPS, the convention is that of a static field, so DefaultSize would do.

Jamal

retailcoder

^^ hmm not quite the clean-code spirit :)

// increments i by 1
i++;

2

Jamal

That, shamefully, half-describes me. I hardly write comments, but I also don't like to make them useless.

Simon André Forsberg

@retailcoder codecrap.com/content/992

2

retailcoder

wow

Nobel prize

Jamal

8:48 PM

By the way, I don't recommend posting that image on comments's wiki. ;-)

> takes three attempts to star something
> assumes all stars have been used up

retailcoder

@SimonAndréForsberg why does public static final int HIGHEST_VALID_VALUE = SudokuGrid.REGION_SIZE*SudokuGrid.REGION_SIZE; work, but not public static final int HIGHEST_VALID_VALUE = SudokuGrid.REGION_SIZE^2;?

Simon André Forsberg

@retailcoder Because ^2 is a XOR operation?

retailcoder

ugh.. what's the operator for "power"

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