I need to implement Minesweeper solver. I have started to implement rule based agent.
I have implemented certain rules. I have a heuristic function for choosing best matching rule for current cell (with info about surrounding cells) being treated. So for each chosen cell it can decide for 8 surroundings cells to open them, to mark them or to do nothing. I mean. at the moment, the agent gets as an input some revealed cell and decides what to do with surrounding cells (at the moment, the agent do not know, how to decide which cell to treat).
My question is, what algorithm to implement for deciding which cell to treat?
Suppose, for, the first move, the agent will reveal a corner cell (or some other, according to some rule for the first move). What to do after that?
I understand that I need to implement some kind of search. I know many search algorithms (BFS, DFS, A-STAR and others), that is not the problem, I just do not understand how can I use here these searches.
I need to implement it in a principles of Artificial Intelligence: A modern approach.
BFS, DFS, and A* are probably not appropriate here. Those algorithms are good if you are trying to plan out a course of action when you have complete knowledge of the world. In Minesweeper, you don't have such knowledge.
Instead, I would suggest trying to use some of the logical inference techniques from Section III of the book, particularly using SAT or the techniques from Chapter 10. This will let you draw conclusions about where the mines are using facts like "one of the following eight squares is a mine, and exactly two of the following eight squares is a mine." Doing this at each step will help you identify where the mines are, or realize that you must guess before continuing.
Hope this helps!
I ported this (with a bit of help). Here is the link to it working: http://robertleeplummerjr.github.io/smartSweepers.js/ . Here is the project: https://github.com/robertleeplummerjr/smartSweepers.js
Have fun!
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've tried looking on google but i guess I can just not get the right search phrases to find what I want. If you are familiar with the afterNET IRC server, there is a command '.8' which is an 8 ball. It answers more than just yes/no questions tho. It gives you a variety of answers based on certain words you use in your question, like when, where, color, etc
I'd like to make something like this but have no idea where to start. I've recently studied DFA (Deterministic Finite Automata), is that where I should start? I understand I don't want to be scripting out every possible combination of words people use, but it would be nice to have a system that feels sorta realistic (like the 8ball program on the IRC server), and is expandable for more 'words' whenever I want.
Thanks for any help/links!
You may be giving most 8ball implementations more credit than they deserve. I think the point is that the questions are for yes/no answers, so the provided answers only have to cover a fairly predictable set of possibilities.
Most 8ball scripts that I am aware of (example) will just use an array and a random number to grab an answer.
Magic 8ball bots are very popular on irc as they are very easy to implement - simply respond to text with a given marker (in this case ".8") and respond with a random answer.
I have never heard of a magic 8ball using a deterministic approach, Cleverbot style. Actually, trying that, I'm not even sure how deterministic that is as most of the responses are also totally random and unrelated to what I was saying.
// our answers array
String[] answers = [ "yes", "no", "for sure", "unlikely", "most certainly", "definitely not" ];
public String ask8Ball() {
// rand returns a float between 0>=res>1, the (int) cast rounds down
int index = (int)(java.lang.Math.random() * 7);
return answers[index];
}
What is the proper way to name my revisions?
v1.0.3.20 Alpha
or
Alpha v1.0.3.20
There isn't really any "proper" way. While most people use the dot pattern "x.x.x", it isn't necessarily the proper way to do it. Likewise with your question, it is up to you.
I would suppose that the former is more natural to say, and I would prefer it, but it doesn't really matter either way.
You have two pieces of information there: version number and release state/quality. The two might be tied together, but don't have to be. For example, you could have multiple "releases" for a single version number: v1.1-alpha, v1.1-beta, v1.1-final, and so forth; or you could break those down into individual numbers: v1.0.1-alpha, v1.0.2-beta, v1.1.0-final; or something entirely different!
This is really a question of branding more than anything; due to the wide interpretation of version info across different products, you already have to know how each different product uses them to make sense of it. Of course, if you're contributing to, working with, or emulating another project: do what they do. It'll be simpler and lead to less confusion.
As used in my examples, I'd prefer "n.n...-quality", but it's only syntax.
Recently I tried to explain some poorly designed code to my project manager. All of the manager classes are singletons ("and that's why I can't easily change this") and the code uses event dispatching everywhere that a function call would have sufficed ("and that's why it's so hard to debug"). Sadly it just came out as a fumbling mess of English.
Whats the most difficult thing you've had to convey to a non-technical person as a programmer? Did you find any analogies or ways of explaining that made it clearer?
Thread Synchronization and Dead-Locking.
Spending time on design, and spending time on refactoring.
Refactoring produces no client-visible work at all, which makes it the hardest thing in the project to justify working on.
As a second "not client-visible" problem, unit testing.
I was asked how the internet worked - I responded with "SYN, ACK, ACK". Keep forgetting it's SYN, SYN-ACK, ACK..
(source: inetdaemon.com)
My most difficult question began innocently enough: my girlfriend asked how text is rendered in Firefox. I answered simply with something along the lines of "rendering engine, Gecko, HTML parser, blah blah blah."
Then it went downhill. "Well how does Gecko know what to display then?"
It spiraled from there quite literally down to the graphics drivers, operating system, compilers, hardware archiectures, and the raw 1s and 0s. I not only realized there were significant gaps in my own knowledge of the layering hierarchy, but also how, in the end, I had left her (and me!) more confused than when I began.
I should've initially answered "turtles all the way down" and stuck with that. :P
I had a fun case of trying to explain why a program wasn't behaving as expected when some records in a database had empty strings and some were NULL. I think their head just about exploded when I told them empty string is just a string with 0 bytes in it while NULL means unknown value and so you can't actually compare it to anything.
Afterward I had one nasty headache.
1.) SQL: Thinking in sets, rather than procedurally (it's hard enough for us programmers to grasp!).
2.) ...and here's a great example of demystifing technical concepts:
How I explained REST to my wife
A lot of statements starting with "It's because in Oracle, ..." come to my mind.
The biggest hurdles are around "technological debt", especially about how the architecture was correct for this version but needs to be changed for next version. This is similar to the problem of explaining "prototype versus production" and "version 1.0 versus version 2.0".
Worst mistake I ever made was doing a UI mockup in NeXT steps UI Builder. It looked exactly like the end product would look and had some behaviour. Trying to explain that there was 6 months of work remaining after that was very difficult.
How recursion works...
Why code like this is bad:
private void button1_Click(object sender, EventArgs e)
{
System.Threading.ThreadStart start =
new System.Threading.ThreadStart(SomeFunction);
System.Threading.Thread thread = new System.Threading.Thread(start);
_SomeFunctionFinished = false;
thread.Start();
while (!_SomeFunctionFinished)
{
System.Threading.Thread.Sleep(1000);
}
// do something else that can only be done after SomeFunction() is finished
}
private bool _SomeFunctionFinished;
private void SomeFunction()
{
// do some elaborate $##%#
_SomeFunctionFinished = true;
}
Update: what this code should be:
private void button1_Click(object sender, EventArgs e)
{
SomeFunction();
// do something else that can only be done after SomeFunction() is finished
}
private void SomeFunction()
{
// do some elaborate $##%#
}
The importance of unit tests.
"Adding a new programmer a month to this late task will make it ship later. Never mind, read this book." (The Mythical Man-Month.) Managers still don't quite get it.
The concept of recursion - some people get it really hard.
I sometimes really have hard time explaining the concept of covariance/contravariance and the problems related to them to fellow programmers.
Convincing a friend that the Facebook application I developed really doesn't store her personal data (e.g. name) even though still displays it.
Why it'll take another four weeks to put this app into production. After all, it only took a week to do the rapid prototype. It "works" (or at least looks like it does) so I should be pretty much finished, shouldn't I?
Explanations that involve security, code quality (maintainability), normalized DB schemas, testing, etc. usually come off as a list of abstractions that don't have any visible effect on the app, so it's hard to explain what they really contribute to the project and why they're necessary. Sometimes analogies can only take you so far.
C pointers
*i
&i
Avoiding Dead-Locking in a multi-threaded environment.
I cleared confusion by explaining it visually on a white-board, drawing out two parallel lines and showing what happens when the reach the same points at the same time.
Also role-playing two threads with the person I was explaining it to, and using physical objects (book, coffee mug, etc) to show what happens when we both try to use something at once.
There's really no right or wrong answer-proper for this... it's all experiences.
The hardest thing I have had to explain to a non-tech person was why he couldn't get to his website when traveling abroad but his family member that lived there (with a totally different provider) could get to it. Somehow, "Fail in Finland" wasn't good enough.
The most difficult concepts to explain to people I would label programmers as opposed to developers are some of the most core paradigms of object orientated design. Most specifically abstraction, encapsulation and the king, polymorphism and how to use them correctly.
Expanding on that is the level of complexity of explaining what Inversion of Control is and why it is an absolute need and not just extra layers of code that doesn't do anything.
I was going to comment on Mikael's post, that some people just take the sequential programming and unfortunately just stay with that.
But that really means: two seriously hard to explain concepts:
monads in haskell (usually starting with: "That's like a function that returns a function that does what you really wanted to do, but ...")
deferreds in twisted/python ("That's like... ehhh... Just use it for a year or so and you'll get it" ;) )
Trying to explain why code was executed sequentially at all. Seemingly this is not at all intuitive for some non-programmers (i.e. my girlfriend).
Why you do not need character correct index handling in most cases when you use UTF-8 strings.
It's hard to explain why most software has bugs. Many non-technical people have no idea how complex software is, and how easy it is to overlook unexpected conditions. They think we are just too lazy to fix stuff that we know is broken.
There are 10 different types of people in the world.
The people who understand Binary and the people who dont....
To put it plainly, why development is the most difficult concept ever exposed to man kind. Not related to any programming language, but in general. And no I am not trying to provide myself or you with an ego boost, the only real limitations to this field is your mind.
Why? We don't work with constants and there are no boundaries, the only reason an AI that thinks like a human being doesn't exist yet is due to our own limitations. All other aspects need to adhere to some sort of law, development doesn't care about the laws of physics or any law for that matter hence the term development... evolution.