Hackerrank practice challenge showing errors - language-agnostic

Can anyone just try solving the problem https://www.hackerrank.com/challenges/staircase
I don't want the solution, I just think that it is not showing correct solution even when my code is right. Just tell me if the problem is fine and your solution is running error free.

Yes -- I don't know what language you're using, but I did that one in Python a couple years ago with no problem.

Related

Trying to understand JSON better: Load/Dump vs Encoder/Decoder, how are they different?

So looking through the similar questions section there seems to be a lot of similar questions but none that are helpful in understanding what I need to understand or I'm just generally not getting what they are putting down. I'm studying python and up to the JSON part of it however as I do understand most of it loading, dumping, etc. I am having issues understanding the proper encoding/decoding part of it "json.encoder", etc.
Reading over the python documents, the information there is a little hard for me to understand therefore I can't write my own notes on it. Every site or video I've seen doesn't explain the terms json.encoder and json.decoder but simply just go over loads and dumps.
I have understood everything else till this point, but can't continue till I fully understand it so any help is greatly appreciated.
So my question is:
What are the differences exactly between encoding/decoding using loads/dumps and encoder/decoder?

Google-Apps-Script editor not suggesting function? (auto completion)

Sometimes when I'm writing a script in google docs, the environment just stops suggesting functions when I type a ".". Any one know what this might happen? I can not pinpoint anything I am doing to cause it, and can not replicate the problem, it just happens randomly.
This happens sometimes when you try to save a version with a syntax error but also for no apparent reason. I remember the subject has been discussed on SO already and that a few people commented on this but I just can't remember when nor find the related post. Anyway, there is no really efficient way to make it work again...
When it happens to me I usually create a new project and copy/paste the code in it... not very smart but at least it works.
I'd be glad if someone could suggest an better way to fix it or knows the exact origin so I could avoid to let it happen (since I use A LOT the autocompletion feature :-).
PS : this is not really an answer, I know but it was definitely to long to fit in a comment.

Connect to MySQL directly from an iPad app (not via PHP, etc.)

Before anyone has a chance: Yes, i know it's a bad idea. Please, don't give me a lecture on how i should use a web service instead. Thanks.
So, how could this be done?
I found this bit http://www.karlkraft.com/index.php/2010/09/17/mysql-for-iphone-and-osx/ and thought it might do the trick. I got a bunch of ARC error messages, cleaned those out and got this error at runtime:
Detected an attempt to call a symbol in system libraries that is not
present on the iPhone: pthread_cond_init$UNIX2003 called from function
my_thread_init in image oms.
Do i need to use something like ODBC/C?
I know that the solution might be a lengthy one, that's fine. Would be great if someone could at least point me in the right direction.
EDIT:
Since people are keen to know the reason for opting not to use a web service, here it is:
If you're creating an in-house app, the added security of a web service is next to nothing. Working directly with the DB means i need to maintain less code. Plus i don't need to create hacky PHP scripts to get things done.
FINAL CONCLUSION:
I wanted to leave a message for people who're about to do the same thing: Don't :)
Essentially your options are hacky server side scripts or Oracle proprietary mysql client you built yourself (and thus a hacky solution as well). Your choice but i'd strongly advice against it.
This might be the sort of thing that you are looking for:
mysql for iphone and osx
I found it on this iphonedevsdk thread access mysql remote database iphone
Personally I would be only doing this if you really really wanted to.
If you wanted a canned solution, I also found this: Flipper
Or to do it yourself: Build MySql client library for iPhone/iPad
Its not really that hard to find a number of solutions
I needed the same thing (I understand your lecture-pain ;) ) so I wrote this: https://github.com/ciaranj/MySqueakQl it doesn't link to the mysql client libraries so no GPL issues, but it is a very minimal ... very 'fresh' i.e. untested implementation ... just my 2c.
I faced the same problem as you did. I searched and find this.
In http://www.acapela-for-iphone.com/ios-4-2-gm-small-problem-with-simulator
Jean-Michel Reghem Says:
"It seems that Apple changes (again) something into the simulator (as in iOS 4.0)."
Also some people in that page say that this problem didn't show up in device, you can try.
The author has updated his code, and it worked.
Here is the link: http://www.karlkraft.com/index.php/2011/06/07/mysql-for-iphone-and-osx-version-2-0/

How can I help fellow students struggling in programming classes? [closed]

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I'm a computer science student finishing up my second semester of programming classes. I've enjoyed them quite a bit, and learned a lot, but it seems other students are struggling with the concepts and assignments more than I am. When an assignment is due, the inevitable group email comes out the day or two before with people needing some help either with a specific part of the problem, or sometimes people just seem to have a hard time knowing where to start.
I'd really like to be able to help out, but I have a hard time thinking of the right way to give them help without giving them the answer. When I'm having trouble understanding a concept, a code snippet can go along way to helping me, but at the same time if it makes a lot of sense, it can be difficult to think of another way to go about it. Plus the Academic Integrity section of each assignment is always looming overhead warning against sharing code with others. I've tried using pseudo code to help give others an idea on program flow, leaving them to figure out how to implement certain aspects of it, but I didn't get too much feedback and don't know how much it actually helped them out, or if it just confused them further.
So I'm basically looking to see if anyone has experience with this, or good ways that I can help out other students to nudge them in the right direction or help them think about the problem in the right way.
Have them explain their code to you.
This accomplishes several things:
First, it demonstrates that they actually have code to show you. How can they not understand something if they haven't even opened up a text editor yet?
Next, it demonstrates that they understand the code at a basic level. They could have copied it from somewhere. If they don't know the first thing about the code they have, that's a flag. (If they did copy the code, but still took the time to understand the code, then that's still academically dishonest but it's a valuable skill to use after college.)
Finally, now we're at the place where they might actually get it, with your help (or possibly even without!) If they get to the place where the hole in their understanding is (as they're explaining their code to you) and it jumps out at them, then they've solved their own problem. If they don't recognize the hole, then this is where you can give them targeted hints.
I've worked as a TA and at a CS department help desk (and helped buddies). This is what I do...
Abstract out the issue, find a related problem, then work through the related problem with them. If they can't make the connection, you can't really help them.
Edit: and refuse to help with more than the bare basic syntax if they are looking for help the day of or day before. Things should have been dealt with long before deadline. Crutching people on the day-of is not a good practice for you.
Some thoughts:
Do pair programming
Have the student (the person you are helping) sit in the chair and code something. Could be a code snippet, could be a portion of a project, anything, as long as it represents something they have trouble on. As they go, point out (not rudely) places where they may have done something incorrectly, or something that could be improved upon.
Review work done
One of the things that helped me the most was to have a peer (as opposed to a teacher or student aide) review my code. Most of the time the peer could point out places where they might have done something differently.
Make them repeat you.
I often make people I'm helping learn repeat what I just said to see if they understand it or have any questions. You would be surprised how often people don't speak up when they don't understand something.
Offer help before the project is due.
Trying to get the project done the night before it is due is a surefire way to, at the very least, not learn the concepts as thoroughly as you might have otherwise.
Don't code it yourself
Your peers will learn nothing if you do it for them.
Find other resources
An aide, a friendly professor, another one of your peers can be invaluable resources. If you find that your style of teaching doesn't mesh well with one of your peers' style of learning, point them toward someone else who might be able to help them more.
Hope for the best
You can only go so far when teaching someone; they have to want to learn.
One thing that might be helpful to your fellow students is to point to similar code in the lecture notes (or if you don't get lecture notes handed out, in your own notes). That way you're only showing them what the professor said, but doing it in a helpful way.
If another student is open to it, asking them questions about everything they've tried and why would be helpful.
Finally, consider going to your professor and asking for his or her input on what you are allowed to do and how they might suggest you help others. After all, professors have years of experience in teaching students. Even more, will you have an opportunity as an undergraduate to be a TA in future years? I got to TA as an undergraduate, and that helped me to productively use my impulses to assist others without breaking any honor codes. If you have such undergraduate employment opportunities, letting professors see you now as the helpful type will help you acquire them.
I don't think you should be helping them. I think it's academically dishonest. Also, it does them no help to have you give them answers, or even to have you be around to answer questions, since once they get to the exam (or the real world), you won't be there for them. They need to not only learn how to program on their own (which presumably you're helping them do), but also get their questions answered on their own. That means posting on places like StackOverflow. You might want to recommend that they formulate a specific question (always a good exercise) and post it on here with the "homework" tag.
When I was taking CS classes in college, there were a number of students who just couldn't code or design at all (and I'm thinking of a senior level software engineering class in particular). They also had no idea how to go about solving problems, or where to look things up, where to get questions answered, or what questions to ask. They were totally helpless because they had spent most of their undergraduate time working on their homework/projects in groups and having the more talented group members hand-hold them. Don't perpetuate this. The last thing the industry needs is more incompetent programmers who graduate with good grades to put on their resume.
Whenever I tried to teach my girlfriend how to program I did almost nothing but ask questions. (she got to the .each statement before getting bored)
Ask them question how their code works and how they think they could accomplish the task. Give them small nudges in the right direction. And never EVER type something for them. If you have another computer and type code on it to show them and show them the results, that is fine but don't over do that.
Here's the advice I give my student teachers: avoid giving answers to students. Instead, ask them questions. And make sure to ask questions that they can ask themselves in the future. For the material I teach, here are some of the questions I want all students asking themselves:
What is your abstraction?
What is an example of how your abstraction is supposed to behave? Can you show me another example?
Are there any examples of where you abstraction is allowed to fail? How should it fail on that example?
Have you tested these examples?
What is the representation of your abstraction?
How does the representation relate to the abstraction? Can you show me a picture? Can you show me in math?
What functions are allowed to see the representation? What is the contract of each function? Does the representation satisfy an invariant that the function can assume? Does each function make sure the invariant is preserved?
What does valgrind say?
One of the most common problems in teaching is determining whether the student understood you. An easy and effective way to determine if you should continue or rephrase is to have the student demonstrate their understanding by doing something closely related but not identical.
Also, since programming is essentially word problems, it's important that the student break things down into steps. I'd be asking to see their highlevel step-through before I showed them anything. Too many people get hung up in syntax and never really nail down what they're trying to do before diving in.
A general experience in explaining stuff to others is to find out where they stand first. Try to refrain from giving them solutions to problems they don't even have yet (even if you are sure that they will come across them later). In other words, don't go two steps ahead of them. If they have problems understanding call-by-value, don't explain them recursion.
As far as helping fellow students in general, I generally use the "play stupid" approach. I pretend that I know nothing about their particular assignment, and I ask them to get me up to speed on what they are supposed to be doing. I also ask them to give me a quick run-down of what they learned in class about whatever concept the assignment is about. This usually takes about 5 minutes and about 95% of the time, the other student has answered their own question by the time they finish explaining it to me. If they haven't solved it by this point, I ask them to walk me through their solution to the assignment. In doing this, they usually catch where their solution deviates from what they just said they learned in class.
As far as programming-specific help goes, I sometimes ask the other student to send me their code and I run it through a simple shell script I wrote. That script blanks out everything in the code file that is not a comment, and I give the result to the other student to read. The resulting file usually reads like an outline of their code, and a lot of times they can see where their code went wrong simply by getting the code out of the way. If their approach is completely wrong, I tell them to write an outline of what the code is supposed to do (in high-level terms) using comments; after completing this, they fill in each section of the outline with code that implements that outline step (testing each "chunk" as they go). This helps a lot of people separate the code from the algorithm (many common problems I see stem from the lack of a systematic or disciplined approach to problem solving, and this exercise helps get them on the right path).
Another method is to answer questions using a different programming language. For example, I helped several of my fellow students on Matlab projects by explaining the concepts using C, Ruby, or even pseudo-code (that read more like plain English than code). I knew that they had far more experience with other languages, so I used what they knew best to illustrate the concepts and encouraged them to try solving the problem in their "native language" first. Once they were confident that they understood the concepts, they could work on figuring out how to implement them in the target language. Having to learn new concepts while you are still learning a language makes both more difficult. This approach also helps determine whether they are having trouble understanding how to solve the problem or how to code the solution.
PSYCHOLOGICAL APPROACH
show them some popular real world APPLICATIONS (as an example) which they use day to day...written in same programming language you are trying to teach.....
explain every thing with background
give every student, considerable importance
alwaysss use colour coded syntax

What's your Modus Operandi for solving a (programming) problem? [closed]

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While solving any programming problem, what is your modus operandi? How do you fix a problem?
Do you write everything you can about the observable behaviors of the bug or problem?
Take me through the mental checklist of actions you take.
(As they say - First, solve the problem. Then, write the code)
Step away from the computer and grab some paper and a pen or pencil if you prefer.
If I'm around the computer then I try to program a solution right then and there and it normally doesn't work right or it's just crap. Pen and paper force me to think a little more.
First, I go to one bicycle shop; or another.
Once I figure nobody invented that particular bicycle,
Figure out appropriate data structures for the domain and the problem, and then map needed algorithms for dealing with those data structures in ways you need.
Divide and conquer. Solve subsets of the problem
This algorithm has never failed me:
Take Action. Often just sitting there and being terrified or miffed by the problem will not help solve it. Also, often, no amounting of thinking will solve the problem. So you have to get your hands dirty and grapple with the problem head on.
Test. Under exactly what conditions, input values or states, does the problem occur? Make a mental model of why these particular conditions might cause the problem. Check similar conditions that don't cause the problem. Test enough so that you have a clear understanding of the problem.
Visualise. Put debug code in, dump variable contents, single step code whatever. Do anything that clarifies exactly what is going on where - within the problem conditions.
Simplify. Remove or comment code, poke values into variables, run particular functions with certain values. Try your hardest to get to the nub of the problem by cutting away the chaff or stuff that doesn't have a relevance to the problem at hand. Copy code into a separate project and run it, if you have to, to remove dependencies.
Accept. A great man said: "whatever remains, however improbable, must be the truth". In other words, after simplifying as much as you can, whatever is left must be the problem, no matter how bizarre it may seem at first.
Logic. Double, triple check the logic of the problem. Does it make sense? What would have to be true for it to make sense? Is there something you're missing? Is your understanding of the algorithm wrong? If all else fails, re-engineer the problem away.
As an adjunct to step 3, as a last resort, I often employ the binary search method of finding wayward code. Simply comment half the code and see if the problem disappears. If it does then it must be in that half (and vice versa). Half the remaining code and continue.
Google is great for searching for
error messages and common problems. Somewhere, someone has usually encountered your problem before and found a solution.
Pencil and paper. Pseudo Code and
workflow diagrams.
Talk to other developers about it. It
really helps when you have to force
yourself to simplify the problem for
someone else to understand. They may also have another angle. Sometimes it's hard to see the forest through the trees.
Go for a walk. Take your head out of
the problem. Take a step back and try
to see the bigger picture of what you
want to achieve. Make sure the problem you are 'trying' to solve is the one your 'need' to solve.
A big whiteboard is great to work on. Use it to write out workflows and relationships. Talk through what is happening with another team member
Move on. Do something else. Let your subconscious work on the problem. Allow the solution to come to you.
write down the problem
think very hard
write down the answer
I can't believe no one posted this already:
Write up your problem on StackOverflow, and let a bunch of other people solve it for you.
My method, something analytic-sinthetic:
Calm down. Take a deep breath. Focus your attention in what you're going to solve. This may include going for a walk, cleaning the whiteboard, getting scratch paper and pencils ordered, some snacks, etc. Avoid stress.
High level understanding of the problem. In case it is a bug, when does it happened? in what circumstances? If it is a new task, try to diverge of what results are needed. Recollect data, evidence, get acceptance descriptions, maybe documentation or a talk with someone that knows about the issue.
Setup the test playground. Try to feel happy with the tools needed. Use the data collected in the previous step to automate something, hopefully the bug if that's the case, some failing tests otherwise.
Start sinthesizing, summarizing what you know, reflecting that on code. Executing once and once more. If you are not happy with the results, return to step two with renewed ideas, diverge more: maybe apply tools (in order of cost) that helped before, i.e. divide and conquer, debug, multithread, dissassemble, profile, static analysis tools, metrics, etc. Get in this loop until you can isolate the problem and pass the over the phone test.
Now it's time to fix it but you have all the tools set up. It won't be so much trouble. Start writing code, apply refactoring, enjoy describing your solution in the docs.
Get someone to try your solution. She can eventually get you to step 2 but that's ok. Refine your solution and redeploy.
I'm interpreting this as fixing a bug, not a design problem.
Isolate the problem. Does it always occur? Does it occur only the first time run on a set of new data? Does it occur with specific values, but not with others?
Is the system generating any error message that appear related to the problem? Verify that the error messages are not generated when the problem does not occur.
Has anything been changed recently? Those are likely places to start looking.
Identify the gap between what I know is working (e.g. I can start up the app and attempt to do a query) and what I know is not working (e.g. it gives me an error instead of the expected results). Find an intermediate point in the code where it seems possible to look for a problem (does this contain valid data at this point?). This allows me to isolate the problem on one side or the other of the point I looked.
Read the stack traces. If you have a stack trace, find the first line that mentions in-house code. The problem is not in your libraries. Maybe it will turn out to be, but just forget about that possibly first. The error is in your code. It's not a bug in java, it's not a bug in apache commons HTTP client, it's in code written in your organization.
Think. Come up with something the system could be doing that can cause the symptoms you see. Find a way to validate whether that is what the system is doing.
No possibility the bug is in your code? Google for anything you can think of related. Maybe it is a bug in the library, or poor documentation leading you to use it wrong.
Logic.
Break the problem down, use your own brain and knowledge of each component of the system to determine exactly what is happening and why; then on the basis of this you will discover where the problem isn't, and hence determine where it must be.
I stop working on it until tomorrow. I usually solve my problem in the shower the next day. I find stepping away from the issue, and allowing my brain to clear, allows a fresh perspective on the issue.
Answer these three questions in this order:
Q1: What is the desired output?
I don't care if this is a napkin with scribble on it. I want something tangible that shows me what the end result is supposed to look like. If I don't get at least this far then I stop.
Q2: What is the input?
I find out what data I have coming in. Where this data is coming from from. What formulas I may need. What dependencies there might be on A happening before B. What permissions if any are necessary to get this data. I then ask Question 3.
Q3: Is there enough input to create the output?
If the answer is No then I go back to Q2 and get more input from whoever can give it to me.
For very large problems I break them down in Phases and apply Q1 Q2 and Q3 to each phase.
To paraphrase Douglas Adams, programming is easy. You only need to stare at a blank screen until your forehead bleeds. For people who are squeamish about their foreheads, my ideal architect-and-build for the bigger problems would go something like this. (For smaller problems, like George Jempty I can only recommend Feynman's Algorithm.)
What I write is couched in an on-site business setting but there are analogues in open-source or distributed teams. And I can't pretend that every, or even most, projects pan out this way. This is just the series of events that I dream about, and occasionally come to pass.
Get advanced, concise warning of what the problem is likely to look like. This is not the full, final meeting, but an informal discussion. Uncertainty in certain specification details is fine, as long as the client (or manager) is honest. Then take a piece of paper or text editor, and try to condense what you've learned down to five essential points, and then try to condense those to a single sentence. Be happy you can picture the core problem(s) to be solved without referencing any of your documentation.
Think about it for maybe a couple of hours, maybe playing with code and prototyping, but not with a view to the full architecture: you should even do other stuff, if you've time, or go for a walk. It's great if you can learn about a job an hour before home time in order to deliver a decision around midday the next day, so you get to sleep on it. Spend your time looking at potential libraries, frameworks, data standards. Try to tie together at least two languages or resources (say, Javascript on PHP-generated HTML; or get a Python stub talking RPC to a web service). Flesh out the core problems; zoom in on the details; zoom out to make sure the whole shape is still distinct and makes sense.
Send any questions to the client or manager well in advance of a meeting to discuss both the problem and your proposed solution. Invite as many stakeholders and your programming peers along as is convenient (and as your manager is happy with.) Explain the problem back to them, as you see it, then propose your solution. Explain as much as you can; pitch the technical details at your audience, but also let your explanations fill in more details in your own mental model.
Iterate on 2 and 3 until everyone is happy. Happiness is domain-specific. Your industry might require UML diagrams and line-item quotations, or it might be happy with something jotted on a whiteboard with an almost invisible drywipe marker. Make sure everyone has the same expectations of what you're about to build.
When your client or manager is happy for you to start, clear everything. Close Twitter, instant messenger, IRC and email for an hour or two. Start with the overall structure as you see it. Drop some of your prototype code in and see if it feels right. If it doesn't, change the structure as early as possible. But most of all make sure your colleagues give you a couple of hours of space. Try not to fight fires in this time. Begin with a good heart and cheer, and interest in the project. When you're bogged down later on you'll be glad of the clarity that came out of those first few hours.
How your programming proceeds from there depends on what it actually is, and what tasks the finished code needs to perform. And how you ultimately architect your code, and what external resources you use, will always be dictated by your experience, preference and domain knowledge. But give your project and its stakeholder team the most hopeful, most exciting and most engaged start you can.
Pencil, paper and a whiteboard. If you need more organization, use a tool like MindManager.
Andy Hunt's Pragmatic Thinking and Learning has a lot to say on this question.
Question: How do you eat an elephant?
Answer: One bite at a time.
One technique I like using for really big projects is to get into a room with a whiteboard and a pile of square Post-it Notes.
Write your tasks on the Post-it Notes then start sticking them on the whiteboard.
As you go, you can replace tasks that are too big with multiple notes.
You can shift notes around to change the order that the tasks happen in.
Use different colours to indicate different information; I sometimes use a different colour to indicate stuff that we need to do more research on.
This is a great technique for working with a team. Everybody can see the big picture and can contribute in a highly interactive way.
I think about it. I take anywhere from a couple minutes to a few weeks to mull over the problem and develop a general plan of attack.
Hammer out an initial solution. This solution is probably half-baked and one or more aspects may not work.
Refine that solution. Keep working on the problem till i have something that solves the problem.
(and this may be done at any step in the process) Ask questions on stack overflow to clear up any difficulties i'm having at the moment.
One of my ex-colleagues had a unique Modus Operandi. Whenever faced with a hard programming problem (e.g. Knapsack problem or some kind of non-standard optimization problem) he would get stoned on weed, claiming his ability to visualize complex state (such as that of recursive function doing operations on set passed on the stack) was greatly improved. The only difficulty, the next day he could not understand his own code. So eventually I showed him TDD and he has quit smoking...
I write it on a piece of paper and start with my horrible class diagram or flowchart. Then I write it on sticky notes to break it down to "TO DO's".
1 sticky note = 1 task. 1 dumped sticky note = 1 finished task. This works really well for me so far.
Add the problem to StackOverflow, wait about 5-10 minutes and you usually have a brilliant solution! :)
The following applies to a bug rather than building a project from scratch (but even then it could do both if reworded a bit):
Context: What is the problem at hand? What is it preventing, doing wrong, or not doing?
Control: What variables (in the wide sense of the word) are involved? Can the problem be reproduced?
Hypothesise: With enough data on what is occurring or required, it is possible to hypothesise, that is, to draw a mental image of the problem in question.
Evaluate: How much effort, cost, etc, will the correction require? Determine if it's a show stopper or a minor irritant. At this point, it may be too early to tell, but even that is a form of evaluation. This will allow prioritisation.
Plan: How will the problem be approached? Does it require specifications? If so, do them first.
Execute: A.K.A. The fun part.
Test: A.K.A. The not-so-fun-part.
Repeat to satisfaction. Finally:
Feedback: how did it come to be this way? What lead us here? Could this have been prevented, and if so, how?
EDIT:
Really summarised, stop, analyse, act.
Probably a gross oversimplification:
But really, this holds 100% true.
CONCEIVE
What are you without an idea? You may have a problem, but first you must define it more explicitly. You have a frozen pizza that you want to eat. You need to cook that pizza! In programming, this is usually your brainstorming session for coming up with a solution from the hip. Here you decide what your approach is.
PLAN
Well, of course you need to cook that pizza! But HOW! Will you use the oven? No. Too easy. You want to build a solar cooker, so you can eat that frozen pizza anywhere that the sun grants you power to do so. This is your design phase. This is your pencil and paper phase. This is where you start to form a cohesive, step-by-step method to implementation.
EXECUTE
Well, you are going to build a solar oven to cook your frozen pizza; you've decided. NOW DO IT. Write code. Test. Commit. Refactor. Commit.
Related question that may be useful:
Helpful points of view, concepts or ways to think about problems every newbie should know
Every problem I've ever had to solve on a computer has had something to do with solving a task in the real world. Therefore, I've learned to look at how I would accomplish something in the real world and map that to the computer problem.
Example:
I need to keep track of my student's grades and come up with a final grade that is an average of all the grades throughout the year?
Well, I'd save the grades in a log (database) and I'd have a page for every student (Field StudentID) and so on...
I always take a problem to a blog first. Stackoverflow would be a good place to start. Why waste your time re-inventing the wheel when someone else may have already solved a similar problem in the past? If anything you will get some good ideas to solve it yourself.
I use the scientific method:
Based on the available information about the programming problem I come up with a hypothesis about what the reason could be.
Then I design / think up an experiment that will reject or confirm the hypothesis. This could be observing something in a debugger or screen/file output. Or changing the program slightly.
If the hypothesis is rejected then repeat 1. The information gathered in 2. may help in coming up with a new hypothesis.
If the hypothesis is confirmed then the hypothesis may be refined/become more specific (repeat 1.). Or it may already be clear what the problem is.
This directed way of find the problem is much more effective than changing things at random, observe what happens and try to (inappropriately) use statistics.
No one has mentioned truth tables! But that's probably because they're usually only mildly helpful ;) (although your mileage may vary) I used one for the first time yesterday in my 8 years of programming.
Diagramming on whiteboards or paper have always been very helpful for me.
When faced with very weird bugs. Like this: JPA stops working after redeploy in glassfish
I start from scratch. Make a new project. Does it work? Yes. Start to recreate the components of my app one piece of a time. DB. Check. Deploy. Check. Until it breaks. Continue until it breaks. If it never breaks. Ok. You just recreated your entire app. Discard of the old one. When it breaks. You pinpointed the exact problem.
I think - what am i looking for?
What method best solves this problem?
Implement it with solid logic - no code
Pseudo code
code a rough cut
execute
These is my prioritized methods
Analyse
a. Try to find the source of your problem
b. Define desired outcome
c. Brainstorm about solutions
Try on error (If I dont want to analyse)
Google a bit around
a. Of course, look around on stackoverflow
When you get mad, walk away from pc for a cup of coffee
When you still mad after 10 cups of coffee, Go sleep a night to think about the problem
GOLDEN TIP
Never give up. Persistence will always win