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  • Is backing up a MySQL database in GIT a good idea?

    - by wobbily_col
    I am trying to improve the backup situation for my application. I have a Django application and MySQL database. I read an article suggesting backing up the database in Git. On the one hand I like it, as it will keep a copy of the data and the code in synch. But GIT is a designed for code, not for data. As such it will be doing a lot of extra work diffing the mysql dump every commit, which is not really necessary. If I compress the file before storing it, will git diff the files? (The dump file is currently 100MB uncompressed, 5.7Mb when bzipped). Edit: the code and database schema definitions are already in GIT, it is really the data I am concerned about backing up now.

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  • Reading graph inputs for a programming puzzle and then solving it

    - by Vrashabh
    I just took a programming competition question and I absolutely bombed it. I had trouble right at the beginning itself from reading the input set. The question was basically a variant of this puzzle http://codercharts.com/puzzle/evacuation-plan but also had an hour component in the first line(say 3 hours after start of evacuation). It reads like this This puzzle is a tribute to all the people who suffered from the earthquake in Japan. The goal of this puzzle is, given a network of road and locations, to determine the maximum number of people that can be evacuated. The people must be evacuated from evacuation points to rescue points. The list of road and the number of people they can carry per hour is provided. Input Specifications Your program must accept one and only one command line argument: the input file. The input file is formatted as follows: the first line contains 4 integers n r s t n is the number of locations (each location is given by a number from 0 to n-1) r is the number of roads s is the number of locations to be evacuated from (evacuation points) t is the number of locations where people must be evacuated to (rescue points) the second line contains s integers giving the locations of the evacuation points the third line contains t integers giving the locations of the rescue points the r following lines contain to the road definitions. Each road is defined by 3 integers l1 l2 width where l1 and l2 are the locations connected by the road (roads are one-way) and width is the number of people per hour that can fit on the road Now look at the sample input set 5 5 1 2 3 0 3 4 0 1 10 0 2 5 1 2 4 1 3 5 2 4 10 The 3 in the first line is the additional component and is defined as the number of hours since the resuce has started which is 3 in this case. Now my solution was to use Dijisktras algorithm to find the shortest path between each of the rescue and evac nodes. Now my problem started with how to read the input set. I read the first line in python and stored the values in variables. But then I did not know how to store the values of the distance between the nodes and what DS to use and how to input it to say a standard implementation of dijikstras algorithm. So my question is two fold 1.) How do I take the input of such problems? - I have faced this problem in quite a few competitions recently and I hope I can get a simple code snippet or an explanation in java or python to read the data input set in such a way that I can input it as a graph to graph algorithms like dijikstra and floyd/warshall. Also a solution to the above problem would also help. 2.) How to solve this puzzle? My algorithm was: Find shortest path between evac points (in the above example it is 14 from 0 to 3) Multiply it by number of hours to get maximal number of saves Also the answer given for the variant for the input set was 24 which I dont understand. Can someone explain that also. UPDATE: I get how the answer is 14 in the given problem link - it seems to be just the shortest path between node 0 and 3. But with the 3 hour component how is the answer 24 UPDATE I get how it is 24 - its a complete graph traversal at every hour and this is how I solve it Hour 1 Node 0 to Node 1 - 10 people Node 0 to Node 2- 5 people TotalRescueCount=0 Node 1=10 Node 2= 5 Hour 2 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5(Rescued) Node 0 to Node 1 = 10 Node 0 to Node 2 = 5 Node 1 to Node 2 = 4 TotalRescueCount = 10 Node 1 = 10 Node 2= 5+4 = 9 Hour 3 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5+4 = 9(Rescued) TotalRescueCount = 9+5+10 = 24 It hard enough for this case , for multiple evac and rescue points how in the world would I write a pgm for this ?

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  • Exclude PHP from output from WYSIWYG in CMS

    - by bytewalls
    I'm writing a basic CMS for one of my sites and have run into an issue where some pages need to dynamically serve PHP and JS, where as others are plain HTMl. I want there to be a setting which will allow this for the pages that need it and will load ACE editor instead of a different wysiwyg editor. The challenge here is that on the pages which I do not explicitly tell it there will be code, I want to reject any inputs that code. I can set it up to insert a for all pages without JS, but how can I keep php code from running?

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  • Content of AUTHORS file

    - by user14284
    GNU recommend make AUTHORS file for list of authors and contributos of a program. But how many "levels" of authors and contributors should contain the file? E.g. I write a program foo, that actively use some library. Should I include authors of the library in the AUTHORS? It seems to yes, because total code of foo contain code from library. But if yes, I should include also authors of all others libraries, including standard libraries of compiler, authors of the compiler and other tools for producing final executable code, authors of OS... When I should stop?

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  • Good way to extract strings to resource

    - by Bart Friederichs
    I am using Visual Studio 2010 and we just decided to get started on localization of our code. We want to use the per-form resource file in combination with a separate resource file for static strings, called strings.resx. I was wondering if there is a good way to extra static strings (we already have quite some code we need to translate) to the strings.resx file? I have tried this plugin: Resource Refactoring 2010, but it doesn't work completely. It creates the correct new resource, but the strings aren't refactored in the code. Also, the tool seems to be abandoned by its developer. Is there a good plugin that can do this?

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  • design for interruptable operations

    - by tpaksu
    I couldn't find a better topic but here it is; 1) When user clicks a button, code starts t work, 2) When another button is clicked, it would stop doing whatever it does and start to run the second button's code, 3) Or with not user interaction, an electrical power down detected from a connected device, so our software would cancel the current event and start doing the power down procedure. How is this design mostly applied to code? I mean "stop what you are doing" part? If you would say events, event handlers etc. how do you bind a condition to the event? and how do you tell the program without using laddered if's to end it's process? method1(); if (powerdown) return; method2(); if (powerdown) return; etc.

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  • Why is 0 false?

    - by Morwenn
    This question may sound dumb, but why does 0 evaluates to false and any other [integer] value to true is most of programming languages? String comparison Since the question seems a little bit too simple, I will explain myself a little bit more: first of all, it may seem evident to any programmer, but why wouldn't there be a programming language - there may actually be, but not any I used - where 0 evaluates to true and all the other [integer] values to false? That one remark may seem random, but I have a few examples where it may have been a good idea. First of all, let's take the example of strings three-way comparison, I will take C's strcmp as example: any programmer trying C as his first language may be tempted to write the following code: if (strcmp(str1, str2)) { // Do something... } Since strcmp returns 0 which evaluates to false when the strings are equal, what the beginning programmer tried to do fails miserably and he generally does not understand why at first. Had 0 evaluated to true instead, this function could have been used in its most simple expression - the one above - when comparing for equality, and the proper checks for -1 and 1 would have been done only when needed. We would have considered the return type as bool (in our minds I mean) most of the time. Moreover, let's introduce a new type, sign, that just takes values -1, 0 and 1. That can be pretty handy. Imagine there is a spaceship operator in C++ and we want it for std::string (well, there already is the compare function, but spaceship operator is more fun). The declaration would currently be the following one: sign operator<=>(const std::string& lhs, const std::string& rhs); Had 0 been evaluated to true, the spaceship operator wouldn't even exist, and we could have declared operator== that way: sign operator==(const std::string& lhs, const std::string& rhs); This operator== would have handled three-way comparison at once, and could still be used to perform the following check while still being able to check which string is lexicographically superior to the other when needed: if (str1 == str2) { // Do something... } Old errors handling We now have exceptions, so this part only applies to the old languages where no such thing exist (C for example). If we look at C's standard library (and POSIX one too), we can see for sure that maaaaany functions return 0 when successful and any integer otherwise. I have sadly seen some people do this kind of things: #define TRUE 0 // ... if (some_function() == TRUE) { // Here, TRUE would mean success... // Do something } If we think about how we think in programming, we often have the following reasoning pattern: Do something Did it work? Yes -> That's ok, one case to handle No -> Why? Many cases to handle If we think about it again, it would have made sense to put the only neutral value, 0, to yes (and that's how C's functions work), while all the other values can be there to solve the many cases of the no. However, in all the programming languages I know (except maybe some experimental esotheric languages), that yes evaluates to false in an if condition, while all the no cases evaluate to true. There are many situations when "it works" represents one case while "it does not work" represents many probable causes. If we think about it that way, having 0 evaluate to true and the rest to false would have made much more sense. Conclusion My conclusion is essentially my original question: why did we design languages where 0 is false and the other values are true, taking in account my few examples above and maybe some more I did not think of? Follow-up: It's nice to see there are many answers with many ideas and as many possible reasons for it to be like that. I love how passionate you seem to be about it. I originaly asked this question out of boredom, but since you seem so passionate, I decided to go a little further and ask about the rationale behind the Boolean choice for 0 and 1 on Math.SE :)

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  • for vs. foreach vs. LINQ

    - by beccoblu
    When I write code in Visual Studio, ReSharper (God bless it!) often suggests me to change my old-school for loop in the more compact foreach form. And often, when I accept this change, ReSharper goes a step forward, and suggests me to change it again, in a shiny LINQ form. So, I wonder: are there some real advantages, in these improvements? In pretty simple code execution, I cannot see any speed boost (obviously), but I can see the code becoming less and less readable... So I wonder: is it worth it?

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  • How to solve programming problems using logic? [closed]

    - by md nth
    I know these principles: Define the constrains and operations,eg constrains are the rules that you cant pass and what you want determined by the end goal, operations are actions you can do, "choices" . Buy some time by solving easy and solvable piece. Halving the difficulty by dividing the project into small goals and blocks. The more blocks you create the more hinges you have. Analogies which means : using other code blocks, yours or from other programmers . which has problem similar to the current problem. Experiments not guessing by writing "predicted end" code, in other word creating a hypothesis, about what will happen if you do this or that. Use your tools first, don't begin with a unknown code first. By making small goals you ll not get frustrated. Start from smallest problem. Are there other principles?

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  • Difficult to replicate objects (object Customer) on the list? [migrated]

    - by gandolf
    I wrote a program that does work with files like delete and update, store, and search And all customers But I have a problem with the method is LoadAll Once the data are read from the file and then Deserialize the object becomes But when I want to save the list of objects in the list are repeated. How can I prevent the duplication in this code? var customerStr = File.ReadAllLines (address); The code is written in CustomerDataAccess class DataAccess Layer. Project File The main problem with the method LoadAll Code: public ICollection<Customer> LoadAll() { var alldata = File.ReadAllLines(address); List<Customer> lst = new List<Customer>(); foreach (var s in alldata) { var objCustomer = customerSerializer.Deserialize(s); lst.Add(objCustomer); } return lst; }

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  • find substring and indices in mips

    - by ccc
    im trying find out substring and first occurrence indices. but something wrong. im comparing each element of pattern array and each element of string array until pointer reach to '\0'. and if any characater found it keep in temp array. and increasing pointers +1. whats the problem. algorithm is totaly wrong ? #Note: $v0 is a symbolic name used by the assember for $2. # $a0 is a symbolic name used by the assember for $4. .data prompt_str: .asciiz "Please type a text string: " prompt_ptr: .asciiz "Please type a pattern string: " print_yes: .asciiz "Yes, there is a match." print_no: .asciiz "No, there is no match." text_str: .asciiz "Text string : " pattern_str: .asciiz "Pattern string : " print_out: .asciiz "Output to be produced :" print_dash: .asciiz "----------------------" print_index: .asciiz "Starting index :" print_msg : .asciiz "Length of longest partial match = " nl: .asciiz "\n" str : .space 81 ptr : .space 81 tmp : .space 81 .text main: la $a0, prompt_str li $v0, 4 #print_string command. syscall la $a0,str #read string li $a1,81 li $v0,8 syscall la $t0,str #move string to $t0 la $a0,prompt_ptr li $v0,4 #print pattern command syscall la $a0,ptr #read pattern li $a1,81 li $v0,8 syscall la $t1,ptr #move pattern to $t1 la $t5,tmp #move temp to $t5 lb $t2,0($t0) #pointer first element array of string lb $t3,0($t1) #pointer first element array of pattern lb $t6,0($t5) #pointer first element array of temp loop : beq $t3,$0,end_loop beq $t2,$t3,match addiu $t0,$t0,1 j loop match : move $t6,$t2 addiu $t5,$t5,1 addiu $t0,$t0,1 addiu $t1,$t1,1 j print_match print_match : la $a0,text_str #print string li $v0,4 syscall move $a0,$t0 li $v0,4 syscall la $a0,nl #print newline character li $v0,4 syscall la $a0,pattern_str #print pattern string li $v0,4 syscall move $a0,$t1 li $v0,4 syscall la $a0,nl #print newline character li $v0,4 syscall la $a0,print_out #print output line and newline character li $v0,4 syscall la $a0,nl li $v0,4 syscall la $a0,print_dash li $v0,4 syscall la $a0,print_yes li $v0,4 syscall la $a0,print_index #print starting index li $v0,4 syscall li $v0,10 syscall end_loop : li $v0,10 syscall

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  • SSRS 2005 - Cascading parameters and default value update problem

    - by sHr0oMaN
    I have a report with cascading parameters. The first parameter is Finanical Period Type, being either Month or Week. The second parameter is a list of either financial months or weeks depending on what was selected for the first parameter. This all works well and selecting a series of different Financial Period Types in sequence correctly updates the second parameter's values. However I now wish to add a default value for the second parameter, which is once again dependent on the first parameter. So I've added an additional field to the dataset populating the second parameter called DefaultPeriod and set the second parameter's default value to be retrieved from the above field. The first time I select the Financial Period Type, the default is correctly set. However changing the Financial Period Type results in an updated list for the second parameter, but the default is incorrect. It remains set to the original default value, even thought the dataset has been refresh and the DefaultPeriod field is correct. This is both an issue in the IDE and on the Report Manager site.

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  • UINavigationController inside tabbar loading a child root view

    - by Doug
    Hi guys, Firstly i'll preface by saying that i am a complete Cocoa touch/objective c noob (.Net dev having a dabble) I have searched on Google as well as here but cannot seem to find an easy solution. I have a UItabbarcontroller view with a UINavigationController inside its first tab I have the root view for this UINavigationController stored in a seperate class and NIB as i am trying to seperate the data viewing from the data loading (i'm going to reuse the table list in multiple places in my database) and simply pass the root view its data using a loading method and have it take it from there. What i want to happen: App loads and loads the first view of the tab bar (A UINavigationController) The UINavigationController inside the first view loads a root view (a UIViewController with a table view) and sets its title The UINavigationController loads the data from a web service and parses it The UINavigationController sends the data to a loading method inside the UIViewController Am i thinking about this completely wrongly? What currently happens: the first tab bar loads with an empty uinavigationcontroller (no table view) the data methods fire and get the webservice data this child view gets sent its data using the loading method the tableview delegate events fail to fire inside the child view telling it to load the data into the table I just can't seem how to load my second view inside the root view of the navigation controller and then send it my data?

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  • How to call RequiredFieldValidator on client before postback

    - by Si
    I've inherited some code which breaks a page up into tabs using divs. On the first page there are many required field and regex validators. The problem is a user can switch to another tab, trigger a postback and fail the validators on the first page, leaving things in a mess. What I want to be able to do is perform the validation on the first page as a user selects another tab, thus preventing them from moving to a new tab until the first page is valid. <ul> <li><a href="#tab1">Tab 1</a> </li> <li><a href="#tab2" onclick="return isValid();">Tab 2</a></li> <li><a href="#tab3" onclick="return isValid();">Tab 3</a></li> </ul> Where isValid needs to fire off the validators. Thanks!

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  • jQuery .each() with multiple selectors - skip, then .empty() elements

    - by joe
    I'd like to remove all matching elements, but skip the first instance of each match: // Works as expected: removes all but first instance of .a jQuery ('.a', '#scope') .each ( function (i) { if (i > 0) jQuery (this).empty(); }); // Expected: removal of all but first instance of .a and .b // Result: removal of *all* instances of both .a and .b jQuery ('.a, .b', '#scope') .each ( function (i) { if (i > 1) jQuery (this).empty(); }); <div id="scope"> <!-- Want to keep the first instance of .a and .b --> <div class="a">[bla]</span> <div class="b">[bla]</span> <!-- Want to remove all the others --> <div class="a">[bla]</span> <div class="b">[bla]</span <div class="a">[bla]</span> <div class="b">[bla]</span ... </div> Any suggestions? Using jQuery() rather than $() because of conflict with 'legacy' code Using .empty() because .a contains JS I'd like to disable Stuck with jQuery 1.2.3 Thanks you!

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  • solve a classic map-reduce problem with opencl?

    - by liuliu
    I am trying to parallel a classic map-reduce problem (which can parallel well with MPI) with OpenCL, namely, the AMD implementation. But the result bothers me. Let me brief about the problem first. There are two type of data that flow into the system: the feature set (30 parameters for each) and the sample set (9000+ dimensions for each). It is a classic map-reduce problem in the sense that I need to calculate the score of every feature on every sample (Map). And then, sum up the overall score for every feature (Reduce). There are around 10k features and 30k samples. I tried different ways to solve the problem. First, I tried to decompose the problem by features. The problem is that the score calculation consists of random memory access (pick some of the 9000+ dimensions and do plus/subtraction calculations). Since I cannot coalesce memory access, it costs. Then, I tried to decompose the problem by samples. The problem is that to sum up overall score, all threads are competing for few score variables. It keeps overwriting the score which turns out to be incorrect. (I cannot carry out individual score first and sum up later because it requires 10k * 30k * 4 bytes). The first method I tried gives me the same performance on i7 860 CPU with 8 threads. However, I don't think the problem is unsolvable: it is remarkably similar to ray tracing problem (for which you carry out calculation that millions of rays against millions of triangles). Any ideas?

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  • Algorithm to get through a maze

    - by Sam
    Hello, We are currently programming a game (its a pretty unknown language: modula 2), And the problem we encountered is the following: we have a maze (not a perfect maze) in a 17 x 12 grid. The computer has to generate a way from the starting point (9, 12) to the end point (9, 1). I found some algorithms but they dont work when the robot has to go back: xxxxx x => x x xxx or: xxxxx x xxxxxx x x x x x xxxxxx x => x xxxxxxxxx I found a solution for the first example type but then the second type couldn't be solved and the solution I made up for the second type would cause the robot to get stuck in the first type of situation. It's a lot of code so i'll give the idea: WHILE (end destination not reached) DO { try to go right, if nothing blocks you: go right if you encounter a block, try up until you can go right, if you cant go up anymore try going down until you can go right, (starting from the place you first were blocked), if you cant go down anymore, try one step left and fill the spaces you tested with blocks. } This works for the first type of problem ... not for the second one. Now it could be that i started wrong so i am open for better algorithms or solutions specificaly to how i could improve my algorithm. Thanks a lot!!

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  • SQL Server slow in production environment

    - by Lieven Cardoen
    I have a weird problem in a customer's production environment. I can't give any details on the infrastructure, except that SQL server runs on a virtual server. The data, log and filestream file are on another storage server (data and filestream together and log on a separate server). In our local Test environment, there's one particular query that executes with these durations: first we clear the cache 300ms (First time it takes longer, but from then on it's cached.) 20ms 15ms 17ms In the customer's production environment, the SQL Server is more powerful, these are the durations (I didn't have the rights to clear the cache. Will try this tomorrow). 2500ms 2600ms 2400ms The servers in the customer's production environment are more powerful but they do have virtual servers (we don't). What could be the cause... Not enough memory? Fragmentation? Physical storage? How would you tackle this performance problem? EDIT: Some people have asked me if the data set is equal and it is. I restored their database on our environment. It's true that this was the first thing I looked at. (@Everyone: I added the edit because it will be the first thing that many will think off).

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  • Threading best practice when using SFTP in C#

    - by Christian
    Ok, this is more one of these "conceptual questions", but I hope I got some pointers in the right direction. First the desired scenario: I want to query an SFTP server for directory and file lists I want to upload or download files simulaneously Both things are pretty easy using a SFTP class provided by Tamir.SharpSsh, but if I only use one thread, it is kind of slow. Especially the recursion into subdirs gets very "UI blocking", because we are talking about 10.000 of directories. My basic approach is simple, create some kind of "pool" where I keep 10 open SFTP connections. Then query the first worker for a list of dirs. If this list was obtained, send the next free workers (e.g. 1-10, first one is also free again) to get the subdirectory details. As soon as there is a worker free, send him for the subsubdirs. And so on... I know the ThreadPool, simple Threads and did some Tests. What confuses me a little bit is the following: I basically need... A list of threads I create, say 10 Connect all threads to the server If a connection drops, create a new thread / sftp client If there is work to do, take the first free thread and handle the work I am currently not sure about the implementation details, especially the "work to do" and the "maintain list of threads" parts. Is it a good idea to: Enclose the work in an object, containing a job description (path) and a callback Send the threads into an infinite loop with 100ms wait to wait for work If SFTP is dead, either revive it, or kill the whole thread and create a new one How to encapsulate this, do I write my own "10ThreadsManager" or are there some out Ok, so far... Btw, I could also use PRISM events and commands, but I think the problem is unrelated. Perhaps the EventModel to signal a done processing of a "work package"... Thanks for any ideas, critic.. Chris

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  • Selector and Iterating Through a Table Within a Div

    - by GregH
    I have been working on this and cannot get this iterator to work. I have the following HTML and am trying to iterate through all rows (except the first row) and extract the values in cells (td) 2 and 3 : <div id="statsId"> <table width="220" cellspacing="0" cellpadding="0" border="0"> <tbody> <tr> <td width="65"/> <td width="90"/> <td width="65"/> </tr> <tr style="font-weight: bold;"> <td align="left">$1.00</td> <td> <a href="#">UserID1</a> </td> <td>Single</td> </tr> <tr> <td align="left">$6.99</td> <td> <a href="#">UserID2</a> </td> <td>Multiple</td> </tr> <tr>... .....(snip) I tried the following iterator to iterate through all except the first row of the table that is a child of "div#statsID" and get the values of the 2nd and 3rd cells (in the example, the first extracted cells would have values of "UserID1" and "Single"), but it doesn't work. $('div#statsId > table tr:not(:nth-child(1))').each(function(i, ele) { var secondCol = $('td:nth-child(2)', ele).innerHTML var thirdCol= $('td:nth-child(3)', ele).text() ..... }); Any suggestions on how to specify and iterate through the rows (except the first) of a table that is a child of a div would be appreciated.

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  • Designing a fluid Javascript interface to abstract away the asynchronous nature of AJAX

    - by Anurag
    How would I design an API to hide the asynchronous nature of AJAX and HTTP requests, or basically delay it to provide a fluid interface. To show an example from Twitter's new Anywhere API: // get @ded's first 20 statuses, filter only the tweets that // mention photography, and render each into an HTML element T.User.find('ded').timeline().first(20).filter(filterer).each(function(status) { $('div#tweets').append('<p>' + status.text + '</p>'); }); function filterer(status) { return status.text.match(/photography/); } vs this (asynchronous nature of each call is clearly visible) T.User.find('ded', function(user) { user.timeline(function(statuses) { statuses.first(20).filter(filterer).each(function(status) { $('div#tweets').append('<p>' + status.text + '</p>'); }); }); }); It finds the user, gets their tweet timeline, filters only the first 20 tweets, applies a custom filter, and ultimately uses the callback function to process each tweet. I am guessing that a well designed API like this should work like a query builder (think ORMs) where each function call builds the query (HTTP URL in this case), until it hits a looping function such as each/map/etc., the HTTP call is made and the passed in function becomes the callback. An easy development route would be to make each AJAX call synchronous, but that's probably not the best solution. I am interested in figuring out a way to make it asynchronous, and still hide the asynchronous nature of AJAX.

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  • Good ways to dynamically generate the start image of an iPhone/iPad app

    - by Dr Dork
    I'm self-learning iPhone development and I see that one of the aspects of an iPhone/iPad app is the start image that gets displayed when your app is run. I'd like my start image to display some basic info about the user when the app is launched, but that info has to first be collected by the user when the app is first run. That tells me that I either need to dynamically generate the start image after the user enters their information or I need to place a label of some sort on top of my static start image in order to accomplish this. The first time the app launched and before the user enters their info, the start image can be anything or nothing at all, I'm not concerned about this. So, my two questions are this... Can you place controls, like a label, on top of the start image when your app is launched? If not, what's a good approach to dynamically generating the start image after the app is launched for the first time and the user info is collected? Thanks so much in advance for your help! I'm going to begin researching this question right now.

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  • Maths Question: number of different permutations

    - by KingCong
    This is more of a maths question than programming but I figure a lot of people here are pretty good at maths! :) My question is: Given a 9 x 9 grid (81 cells) that must contain the numbers 1 to 9 each exactly 9 times, how many different grids can be produced. The order of the numbers doesn't matter, for example the first row could contain nine 1's etc. This is related to Sudoku and we know the number of valid Sudoku grids is 6.67×10^21, so since my problem isn't constrained like Sudoku by having to have each of the 9 numbers in each row, column and box then the answer should be greater than 6.67×10^21. My first thought was that the answer is 81! however on further reflection this assume that the 81 number possible for each cell are different, distinct number. They are not, there are 81 possible numbers for each cell but only 9 possible different numbers. My next thought was then that each of the cells in the first row can be any number between 1 and 9. If by chance the first row happened to be all the same number, say all 1s, then each cell in the second row could only have 8 possibilites, 2-9. If this continued down until the last row then number of different permutations could be calculated by 9^2 * 8^2 * 7^2 ..... * 1^2. However this doesn't work if each row doesn't contain 9 of the same number. It's been quite a while since I studied this stuff and I can't think of a way to work it out, I'd appreciate any help anyone can offer.

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  • Getting Vars to bind properly across multiple files

    - by Alex Baranosky
    I am just learning Clojure and am having trouble moving my code into different files. I keep detting this error from the appnrunner.clj - Exception in thread "main" java.lang.Exception: Unable to resolve symbol: -run-application in this context It seems to be finding the namespaces fine, but then not seeing the Vars as being bound... Any idea how to fix this? Here's my code: APPLICATION RUNNER - (ns src/apprunner (:use src/functions)) (def input-files [(resource-path "a.txt") (resource-path "b.txt") (resource-path "c.txt")]) (def output-file (resource-path "output.txt")) (defn run-application [] (sort-files input-files output-file)) (-run-application) APPLICATION FUNCTIONS - (ns src/functions (:use clojure.contrib.duck-streams)) (defn flatten [x] (let [s? #(instance? clojure.lang.Sequential %)] (filter (complement s?) (tree-seq s? seq x)))) (defn resource-path [file] (str "C:/Users/Alex and Paula/Documents/SoftwareProjects/MyClojureApp/resources/" file)) (defn split2 [str delim] (seq (.split str delim))) (defstruct person :first-name :last-name) (defn read-file-content [file] (apply str (interpose "\n" (read-lines file)))) (defn person-from-line [line] (let [sections (split2 line " ")] (struct person (first sections) (second sections)))) (defn formatted-for-display [person] (str (:first-name person) (.toUpperCase " ") (:last-name person))) (defn sort-by-keys [struct-map keys] (sort-by #(vec (map % [keys])) struct-map)) (defn formatted-output [persons output-number] (let [heading (str "Output #" output-number "\n") sorted-persons-for-output (apply str (interpose "\n" (map formatted-for-display (sort-by-keys persons (:first-name :last-name)))))] (str heading sorted-persons-for-output))) (defn read-persons-from [file] (let [lines (read-lines file)] (map person-from-line lines))) (defn write-persons-to [file persons] (dotimes [i 3] (append-spit file (formatted-output persons (+ 1 i))))) (defn sort-files [input-files output-file] (let [persons (flatten (map read-persons-from input-files))] (write-persons-to output-file persons)))

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  • GAE Task Queue oddness

    - by b3nw
    I have been testing the taskqueue with mixed success. Currently I am using the default queue, in default settings ect ect.... I have a test url setup which inserts about 8 tasks into the queue. With short order, all 8 are completed properly. So far so good. The problem comes up when I re-load that url twice under say a minute. Now watching the task queue, all the tasks are added properly, but only the first batch execute it seems. But the "Run in Last Minute" # shows the right number of tasks being run.... The request logs tell a different story. They show only the first set of 8 running, but all task creation urls working successfully. The oddness of this is that if I wait say a minute between the task creation url requests, it will work fine. Oddly enough changing the bucket_size or execution speed does not seem to help. Only the first batch are executed. I have also reduced the number of requests all the way down to 2, and still found only the first 2 execute. Any others added display the same issues as above. Any suggestions? Thanks

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