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  • algorithm - How to sort a 0/1 array with 2n/3 comparisons?

    - by Jackson Tale
    In Algorithm Design Manual, there is such an excise 4-26 Consider the problem of sorting a sequence of n 0’s and 1’s using comparisons. For each comparison of two values x and y, the algorithm learns which of x < y, x = y, or x y holds. (a) Give an algorithm to sort in n - 1 comparisons in the worst case. Show that your algorithm is optimal. (b) Give an algorithm to sort in 2n/3 comparisons in the average case (assuming each of the n inputs is 0 or 1 with equal probability). Show that your algorithm is optimal. For (a), I think it is fairly easy. I can choose a[n-1] as pivot, then do something like in quicksort partition, scan 0 to n - 2, find the middle point where left side is all 0 and right side is all 1, this take n - 1 comparisons. But for (b), I can't get a clue. It says "each of the n inputs is 0 or 1 with equal probability", so I guess I can assume the numbers of 0 and 1 equal? But how can I get a result which is related to 1/3? divide the whole array into 3 groups? Thanks

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  • Linq Query - Average Time (DateTime data types)

    - by Jade
    I have a database that has the following records in a DateTime field: 2012-04-13 08:31:00.000 2012-04-12 07:53:00.000 2012-04-11 07:59:00.000 2012-04-10 08:16:00.000 2012-04-09 15:11:00.000 2012-04-08 08:28:00.000 2012-04-06 08:26:00.000 I want to run a linq to sql query to get the average time from the records above. I tried the following: (From o In MYDATA Select o.SleepTo).Average() Since "SleepTo" is a datetime field I get an error on Average(). If I was trying to get the average of say an integer, the above linq query works. What do I need to do to get it to work for datetimes?

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  • jquery.ui.tabs.js doesn't load tab data in IE9, Chrome - works perfectly fine in firefox

    - by Salma Khan
    I have few issues that I am facing on my site and I have no idea how to fix those. Please go to http://link.zambeel.ca/index.php/component/obituary/detail/52 and click on Photos tab, it doesn't load images promptly in IE9 and Chrome. I have made it work in firefox with the following code: var loadNextTab = function() { if (indexesToLoad.length == 0) return; var index = indexesToLoad.shift(); $("#tabs-1").tabs("load",index); }; $("#tabs-1").tabs({ cache: true, load: loadNextTab }); Please help me resolve this matter as soon as possible. Just to let you guys know, I am not a programmer by any means.

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  • Async data loading with WCF service with UI capabilities

    - by Jojo
    I'm working on complex user control(with Telerik components). I'm trying to implement following functionality: Typing some text in RadTextBox(let say: "Hello.txt"). Clicking on Button "Check". onClientClick for button "Check" will call WCF method with parameters. Let say that this request/response will take more that 10 seconds, meanwhile I'll see loading image near TextBox AND the most important, I can continue to work on other fields. When WCF service responses UI will be updated with the result. Thanks in advance

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  • How to duplicate INSERTS into a seperate table?

    - by Ash
    An iPhone application I have installed uses an SQLite database to log entries with basic INSERTS and DELETES being performed on it. However I wish to keep a permanent log of the INSERTS made to this table, so when an INSERT occurs, I want it to be written to another table also as to create a log. I don't have access to the application source code in order to modify the SQL statements made, I do have access to the SQLite database. Can I do this with triggers? If so can somebody provide a short example.

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  • Convert.ToSingle() for float data Type

    - by Asim Sajjad
    I have used many of the Convert.To..... functions for conversion , but I didn't understand one thing that for every datatype they have provide a Convert.To function but not for float datatype, in order to convert to float you need to use Convert.ToSingle() , why is this so ?

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  • HTML forms and passing data back

    - by coLOLtip
    My html form is spreading over several pages (steps), and I want to let the use to take step back in case they would like to change something they filled in. So, I don't want to make users re-type all the information they already have typed once. Thus, how would I make it so that all the information would go back, to speak so? (I use PHP on server-side.)

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  • CoreData is saving model without the save: method being called

    - by chris
    I have a list of items with a plus button in the navigation bar that opens up a modal window containing a table of the models attributes, that displays a form when the table items are clicked (pretty standard form style). For some reason if I click the plus button to open the form to create a new model, then immediately click the done button, the person model is saved. The action linked to the done button does nothing but call on a delegate method notifying the personListViewController to close the window. The apple docs do state that the model is not saved after calling the insertNewObjectForEntityName: ... Simply creating a managed object does not cause it to be saved to a persistent store. The managed object context acts as a scratchpad. I am at a lost to why this is happening, but every time I click the done button I have a new blank item in the original tableView. I am using SDK v3.1.3 // PersonListViewController - open modal window - (void)addPerson { // Load the new form PersonNewViewController *newController = [[PersonNewViewController alloc] init]; newController.modalFormDelegate = self; [self presentModalViewController:newController animated:YES]; [newController release]; } // PersonFormViewController - (void)viewDidLoad { [super viewDidLoad]; if ( person == nil ) { MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; self.person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:appDelegate.managedObjectContext]; } ... UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(done)]; self.navigationItem.rightBarButtonItem = doneButton; [doneButton release]; } - (IBAction) done { [self.modalFormDelegate didCancel]; } // delegate method in the original listViewController - (void) didCancel { [self dismissModalViewControllerAnimated:YES]; }

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  • How do I remove the leaves of a binary tree?

    - by flopex
    I'm trying to remove all of the leaves. I know that leaves have no children, this is what I have so far. public void removeLeaves(BinaryTree n){ if (n.left == null && n.right == null){ n = null; } if (n.left != null) removeLeaves(n.left); if (n.right != null) removeLeaves(n.right); }

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  • What techniques are available for filtering collections of objects when using zodb?

    - by Omega
    As the title says: What techniques are available for filtering objects when using zodb? The equivalent in SQL terms would be something like filtering results by a date range. Or only returning rows with a particular value set in a column. If I had a series of blog posts and only wanted ones done in the past month, what would I have to do? Is there any way to optimize these kinds of "queries"? My gut tells me iterating over all the objects in a relationship simply to perform a test is less than optimal.

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  • Re-load Android activity data

    - by rhinds
    Hi, I am writing an Android app, part of which will be a survey involving multiple pages of checkbox question and answers. I have created an activity to display the question and options (from the DB) and what I want to do now is when i press the "Next" button it should just reload the current activity with the next question set from the database. (the activity starts with survey.getNextQuestion() - so its just a case of refreshing the activity so it updates) Im sure this is a simple thing to do -any ideas? Thanks

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  • MATLAB: draw centroids

    - by Myx
    Hello - my main question is given a feature centroid, how can I draw it in MATLAB? In more detail, I have an NxNx3 image (an rgb image) of which I take 4x4 blocks and compute a 6-dimensional feature vector for each block. I store these feature vectors in an Mx6 matrix on which I run kmeans function and obtain the centroids in a kx6 matrix, where k is the number of clusters and 6 is the number of features for each block. How can I draw these center clusters in my image in order to visualize if the algorithm is performing the way I wish it to perform? Or if anyone has any other way/suggestions on how I can visualize the centroids on my image, I'd greatly appreciate it. Thank you.

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  • OpenGL index buffer object with additional data

    - by muksie
    I have a large set of lines, which I render from a vertex buffer object using glMultiDrawArrays(GL_LINE_STRIP, ...); This works perfectly well. Now I have lots of vertex pairs which I also have to visualize. Every pair consists of two vertices on two different lines, and the distance between the vertices is small. However, I like to have the ability to draw a line between all vertex pairs with a distance less than a certain value. What I like to have is something like a buffer object with the following structure: i1, j1, r1, i2, j2, r2, i3, j3, r3, ... where the i's and j's are indices pointing to vertices and the r's are the distances between those vertices. Thus every vertex pair is stored as a (i, j, r) tuple. Then I like to have a (vertex) shader which only draws the vertex pairs with r < SOME_VALUE as a line. So my question is, what is the best way to achieve this?

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  • Tree-like queues

    - by Rehno Lindeque
    I'm implementing a interpreter-like project for which I need a strange little scheduling queue. Since I'd like to try and avoid wheel-reinvention I was hoping someone could give me references to a similar structure or existing work. I know I can simply instantiate multiple queues as I go along, I'm just looking for some perspective by other people who might have better ideas than me ;) I envision that it might work something like this: The structure is a tree with a single root. You get a kind of "insert_iterator" to the root and then push elements onto it (e.g. a and b in the example below). However, at any point you can also split the iterator into multiple iterators, effectively creating branches. The branches cannot merge into a single queue again, but you can start popping elements from the front of the queue (again, using a kind of "visitor_iterator") until empty branches can be discarded (at your discretion). x -> y -> z a -> b -> { g -> h -> i -> j } f -> b Any ideas? Seems like a relatively simple structure to implement myself using a pool of circular buffers but I'm following the "think first, code later" strategy :) Thanks

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  • Pass form data from block to a page view in Drupal

    - by abdesignuk
    I am using the location module and views module for a postcode search, which works fine in a page display using views. However I want the user to be able to enter their postcode into a block on the homepage and clicking submit my module sends them to the page created in views and the postcode is set as a session S_SESSION['postcode'] before sending to this page, next I want the location page to load but using the session to display the locations automatically. Any ideas I am using hook_form_submit() and inside that declaring the $form_state as a session and then using $form_state['redirect'] to sent to the views page path.

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  • ServerVariables and POST Data

    - by tyndall
    I've got a piece of tracking code which is capturing REMOTE_HOST, SERVER, REQUEST_METHOD, SCRIPT_NAME and QUERY_STRING. It grabs these from ServerVariables and sticks them in a database by user and IP. What is the best way to pick up the exact contents of what was posted back to a URL in ASP.NET? Is there an HTTP_POST? I'd rather not grab something and then have to parse it.

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  • Mysql: create index on 1.4 billion records

    - by SiLent SoNG
    I have a table with 1.4 billion records. The table structure is as follows: CREATE TABLE text_page ( text VARCHAR(255), page_id INT UNSIGNED ) ENGINE=MYISAM DEFAULT CHARSET=ascii The requirement is to create an index over the column text. The table size is about 34G. I have tried to create the index by the following statement: ALTER TABLE text_page ADD KEY ix_text (text) After 10 hours' waiting I finally give up this approach. Is there any workable solution on this problem? UPDATE: the table is unlikely to be updated or inserted or deleted. The reason why to create index on the column text is because this kind of sql query would be frequently executed: SELECT page_id FROM text_page WHERE text = ?

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  • IndexOutOfRangeException when a stream is a multiple of the buffer size

    - by dnord
    I don't have a lot of experience with streams and buffers, but I'm having to do it for a project, and I'm stuck on an exception being thrown when the stream I'm reading is a multiple of the buffer size I've chosen. Let me show you: My code starts by reading bufferSize (100, let's say) bytes from the stream: numberOfBytesRead = DataReader.GetBytes(0, index, output, 0, bufferSize); Then, I loop through a while loop: while (numberOfBytesRead == bufferSize) { BufferWriter.Write(output); BufferWriter.Flush(); index += bufferSize; numberOfBytesRead = DataReader.GetBytes(0, index, output, 0, bufferSize); } ... and, once we get to a non-bufferSize read, we know we've hit the end of the stream and can move on. But if the bufferSize is 100, and the stream is 200, we'll read positions 0-99, 100-199, and then the attempt to read 200-299 errors out. I'd like it if it returned 0, but it throws an error. What I'm doing to handle that is, well, a try-catch: catch (System.IndexOutOfRangeException) numberOfBytesRead = 0; ...which ends the loop, and successfully finishes the thing, but we all know I don't want to control code flow with error handling. Is there a better (more standard?) way to handle stream reading when the stream length is unknown? This seems like a small wrinkle in a fairly reasonable strategy for reading streams, but I just don't know if I've got it wrong or what. The specifics of this (which I've cleaned up a little bit for posting) are a MySqlDataReader hitting a LARGEBLOB column. It's working whenever the buffer is larger than the number of returned bytes, or when the number of returned bytes is not a multiple of bufferSize. Because we don't, in that case, throw an IndexOutOfRangeException.

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  • Google Data Api returning an invalid access token

    - by kingdavies
    I'm trying to pull a list of contacts from a google account. But Google returns a 401. The url used for requesting an authorization code: String codeUrl = 'https://accounts.google.com/o/oauth2/auth' + '?' + 'client_id=' + EncodingUtil.urlEncode(CLIENT_ID, 'UTF-8') + '&redirect_uri=' + EncodingUtil.urlEncode(MY_URL, 'UTF-8') + '&scope=' + EncodingUtil.urlEncode('https://www.google.com/m8/feeds/', 'UTF-8') + '&access_type=' + 'offline' + '&response_type=' + EncodingUtil.urlEncode('code', 'UTF-8') + '&approval_prompt=' + EncodingUtil.urlEncode('force', 'UTF-8'); Exchanging the returned authorization code for an access token (and refresh token): String params = 'code=' + EncodingUtil.urlEncode(authCode, 'UTF-8') + '&client_id=' + EncodingUtil.urlEncode(CLIENT_ID, 'UTF-8') + '&client_secret=' + EncodingUtil.urlEncode(CLIENT_SECRET, 'UTF-8') + '&redirect_uri=' + EncodingUtil.urlEncode(MY_URL, 'UTF-8') + '&grant_type=' + EncodingUtil.urlEncode('authorization_code', 'UTF-8'); Http con = new Http(); Httprequest req = new Httprequest(); req.setEndpoint('https://accounts.google.com/o/oauth2/token'); req.setHeader('Content-Type', 'application/x-www-form-urlencoded'); req.setBody(params); req.setMethod('POST'); Httpresponse reply = con.send(req); Which returns a JSON array with what looks like a valid access token: { "access_token" : "{access_token}", "token_type" : "Bearer", "expires_in" : 3600, "refresh_token" : "{refresh_token}" } However when I try and use the access token (either in code or curl) Google returns a 401: curl -H "Authorization: Bearer {access_token}" https://www.google.com/m8/feeds/contacts/default/full/ Incidentally the same curl command but with an access token acquired via https://code.google.com/oauthplayground/ works. Which leads me to believe there is something wrong with the exchanging authorization code for access token request as the returned access token does not work. I should add this is all within the expires_in time frame so its not that the access_token has expired

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  • client-side data storage and retrieval with html and javascript

    - by pedalpete
    I'm building what I am hoping to be a fairly simple, quick and dirty demo app. So far, I've managed to build a bunch of components using only html and javascript. I know that eventually I'll hook-up a db, but at this point I'm just trying to show off some functionality. In the page, a user can select a bunch of other users (like friends). Then they go to a separate html page and there is some sorting info based on the selected users. So my first attempt was to put the selected users object into a cookie, and retrieve the cookie on the second page. Unfortunately, if the user changed their selection, the cookie wasn't getting updated, and my searches on StackOverflow seemed to say that deleting and updating cookies is unreliable. I tried function updateCookie(updatedUserList){ jQuery.cookie('userList',null); jQuery.cookie('userList',updatedUserList); } but though it set the cookie to null, it wouldn't update it on the second value. So I decided to put the selected users object into a form. Unfortunately, it looks like I can't retrieve the contents from the form on the client-side, only on the server-side. Is there another way to do this? I've worked in PHP and Rails, but I'm trying to do this quickly and simply before building it out into something larger and am trying to avoid any server-side processing for now, which I have managed to do up to this point.

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  • Reading data from text file in C

    - by themake
    I have a text file which contains words separated by space. I want to take each word from the file and store it. So i have opened the file but am unsure how to assign the word to a char. FILE *fp; fp = fopen("file.txt", "r"); //then i want char one = the first word in the file char two = the second word in the file

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  • Consume a JSON webservice and process data in Android

    - by user1783391
    I am trying to consume a the webservice below http://62.253.195.179/disaster/webservices/login.php?message=[{"email":"[email protected]","password":"welcome"}] This returns a JSON array [{"companyuserId":"2","name":"ben stein","superiorname":"Leon","departmentId":"26","departmentname":"Development","companyId":"23","UDID":"12345","isActive":"1","devicetoken":"12345","email":"[email protected]","phone":"5456465465654","userrole":"1","chngpwdStatus":"1"}] My code is below try{ String weblink = URLEncoder.encode("http://62.253.195.179/disaster/webservices/login.php?message=[{\"email\":\"[email protected]\",\"password\":\"welcome\"}]"); HttpParams httpParameters = new BasicHttpParams(); int timeoutConnection = 7500; HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection); int timeoutSocket = 7500; HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket); HttpClient client = new DefaultHttpClient(httpParameters); HttpGet request = new HttpGet(); URI link = new URI(weblink); request.setURI(link); HttpResponse response = client.execute(request); BufferedReader rd = new BufferedReader(new InputStreamReader( response.getEntity().getContent())); result = rd.readLine(); JSONObject myData = new JSONObject(result); JSONArray jArray = myData.getJSONArray(""); JSONObject steps = jArray.getJSONObject(0); String name = steps.getString("name"); } catch (JSONException e) { e.printStackTrace(); } But its not working and I am not 100% sure this is the best way to do it. 11-10 10:49:55.489: E/AndroidRuntime(392): java.lang.IllegalStateException: Target host must not be null, or set in parameters.

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