topher j - Developer IT

Need help on a problemset in a programming contest

- by topher

I've attended a local programming contest on my country. The name of the contest is "ACM-ICPC Indonesia National Contest 2013". The contest has ended on 2013-10-13 15:00:00 (GMT +7) and I am still curious about one of the problems. You can find the original version of the problem here. Brief Problem Explanation: There are a set of "jobs" (tasks) that should be performed on several "servers" (computers). Each job should be executed strictly from start time Si to end time Ei Each server can only perform one task at a time. (The complicated thing goes here) It takes some time for a server to switch from one job to another. If a server finishes job Jx, then to start job Jy it will need an intermission time Tx,y after job Jx completes. This is the time required by the server to clean up job Jx and load job Jy. In other word, job Jy can be run after job Jx if and only if Ex + Tx,y = Sy. The problem is to compute the minimum number of servers needed to do all jobs. Example: For example, let there be 3 jobs S(1) = 3 and E(1) = 6 S(2) = 10 and E(2) = 15 S(3) = 16 and E(3) = 20 T(1,2) = 2, T(1,3) = 5 T(2,1) = 0, T(2,3) = 3 T(3,1) = 0, T(3,2) = 0 In this example, we need 2 servers: Server 1: J(1), J(2) Server 2: J(3) Sample Input: Short explanation: The first 3 is the number of test cases, following by number of jobs (the second 3 means that there are 3 jobs for case 1), then followed by Ei and Si, then the T matrix (sized equal with number of jobs). 3 3 3 6 10 15 16 20 0 2 5 0 0 3 0 0 0 4 8 10 4 7 12 15 1 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 8 10 4 7 12 15 1 4 0 50 50 50 50 0 50 50 50 50 0 50 50 50 50 0 Sample Output: Case #1: 2 Case #2: 1 Case #3: 4 Personal Comments: The time required can be represented as a graph matrix, so I'm supposing this as a directed acyclic graph problem. Methods I tried so far is brute force and greedy, but got Wrong Answer. (Unfortunately I don't have my code anymore) Could probably solved by dynamic programming too, but I'm not sure. I really have no clear idea on how to solve this problem. So a simple hint or insight will be very helpful to me.

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Debian Apache2 and SSL

- by Topher Fangio

Hello all, I recently took over a server that is using Apache2 with SSL. I have setup a new server to which I am migrating all of the old websites so that we can more easily scale (it's a cloud server) and so that I can set everything up correctly (or at least with some sort of convention). I have read quite a few articles on setting up Apache2 and SSL with virtual hosts, but I'm a bit confused because all of the examples show three files and I only seem to have two. To compound the problem, they are all named differently (do the file extensions actually make a difference?). The examples show something to this effect: <VirtualHost X.X.X.X:443> ServerAlias something.mydomain.com ServerAdmin [email protected] DocumentRoot /var/www/project/client/site SSLEngine on SSLCertificateFile /etc/ssl/certs/mydomain-cert.pem SSLCertificateKeyFile /etc/ssl/private/mydomain-key.pem SSLCertificateChainFile /etc/ssl/certs/mydomain-ca.crt </VirtualHost> However, the files I have are: _.mydomain.com.crt gd_bundle.crt It is a wildcard certificate that we purchased through GoDaddy I believe. I believe that the first file is the actual certificate file and the gd_bundle.crt is the chain file, but that leaves me without a key file. There is also a random mydomain.csr file lying around on the old server, but it wasn't one of the files bundled with the download from GoDaddy, so I'm not really sure as to what it is. Any help in figuring out what I need to do would be greatly appreciated. I am software developer, so I know my way around computers, but I have only dabbled in server setup/maintenance. Much Thanks!

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What is the proper way to align UITableViewCells when only some have an imageView?

- by Topher Fangio

Hello all, I am new to iPhone programming and working on my first real application (i.e. one not written in a book or online) and I've run into a small problem which I could solve a multitude of ways, but feel like there should be a good solution that perhaps I am just missing. Here is the scenario: I have a UITableView with a bunch of standard UITableViewCells in it. What I want to do is toggle a green check mark when the cell is selected and I have that part working (note: I'm already using the accessoryType for something else, so I can't use it for the checkmark...besides, it's not as pretty). Unfortunately, when I toggle the checkmark like so: if (...) { cell.imageView.image = [UIImage imageNamed:@"checkmark.png"]; } else { cell.imageView.image = nil; } It makes the cell's label bounce back and forth depending on whether it is checked or not. What is the proper way to align the cell's text (set via cell.textLabel.text) regardless of whether or not it has an image set? The solutions I have come up with are: Create a blank 40x40 png image in Photoshop and set the unchecked to that Create a blank 40x40 image solely in code Set some setting that I don't know about that will align it for me Create a subclass of UITableCellView that does what I need (which would be stupid, I'd just go with option 1...) Suggestions? Thoughts? Comments? Thank you very much :-) P.S. I'd like the solution to work with OS 3.0 and 4.0 if that makes any sort of difference.

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Using respond_to ... format.json and jQuery Form Plugin by malsup

- by Topher Fangio

Hello all, I'm having a tad bit of trouble getting the jQuery Form Plugin to work properly with a file-upload field. When I use the plugin to submit the form without a file-upload field, the format.json portion of the respond_to do |format| block is called properly. However, by adding the file-upload field, it only executes the format.html portion which makes my javascript code think that an error has occurred. Has anyone run into this before or know a way to force the plugin to always use json? Alternatively, can I modify the url that the plugin uses to force Rails to render the json? Thanks very much for any help! Code below: # app/controllers/details_controller.rb def create @detail = Detail.new(params[:detail]) style = params[:detail_style].to_sym || :thumb data = { :id => '5', :url => 'test.rails' } respond_to do |format| if @detail.save flash[:notice] = 'Your image has been saved.' data = { :id => @detail.id, :url => @detail.data.url(style) } format.html { redirect_to :action => 'index' } format.json { render :json => "<textarea>#{data.to_json}</textarea>", :status => :created } else format.html { render :action => 'new' } format.json { render :json => @detail.errors, :status => :unprocessable_entity } end end end /* app/views/sidebar/_details.html.erb (excerpt) */ <% form_for(Detail.new, :html => { :multipart => true } ) do |f| %> <%= hidden_field_tag 'detail_style', 'thumb' %> <%= f.label :image, "Recent Images" %> <%= f.file_field :image%> <p> <%= f.submit "Upload" %> </p> <% end %> <script> $(document).ready(function() { var options = { dataType: 'json', success: function(json, statusText) { console.log("success: " + json); }, error: function(xhr, statusText, errorThrown) { console.log("error: " + xhr.responseText); } }; $('#new_detail').ajaxForm(options); });

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Redirect to default action in Struts 2

- by topher-j

I have an action with an empty string for name defined in the root namespace, and I want to redirect to that action from another action if a certain result is found, but it doesn't seem to work. Here's the default action <action name="" class="com.example.actions.HomeAction"> <result name="success" type="freemarker">freemarker/home.ftl</result> </action> And I'm defining the redirect in the global-results for the package: <global-results> <result name="sendToRouting" type="redirectAction"> <param name="actionName"></param> <param name="namespace">/</param> </result> </global-results> I've tried taking out the actionName parameter, but that doesn't work. If I put a name in for the HomeAction and reference it by name in the global-results it works, so I'm assuming the problem is lack of action name for the redirect. Any thoughts?

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How can I use images provided by the iPhone OS?

- by Topher Fangio

Hello all, First, let me state what brought this question about: I saw the green checkmark icon in this post and I would like to use it in my own application. However, since it looks so much like the UITableViewCellAccessoryDetailDisclosureButton my assumption is that this green checkmark icon is provided by the iPhone OS in some form or fashion. So, my question is: how can I use the green checkmark icon and/or other OS-provided images in my own applications? As a side question: where can I find a list of the OS-provided images (if they even exist)? Thanks very much for any input :-)

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Rails Cache Sweeper and Model Callback Firing

- by Topher Fangio

Hey guys, I have the following classes: class Vigil < ActiveRecord::Base after_update :do_something_cool private def do_something_cool # Sweet code here end end class NewsFeedObserver < ActionController::Caching::Sweeper observe Vigil def after_update # Create a news feed entry end end Everything works as expected. The after_update in the sweeper requires that the do_something_cool method in the model has finished before it can run properly. The problem is that the after_update in the sweeper is being called before (or perhaps at the same time as) the do_something_cool callback and it's causing problems. Does anyone know how to force the after_update in the sweeper to fire after the model callback? Is there better way to achieve this?

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Proper way to resignFirstResponder when a UITableView is touched?

- by Topher Fangio

Hello all, I have a pretty simple UITableView who's cells contain UITextFields and I need to be able to call resignFirstResponder to hide the keyboard whenever a user touches the UITableView outside of one of the cells. I have read this question/answer but it seems like a very rudimentary way to achieve this. I have read about a way to do it by converting the UITableView to a UIControl so that you can connect the TouchDown event. Does anybody know the standard or preferred way to achieve this functionality?

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