Java C++ Makefile Perl
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Vim + TopCoder = VimCoder

VimCoder Logo

This plug-in makes it easy to use Vim as your text editor in the TopCoder Competition Arena. It aims to be minimal in comparison to other editors such as KawigiEdit or CodeProcessor plug-in chains while also providing enough functionality to also be useful.


  • Works on any platform that the TopCoder Arena applet itself supports.
  • Works with any language supported by TopCoder.
  • Keeps track of your code files locally so you always have a copy.
  • Downloads and stores a copy of the problem statement with your code for off-line viewing.
  • Has support for simple templates (default templates provided only for C++ and Java).
  • Test-case "drivers" can be generated locally with the example test-case data (currently C++ only).

Build Status

Build Status


This software is licensed according to the terms and conditions of the BSD 2-Clause License. Please see the COPYING file for more information. This project is neither supported nor endorsed by TopCoder, Inc.


The latest VimCoder jar file can be downloaded from the script page.


Unfortunately, installation is a bit cumbersome, but it is what it is:

  1. Download the latest version of the VimCoder jar file.
  2. Run the TopCoder Arena applet and log in.
  3. Click the "Options" menu and select "Editor" to show the editor preferences.
  4. Click the "Add" button to bring up a new window.
  5. For "Name," type "Vim" or whatever you want to represent this plug-in.
  6. For "EntryPoint," type "com.dogcows.VimCoder" without the quotes.
  7. For "ClassPath," click on "Browse" and locate the VimCoder jar file. The third field should now have the path to the jar file.
  8. Click "OK" to close the window with the three fields.
  9. Click "Save."

You should now be able select "Vim" (or whatever you entered into the first field) as your editor from the pull-down list on any problem statement window.


Depending on your preference or system attributes, you may want or need to first configure the plug-in so that it will work how you want it to. You can bring up the plug-in preferences window by following these steps:

  1. Run the TopCoder Arena applet and log in.
  2. Click the "Options" menu and select "Editor."
  3. In the new window, make sure the entry for VimCoder is selected from the list, and click the "Configure" button.

VimCoder Preferences

Storage Directory

VimCoder saves the problem files and the code you're working on in a particular directory you can set. By default, this directory is .vimcoder in your home directory. This is an "invisible" directory on most systems. Within this storage directory are several sub-directories, one for each problem you open. Each sub-directory is named after the problem identifier and contains your source code and other files related to the problem.

If you want to change the storage directory, click the "Browse" button in the VimCoder preferences window and navigate to the directory you would like to use. If you have already saved some problems to the previous storage directory, you may also want to actually move the directory to the new location so that VimCoder can find the work you've already done.

Beginning with VimCoder 0.3.5, there is a new option for an alternative directory structure. It is not enabled by default, but it may be in the future. Rather than having directories named after problem identifiers, the new structure uses two levels of directories. On the first level, directories are named after the contest associated with the problem (e.g. SRM-144-DIV-1), and on the second level, directories are named after the problem's point value (e.g. 300). This directory structure may be preferable if you ever want to browse your repository since the contest name and point values are more easily identifiable than the problem identifier.

If this new directory structure is enabled, it will only apply to new problems. VimCoder will not try to reorganize your current repository, though you are welcome to do it manually yourself if you would like to switch to the new directory structure.

Vim Command

By default, VimCoder tries to invoke Vim using the gvim command (or C:\WINDOWS\gvim.bat on Windows). This will typically work just fine unless you don't have gvim in your PATH (or your installation of Vim on Windows didn't include the wrappers for the command line). If you get errors about the vim process not being able to run and no Vim session comes up when you use the VimCoder plug-in, you need to either make sure the Vim command exists in your PATH, or else change the Vim command in the VimCoder preferences window to something else.

You may use an absolute path to your vim executable, such as /usr/local/bin/gvim or C:\Program Files\Vim\vim73\gvim.exe or wherever your actual Vim executable is. You may also invoke vim through some other command (e.g. xterm -e vim or gnome-terminal -e vim --).

The xterm example above demonstrates using Vim without the GUI, running in a terminal emulator. You can enter any elaborate command you want as long as Vim ultimately gets executed with the arguments that will be appended to the command when it is invoked. After changing this value and saving your preferences, the command you enter will be used the next time you open a problem.


To use VimCoder once it is installed and configured, go to a room in the TopCoder Arena applet and open one of the problems. If you have set VimCoder as your default editor, you will see the usual problem statement window come up as well as a separate Vim editor window. Otherwise, you can change the editor from the problem statement window, and the Vim editor window will come up. You will see that the area usually devoted to editor will be used for log messages; you will do your actual coding in the Vim window that comes up.

Just enter your code into the Vim window and use the regular TopCoder Arena applet buttons to compile, test, and submit your code.

Pro Tip: If you accidentally close your Vim session, you can get it back by switching to a different editor (such as the default editor) and then switching back to VimCoder. Alternatively, the session will also reappear (and load a buffer to a different source code file) if you switch languages.

Storage Directory Structure

Knowing about the files created by VimCoder is useful if you ever need to do anything advanced. When you open a problem, VimCoder will check to see if you have already opened that problem by looking for the problem and solution files. If these files are found, it will load your previous work. Otherwise, it will fill out the templates based on the problem class name, parameter types, and so on, and will create several files in a sub-directory of the main storage directory:


This is the file where you write your solution code. If the class name for the problem was BinaryCode and your language was Java, the name of this file would be When you open a problem, Vim will load this file into a new buffer so that you can start coding. If there is a template for the language you're using, that template will be used to fill in this file to give you a reasonable place to start. When you save your code to TopCoder or compile remotely, this is also the file that will be read to provide the code for your solution.


This file contains the example test cases that are associated with the problem. The format is pretty simple. For each test case, there is one line for the expected return value followed by the inputs (i.e. the method arguments), in order, each on its own line. The format of this file is meant to be easy for a human to write and easy for a program to read so that a driver program (more on this later) can easily be written to run the test cases against your code.

While you are coding a solution, you may want to open this file in a new buffer (type ":e testcases.txt") and add additional test cases to make sure your code doesn't mess up on edge cases for which an example test case was not provided.


This file contains the problem statement which is what you see in the top half of the problem window. You can load this in a browser to read the particulars of the problem when you aren't running the TopCoder Arena applet. You typically shouldn't edit this file, but it's up to you.


If there exists a Makefile template for the selected language, it will also be filled out and saved in the problem directory. The purpose of the Makefile is to compile your code locally. You can execute targets in the Makefile using Vim's :make command. You also shouldn't need to edit this file directly, but of course you can if the need does arise. Exactly what happens when you use the :make command depends on the Makefile template.

If you are using the default Makefile template for C++, typing ":make" without any arguments will compile your code. Typing ":make run" will run all of the test cases against your code. Typing ":make test" will also run the test cases against your code, except it will abort at the first failed test.

A Makefile template is not yet provided for any other language, but you can write one yourself if you are so inclined. Read on to learn how templates work.

Important: Make sure you understand the difference between compiling locally and compiling remotely (on the TopCoder servers). If you use the Makefile to compile your solution (and maybe run the tests), you are not interacting with the TopCoder servers at all. When you compile remotely, you are sending a snapshot of your current solution to the servers for processing. The distinction becomes important when it comes time for you to submit your solution. When you push the "Submit" button, you are submitting the last version that was uploaded to the TopCoder servers (by compiling remotely), and that may be different from what is currently in your Vim buffer, even if your Vim buffer was saved to disk. Therefore, it is very important that you get into the habit of always pushing the "Compile" button right before you submit your code. This point can't be overemphasized.


If there exists a driver template for the selected language, it will also be filled out and saved in the problem directory. If the language was currently set to C++, the driver code would be in the file. You normally don't have to do anything with this file. It just provides supporting code for running the test cases against your code.

The driver should output TAP (Test Anything Protocol) so that tests can be run in a test harness such as prove. The default Makefile template has a prove target (type ":make prove") that can run the tests in a test harness; the test harness is prove unless otherwise configured. TAP output is also very human-readable all by itself, so having a test harness isn't really required.

A default driver template is currently only provided for the C++ language. You could write your own template if you wanted to.


Sometimes the TopCoder Arena applet will pass back what source code it has saved. This will be saved in a file named after the class, without any file extension. You can open this file if you need to access this code for any reason (say, you messed up some code and need to revert back to the last time you saved from the TopCoder Arena applet).


VimCoder comes with default templates for C++ and Java, but you can create your own customized templates for any language supported by TopCoder. To use your own template, you need to add a file to the storage directory with a file name depending on the language. The file name should start with the name of the language and end with "Template" with no file extension. For example, if you wanted to create a C# template and your storage directory was /home/foo/.vimcoder, you would need to create the file /home/foo/.vimcoder/C#Template.

A template is like a regular source code file with special keywords that will be replaced as the template is "filled out" whenever you open a new problem. Keywords are surrounded by two dollar signs so they're not confused with other parts of the source code. The template expansion process is rather simplistic, so if you can't get the right format for the terms you need, you might have to change the plug-in source code to get the effect you're trying to achieve. Here are the possible keywords and replacement terms:


This keyword is replaced by the name of the class you must use in your solution to the problem.


This keyword is replaced by the name of the public method your class needs to have.


This keyword is replaced by the type of the return variable of your public method.


This keyword is replaced by a comma-separated list of method parameter types and names.

Other keywords are also available, but the rest are intended to be used in driver or Makefile templates, though any keyword can be used in any type of template. You can create other types of templates by adding specially-named files to the storage directory. Driver templates are named starting with the name of the language and ending with "Driver" with no file extension. Similarly, Makefile templates are named starting with the name of the language and ending with "Makefile" with no file extension.

Drivers provide additional code that allows the test cases to be run against your solution. Currently, Makefile and driver templates are only provided for the C++ language. Makefiles should have the commands needed to compile the solution source code and/or make a driver program that will perform the tests. If you want automatic building and testing for one of the other languages, you will need to create a driver and Makefile template for that language. Here are more keywords that may be useful for these types of templates:


This keyword is replaced by C-style declarations of the method parameters. In other words, each parameter is declared with its type on its own line terminated by a semicolon.


This keyword is replaced by a comma-separated list of only the method parameter names.


This keyword is replaced by a list of the method parameter names separated by the C++ output stream operator (<<). The C++ driver template uses this to display the input values of the test case data.


This keyword is replaced by a list of the method parameter names separated by the C++ input stream operator (>>). The C++ driver template uses this to read in the test case data from testcases.txt.

To give you an idea of how this all fits together, here is an example template for Java, similar to the built-in default Java template:

import static java.lang.Math.*;
import static java.math.BigInteger.*;
import static java.util.Arrays.*;
import static java.util.Collections.*;
import java.math.*;
import java.util.*;

public class $CLASSNAME$ {

Notice that it looks just like regular code but has some keywords surrounded by dollar signs that will be expanded to real values. Something like this could be saved in a filed named JavaTemplate in your VimCoder storage directory.

Potential Pitfalls

Vim Client/Server

VimCoder requires Vim's client/server feature in order to work. If the log is showing errors with the invocation of Vim or if it's just not working and has other strange symptoms, make sure your version of Vim supports the client/server feature. If you are unsure, use Vim's :version command and look for "+clientserver" in the output. If you see "-clientserver" instead, then you'll need to get yourself another version of Vim.

I think this feature was introduced in Vim 6.x, but I haven't done any testing with any versions of Vim less than 7.2. If you're still on 6.x, you should really upgrade anyway.

Vim Settings Not Applied

The problem is that sometimes your settings (in your vimrc file) are not being applied as you would expect. This may be because you are using setlocal in your vimrc file rather than set. The setlocal command applies settings only to the current buffer or window (see :help setlocal for more information), but VimCoder works by first launching Vim and then loading a brand new buffer.

The solution is to consider whether or not such settings should actually be global; if they should be global, change setlocal to set in your vimrc file. Alternatively, if you want certain settings to be set only for certain kinds of buffers, you can use the autocmd command to selectively set settings according to file path pattern and various events. See :help autocmd for more information.