CPTerm

CPTerm is a Firefox and Chrome extension that brings competitive programming problems from LeetCode and HackerRank to your favorite code editor.

Features

• Sync your solutions from any editor to the browser, ditching clunky browser-based editors
• Export problem statements to PDF or HTML, or another format using Pandoc or LibreOffice
• Load past solutions from your filesystem
• Submit your code and run test cases from external scripts
• Run scripts when opening problems

Installation

Requirements

• Firefox >=128, or Chrome/Chromium >=131
• Java 8 or newer

Install native messaging host

The CPTerm host is a Java program distributed as a jar file. It's responsible for interacting with the filesystem, rendering problem statements, running hook scripts, and handling commands over TCP.

Troubleshooting

Ensure that the java binary of the JRE is in your PATH. This should happen by default if you used an installer or your Linux distribution's package manager, but run java -version in a terminal or command prompt to make sure. Additionally, the system-wide JRE will be used to run the host itself.

CLI installer

Run the command:

java -jar cpterm-XXX.jar --install -b BROWSER [-b BROWSER...] [-d DIRECTORY]

where BROWSER is one of firefox, chrome, or chromium and DIRECTORY is the install directory, set to a reasonable default for your OS if not specified. Multiple browsers can be specified.

GUI installer

Run the jar by either double-clicking it or running java -jar cpterm-XXX.jar where XXX is the version. Select the browser(s) you plan to use with CPTerm and leave the location as the default unless you know what you are doing.

Install extension

• Firefox: Mozilla Add-ons
• Chrome/Chromium: not available on Chrome Web Store due to $5 fee

Build requirements

• Maven 3.8.7 or newer
• Node 18.19.0 or newer
• npm 9.2.0 or newer

Build extension

You must have node and npm installed. In the extension directory, run the commands:

npm install
npm run build
npm run zip:firefox
npm run zip:chrome

This will produce cpterm-firefox.zip and cpterm-chrome.zip files in the extension/dist directory, which can be used to install the extension.

Build host

You must have Maven installed. In the host directory, run:

mvn clean package

Basic usage

Each time you load a page of a supported website, the Open problem button will appear in the upper-left corner. Alt-Shift-C is a shortcut for this button. If the page is a problem page, clicking the button will, in this order:

• wait for the problem to be scrapeable (the description must be visible);
• run the pre-problem script (if enabled);
• render the problem statement to a file (if enabled);
• create a new, or read an existing, problem code file;
• listen on the filesystem for changes to the problem code file; and
• run the post-problem script (if enabled)

A problem being open means the file listener is running for, and submissions will be made to, that problem. Only one problem can be opened at a time. The typical flow is: navigate to a problem page, click Open problem, write your solution, test/submit using cpt, and finally close the browser tab to free resources (delete temporary files and end the host process).

Configuration

CPTerm is configured using an options page in your browser's extension manager.

Files

The two main files for a problem are the code file and problem statement file. These can be organized in a problem directory, but temporary files are used by default. When a problem directory path is set by the user, a sub-directory is created inside it for each problem. Each sub-directory is named according to the problem's name.

Code file

This file contains your solution. It is created by CPTerm when you open a problem for the first time, and is initially populated with the template code provided by the website. If you are using a problem directory and the problem has been opened before (i.e., there exists a sub-directory with the problem name), the old code file will be read into the web-based editor. Changes to this file are monitored by CPTerm and synced to the web-based editor.

Problem statement file

This file contains the problem description and short examples provided by the website. It ideally does not contain editorials, discussions, test cases, or anything else on the problem page. Since it's scraped from the page HTML, behavior may change slightly with updates to the websites.

Because the problem statement is in HTML, and typically a more readable format is desired, this file can be rendered using one of three tools. By default, the Java library Open HTML to PDF is used to render to PDF, and this is the best option for most users since it works out of the box. If a different file type is desired, support also exists for Pandoc and LibreOffice, which will need to be installed separately if you want to use them. When using either of these tools, CPTerm will render SVG graphics in the problem statement to PNG since they both don't support SVG well enough. If HTML is actually the desired output, CPTerm can produce a cleaned HTML file, optionally with SVG rendered to PNG.

Test case files

These are generated when running a test case from CPTerm. Typically, three files are created: input, output, and expected output. An error file may be created if there was a compile time or runtime error, and this may or may not be accompanied by an input file. Files created by a test case are always temporary.

Scripting

Hook scripts

CPTerm can invoke pre- and post-problem scripts, which are run when the Open problem button is clicked, and after the problem files have been created and opened, respectively. The post-problem script is passed two command line arguments: the absolute paths to the code file and the problem statement file (if it exists).

Controlling CPTerm

A TCP server can be run so that CPTerm can be controlled externally; the server only accepts loopback connections. The TCP server can be used to run and submit your solution. This verbiage aligns with that of at least LeetCode and HackerRank; each of these actions corresponds to some equivalent functionality on the challenge website.

Using cpt

The included shell script cpt implements a simple client for CPTerm and should suffice for most users. It requires any implementation of nc. The script is invoked with cpt run or cpt submit, and it will format the test case output nicely, if there is any. The port number will need to be adjusted in the script if you change it in CPTerm's settings.

Using your own client

To run or submit your solution, connect to the TCP server and send one of those words followed by a line break. On Linux/Unix, you can use nc to do this, e.g.:

echo submit | nc 127.0.0.1 50000

The server's response will be one of the following:

• Lines of tab-separated values
  • Each value is a path to a text file.
  • Each line may have a different number of values.
  • 3 values: input, output, expected
  • 2 values: error, input
  • 1 value: error
• timed out
  • The action was attempted, but the scraper didn't send a meaningful response within 1 minute.
• Blank
  • Something went wrong, or no test cases were provided. For example, LeetCode doesn't show any test cases when submitting a problem which passed all hidden test cases.