Computer Science: Add Graph Project Curriculum Files #30700

scriabin-enjoyer · 2026-01-21T00:35:32Z

Because

As decided in #28487, we will be adding a new graph project. @damon314159 started the work on this project in #29037, but, unfortunately, is not currently able to complete it at this time and handed off the rest of the project to me with the approval of @JoshDevHub.

This PR

Adds image files for a graph visualization to both ruby and js paths, with approval of the visualization from maintainers
Adds the curriculum files for the new graph project for both ruby and js paths, with approval of the lesson content from maintainers

(I will request a review for files this PR adds currently, which is just the image and the JS version of the project, then add the ruby version once the JS version is approved).

Issue

Related to #28487
Related to #29037
Related to #29783

Additional Information

For the complete addition of this project into the curriculum and website, we still need to:

Create the CDN links for the image once these files are merged and then update the link refs in these curriculum files
Add the project's seed data to the main site repo
Update both the ruby and js Knight's Travails curriculum files to reflect the addition of this project

Once this PR is merged, I will submit another PR to add the CDN links. However, all 3 issues referenced in the Issue section require these 3 points listed here to be completed in order to be closed. I am entirely willing to take on these tasks as well unless maintainers want to wait on fully adding this project to the site for whatever reason.

(Aside: In the original "Add new graph project" PR that was started by damon314159, josh asked if I would like to "Take ownership of the PR", and I didn't know what that meant because I don't have push priveleges for damon's fork, so I just opened this PR instead which also allowed me to rebase damon's work onto main)

Pull Request Requirements

I have thoroughly read and understand The Odin Project curriculum contributing guide
The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
The Because section summarizes the reason for this PR
The This PR section has a bullet point list describing the changes in this PR
If this PR addresses an open issue, it is linked in the Issue section
If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
If any lesson files are included in this PR, they follow the Layout Style Guide

- Includes Khan academy article from the Knights Travails project - Adds a description of simple vs nonsimple graphs as this is somewhat necessary for the semantics of the addVertex, addEdge, and query functions - Removes various explanations about graphs because the Khan academy article allows us to offload in-house explanations

- Replaces old G4G link with new w3schools link because it is much better and has a nice interactive graph visualization module - Adds optional article comparing adjacency lists and matrices - Adds requirement for learners to implement toString() method because adjacency list is easy to visualize; don't need to provide a complex function to print something like a BST - Updates some of the language in the interface descriptions to be more explicit about the semantics of each method - Updates 'Test Your Graph' section to reflect the use of adj-list instead of matrix

scriabin-enjoyer · 2026-01-21T01:35:03Z

@ maintainers, please review the graph image and the JS version of the project and let me know if it is sufficient, then I will commit the ruby version as well and mark this draft as "Ready for review". Some notes:

My idea for the graph visualization image was to give a relevant example for the odin project, i.e. a web-related example. The idea was to depict a network that gets traversed during a web request, i.e. DNS -> HTTP (although it doesn't depict exactly how a resolver queries DNS, but the idea is the same). I understand that DNS isn't really covered by the curriculum, but I thought it serves as a bit of foreshadowing for learning more about web-related network activities in the future, and it's not too difficult to understand what a "name server" is if you google. But if anyone takes issue with this then I am agreeable to changing it (but I would like to keep it in lol).
The in the old PR, we discussed adding a traversal method to the API, like pathExists(x, y), that traverses the graph. However, this actually requires a DFS or BFS to be performed on the graph in order to determine if such a path exists (have to determine if the nodes belong to the same connected component, which necessarily requires a DFS). It seemed to me that Josh wants to keep the CS sections of the Ruby/JS courses to be not so bloated. Thus I elected to leave it out and not have any search methods at all.

The specs for each of the methods on the class are updated to be much more explicit about the semantics of each function and what these functions should return if they should return anything meaningful. My idea for the mutator methods (add/remove methods) are for them to be idempotent and effectively silent. Other methods are more or less self-explanatory. This commit also removes a little hint about what data structures to use to represent the adjacency list because the w3schools article is actually quite sufficient for this, even though it doesn't give a concrete implementation.

scriabin-enjoyer · 2026-01-23T19:44:05Z

Okay so after thinking about this PR for a bit more, I decided to just finish all the work for now and mark for review so I can get better, more complete feedback on the entire project as it is.

Updated image to not reference anything fancy like DNS so that its understandable (although it looks kinda weird still... the way I made it lol)
Saw the recent (last dec.) Linked List PR that updated the language in the project spec to get ready for the testing revamp, so I thought I might as well do something similar and updated the language for the spec in this project. I tried lol. Surely it could be better.
added ruby version, basically the same as js version.

LMK how it is, open to any and all suggestions for improvements — at your convenience.

mao-sz

I'll leave the content reviewing to a more DSA-oriented maintainer. Just a few quick formatting points from me:

As per our style guide, headings should be in sentence case, not title case
Some of your indentations are more than necessary e.g. children of ordered list items need indenting 3 spaces from the parent but on line 81 of both (and maybe other places), it's indented 4 spaces.
List items don't actually need blank lines between them by default (only in cases where you have like a code block as part of it and the code block does need a blank line either side). The extra blank line in normal cases just makes an extra p tag render in the HTML which isn't necessary. Most your lists don't have blank lines between items but your assignment list does, so we could do with some consistency there.

…yle guide

scriabin-enjoyer · 2026-01-26T21:38:57Z

@mao-sz thanks very much for your input! admittedly I didn't review the layout guide before making all the changes. I've have rectified this and hopefully its good now.

JoshDevHub

This looks pretty good. I have one small nitpick right now. I'll have to think on some things about where we are with testing before approving, but I'm hopeful I can accept and merge this soon.

JoshDevHub · 2026-01-31T21:48:53Z

javascript/computer_science/project_graph.md

+1. `getNeighbors(value)`: Returns an array of all the vertices that are adjacent to the vertex `value`, or `undefined` if `value` is not in the graph.
+1. `getCommonNeighbors(value1, value2)`: Returns an array of all the vertices that are adjacent to both of the vertices `value1` and `value2`, or `undefined` if either `value1` or `value2` are not in the graph.


Suggested change

1. `getNeighbors(value)`: Returns an array of all the vertices that are adjacent to the vertex `value`, or `undefined` if `value` is not in the graph.

1. `getCommonNeighbors(value1, value2)`: Returns an array of all the vertices that are adjacent to both of the vertices `value1` and `value2`, or `undefined` if either `value1` or `value2` are not in the graph.

1. `getNeighbors(value)`: Returns an array of all the vertices that are adjacent to the vertex `value`. If the given `value` isn't in the graph, return `undefined`..

1. `getCommonNeighbors(value1, value2)`: Returns an array of all the vertices that are adjacent to both of the vertices `value1` and `value2`. If either of the given values aren't in the graph, return `undefined`.

Just splitting the undefined return variant into new sentences because I find that reads a bit better.

Also I'm lazy and not going to make a suggestion specific to the Ruby lesson, but I'd like the same structure to for the Ruby lesson as well.

Yeah I think it reads better like that as well (and sort of standardizes the phrasing for all the DSA projects). Several of the method descriptions here beyond these getNeighbor functions are phrased like:
"Returns X if condition or Y otherwise"

I'll make similar changes to your suggestions where I think it's appropriate.

damon314159 and others added 5 commits January 19, 2026 19:43

feat(CS): Add new graphs project

90bfc3b

Expand on reasoning behind representation choice

31cc835

Graph Project: Add images

444c46f

github-actions bot added Content: JavaScript Involves the JavaScript course Content: Ruby Involves the Ruby course labels Jan 21, 2026

scriabin-enjoyer changed the title ~~Computer Science: Add New Graph Project Curriculum Files (Draft)~~ Computer Science: Add Graph Project Curriculum Files (Draft) Jan 21, 2026

Graph Project: Remove Additional Resources

0c8d22b

JoshDevHub mentioned this pull request Jan 21, 2026

Computer science: Add new graphs project #29037

Closed

7 tasks

JoshDevHub self-requested a review January 21, 2026 18:08

scriabin-enjoyer added 4 commits January 23, 2026 08:48

Graph Project: Remove old images

0c23271

Graph Project: Add better images

052c0fe

Graph Project: Add ruby version

7f4d252

scriabin-enjoyer marked this pull request as ready for review January 23, 2026 19:38

scriabin-enjoyer changed the title ~~Computer Science: Add Graph Project Curriculum Files (Draft)~~ Computer Science: Add Graph Project Curriculum Files Jan 23, 2026

Graph Project: Fix syntax errors

da64d38

mao-sz reviewed Jan 26, 2026

View reviewed changes

Graph Project: Update formatting for better compliance with layout st…

6d5ad29

…yle guide

JoshDevHub mentioned this pull request Jan 30, 2026

Audit the project requirements in the computer science section to make sure they're fit for having learners write tests while working through them. #30513

Open

JoshDevHub requested changes Feb 4, 2026

View reviewed changes

Graph Project: Update language for better phrasing

f633d54

scriabin-enjoyer requested a review from JoshDevHub February 5, 2026 21:30

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Computer Science: Add Graph Project Curriculum Files #30700

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		1. `getNeighbors(value)`: Returns an array of all the vertices that are adjacent to the vertex `value`, or `undefined` if `value` is not in the graph.
		1. `getCommonNeighbors(value1, value2)`: Returns an array of all the vertices that are adjacent to both of the vertices `value1` and `value2`, or `undefined` if either `value1` or `value2` are not in the graph.

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scriabin-enjoyer commented Jan 21, 2026

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