dsa-tutor

A guided tutor for data-structures-and-algorithms problems, including LeetCode-style exercises. It uses questions and small hints to help you develop the solution yourself rather than giving you finished code immediately.

In plain words
What is it for?
Use it to work through an algorithm problem, choose an approach, examine mistakes and their causes, and reach a solution with gradually increasing help.
Why use it?
It keeps you working through the difficult parts, so you learn how to solve similar problems instead of memorising one answer.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/far-200/think-before-code/dsa-tutor
Any agent
npx skills add Far-200/think-before-code --skill dsa-tutor
Clone the repo
git clone --depth 1 https://github.com/Far-200/think-before-code

Made for: Claude Code, Codex.

Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,672 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00060 $0.02672
Opus 5 $0.00030 $0.01336
Sonnet 5 $0.00012 $0.00534
Haiku 4.5 $0.00006 $0.00267

Measured 2d ago against content hash dba693933d53, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dsa-tutor scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/dsa-tutor/SKILL.md · 347 lines

How it starts

The opening of the file, as written. The whole thing — 347 lines — stays where its author put it; the contents beside it link to each section on GitHub.

DSA Tutor

Why this exists

Left alone, an LLM drifts toward maximum helpfulness: stuck user → full solution, complexity analysis, dry run, code in four languages. That is the failure mode. It removes the struggle that actually builds the skill.

This skill exists to interrupt that drift on purpose.

Its scope is a DSA problem worked end to end. Reviewing existing non-DSA application code — a service, a pull request, a module from a real codebase — is code-review-coach's session, not this one's.

The circuit breaker

Before every response, run this check silently:

Is my next message about to remove productive struggle?

  YES → do not reveal the solution.
        Ask a question instead, or give the smallest possible nudge.

  NO  → continue normally.

Hard stop: if the next sentence you're about to write starts with "Here's the solution," "The answer is," or equivalent — stop. Replace it with a question that tests what the learner has actually worked out so far.

Response protocol

  • Inspect what the learner already gave you before asking anything (see First response).
  • Move through hints at the lowest level that can plausibly move the learner forward (see Hint escalation).
  • Never write code until the conditions in Code circuit breaker are met.
  • Never confirm correctness until Verification discipline is satisfied.
  • Close out through After the problem clicks, not an immediate re-teach.
  • Keep every tutoring message small (see Strict response behavior).

First response

Before asking anything, check what the learner already put in their message: an approach, code, a dry run, complexity reasoning, or a description of where they're stuck.

  • If they already gave you one or more of these, do not ask them to repeat it.
  • Identify the single most important missing piece and ask one targeted question about it.
  • If they gave you nothing but the problem statement, ask them to describe a brute-force approach first — nothing more.

Read the full file on GitHub · 347 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 347 lines · 60 tokens per session scan A dba693933d53

Subscribe to this mod's changes

dsa-tutor is a skill published in the GitHub repository Far-200/think-before-code (8 stars, last pushed 18d ago), licensed MIT. It adds 60 tokens to every session and 2,672 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories

interactive-leetcode-mcp

Use when the user wants to practice LeetCode problems, submit solutions, or set up LeetCode integration. Covers MCP server installation, learning-guided practice flow, solution submission, and authentication.

SPerekrestova/interactive-leetcode-mcp · 46 tokens

leetcode-helper

Expert LeetCode problem solver for optimized C++ coding interview solutions. Use when: the user pastes a LeetCode problem, asks for an optimized algorithm, wants C++ LeetCode code, needs a dry run, asks for line-by-line explanation, wants a hint before the solution, wants brute force to optimized progression, wants…

Zephyrex21/claude-leetcode-helper · 98 tokens

configure-profile

Create or update the global learner profile. Interviews the learner using the measurement checklist in references/PROFILE-TEMPLATE.md and writes the structured result to profile/PROFILE.md. Use when a new learner sets up Upstack for the first time, or after completing a course to update skills and Dreyfus levels.

ishands/upstack · 64 tokens

create-course

Scaffold a new course directory from the COURSE.md schema. Creates the directory structure, populates COURSE.md with YAML frontmatter and markdown template sections, and creates stub assignment directories. Use for curated courses (core/courses/) or personal courses (custom/courses/) in any domain.

ishands/upstack · 60 tokens

start-course

Initialise a learning session. Checks for an existing journal in progress/ /journal.md, creates one from the template if missing, loads the course definition, and calibrates to the learner's declared context. Use when starting a new course or resuming after a break.

ishands/upstack · 60 tokens

start-learning-path

Enrol in a curated learning path. Discovers available paths, presents project options in plain language, records the learner's choice, initialises the integration journal, and displays the full course roadmap. Run once at the start of the path — not at the start of each course. Distinguishes enrolment (path level…

ishands/upstack · 83 tokens