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.
npx skills add Tyler-R-Kendrick/agent-skills --skill data-structuresgit clone --depth 1 https://github.com/Tyler-R-Kendrick/agent-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/tyler-r-kendrick/agent-skills/data-structures)<a href="https://agentmods.dev/skills/tyler-r-kendrick/agent-skills/data-structures"><img src="https://agentmods.dev/badge/skills/tyler-r-kendrick/agent-skills/data-structures.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00120 | $0.02467 |
| Opus 5 | $0.00060 | $0.01234 |
| Sonnet 5 | $0.00024 | $0.00493 |
| Haiku 4.5 | $0.00012 | $0.00247 |
Grade A, and why
data-structures 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 8d 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.
How it starts
The opening of the file, as written. The whole thing — 266 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Data Structures
Overview
Data structures are the foundation of efficient software. The choice of data structure determines the complexity of every operation your program performs. Knuth's The Art of Computer Programming, Volume 1: Fundamental Algorithms provides the definitive treatment of information structures -- from linear lists through trees and multilinked structures. This skill covers the major data structures, their operation complexities, and guidance on when to use each.
Arrays
A contiguous block of memory storing elements of the same type, accessed by index.
| Operation | Time |
|---|---|
| Access by index | O(1) |
| Search (unsorted) | O(n) |
| Search (sorted) | O(log n) |
| Insert at end | O(1) amortized (dynamic array) |
| Insert at position | O(n) |
| Delete at position | O(n) |
Use when: Random access is frequent, data size is known or grows by appending, cache locality matters.
Linked Lists
Elements (nodes) are stored non-contiguously; each node contains data and a pointer to the next (and optionally previous) node.
Variants
- Singly linked: Each node points to the next. Traversal is forward only.
- Doubly linked: Each node points to both next and previous. Traversal in both directions.
- Circular: The last node points back to the first, forming a cycle.
| Operation | Singly | Doubly |
|---|---|---|
| Access by index | O(n) | O(n) |
| Search | O(n) | O(n) |
| Insert at head | O(1) | O(1) |
| Insert at tail (with tail pointer) | O(1) | O(1) |
| Insert at position (given pointer) | O(1) | O(1) |
| Delete at head | O(1) | O(1) |
| Delete at position (given pointer) | O(n) for singly, O(1) for doubly | O(1) |
Use when: Frequent insertions/deletions at arbitrary positions, no need for random access, implementing stacks/queues.
Stacks
Last-In, First-Out (LIFO) structure.
| Operation | Time |
|---|---|
| Push | O(1) |
| Pop | O(1) |
| Peek/Top | O(1) |
| Search | O(n) |
What ships with it
11 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- AGENTS.md 8.7 KB
- metadata.json 814 B
- README.md 726 B
- rules/_sections.md 1.3 KB
- rules/_template.md 374 B
- rules/data-structures-choose-the-data-structure-based-on-the-dominant-operation.md 470 B
- rules/data-structures-consider-cache-locality.md 451 B
- rules/data-structures-for-concurrent-access-consider-concurrent-variants.md 447 B
- rules/data-structures-prefer-standard-library-implementations-they-are.md 456 B
- rules/data-structures-reference-knuth-s-taocp-vol.md 451 B
- rules/data-structures-remember-that-theoretical-complexity-is-not-the-full-story.md 514 B
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.
- 8d ago First seen · 266 lines · 120 tokens per session scan A 10fbd2ec0d4c
data-structures is a skill published in the GitHub repository Tyler-R-Kendrick/agent-skills (11 stars, last pushed 3mo ago), licensed MIT. It adds 120 tokens to every session and 2,467 once invoked, about $0.0006 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.
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