shortest-paths

shortest-paths is a skill for Claude Code, Codex from Arcadi4/nerdy. It costs 70 tokens per session (5,691 once invoked), scanned A, original, MIT.

An algorithm guide for finding least-cost paths through graphs, including graphs with negative edge weights or many pairs of points.

In plain words
What is it for?
Use it for Dijkstra, Bellman–Ford, DAG paths, Floyd–Warshall, Johnson’s algorithm, difference constraints, arbitrage, or related graph reductions.
Why use it?
It helps select an algorithm whose assumptions match the graph and identify issues such as negative cycles, overflow, and path reconstruction.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it for Dijkstra, Bellman–Ford, DAG paths, Floyd–Warshall, Johnson’s algorithm, difference constraints, arbitrage, or related graph reductions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/arcadi4/nerdy/shortest-paths
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.

Any agent
npx skills add Arcadi4/nerdy --skill shortest-paths
Clone the repo
git clone --depth 1 https://github.com/Arcadi4/nerdy

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for shortest-paths

README.md
[![agentmods](https://agentmods.dev/badge/skills/arcadi4/nerdy/shortest-paths.svg)](https://agentmods.dev/skills/arcadi4/nerdy/shortest-paths)
Your own site
<a href="https://agentmods.dev/skills/arcadi4/nerdy/shortest-paths"><img src="https://agentmods.dev/badge/skills/arcadi4/nerdy/shortest-paths.svg" alt="Measured on agentmods" height="20"></a>
Per session 70 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,691 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00070 $0.05691
Opus 5 $0.00035 $0.02846
Sonnet 5 $0.00014 $0.01138
Haiku 4.5 $0.00007 $0.00569

Measured 7d ago against content hash a2dc98435e19, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

shortest-paths 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 7d 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.

clrs/shortest-paths/SKILL.md · 516 lines

How it starts

The opening of the file, as written. The whole thing — 516 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Shortest Paths

Overview

Shortest-path answers are decision problems before they are algorithm names. First identify the path model, weight assumptions, graph representation, negative-cycle semantics, and whether the caller needs distances, predecessor trees, actual paths, or cycle witnesses.

Core principle: choose the algorithm whose preconditions match the weights and graph shape, prove correctness with relaxation, dynamic-programming decomposition, or reweighting, then state the production contract for representation, sentinels, overflow, and reconstruction.

Shared CLRS Conventions

  • Follow the parent clrs skill for mathematical formatting: every expression, inequality, recurrence, path weight, and asymptotic bound goes in a display LaTeX block, never in prose, headings, tables, or inline code spans.
  • Use elementary-graph-algorithms for graph representation basics, breadth-first search on unweighted graphs, depth-first search, topological sorting, and transitive-reachability prerequisites.
  • State whether the graph is directed or undirected before choosing a shortest-path algorithm. A negative undirected edge creates an immediate negative cycle under the directed-edge model unless the problem defines a different semantics.
  • State the representation before giving a running time. Adjacency lists fit single-source and Johnson-style sparse algorithms; adjacency matrices fit dense all-pairs dynamic programs.
  • Do not announce that you are reading this skill or applying a checklist. Deliver the polished answer directly.

When to Use

Use this skill for:

  • Weighted single-source shortest paths, single-destination reductions, single-pair questions, and all-pairs shortest paths.
  • Choosing among breadth-first search, DAG shortest paths, Bellman-Ford, Dijkstra, Floyd-Warshall, Johnson, repeated single-source runs, or min-plus matrix products.
  • Negative-edge and negative-cycle questions, including which vertices have finite distance, infinite distance, or unbounded-below distance.
  • Relaxation invariants, predecessor subgraphs, shortest-path trees, path reconstruction, and output verification.
  • Difference constraints, arbitrage detection, reliability paths, critical paths in acyclic project networks, bitonic-path exercises, and other graph-path reductions.
  • Production reviews where the textbook algorithm must be translated into an API contract, library choice, graph representation, memory budget, or cycle-reporting behavior.

Read the full file on GitHub · 516 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. 7d ago First seen · 516 lines · 70 tokens per session scan A a2dc98435e19

Subscribe to this mod's changes

shortest-paths is a skill published in the GitHub repository Arcadi4/nerdy (7 stars, last pushed 4mo ago), licensed MIT. It adds 70 tokens to every session and 5,691 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.

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