Clarify Friendship Rules and Money-Transfer Semantics Before Choosing an Algorithm

Discuss how you would clarify and implement a coding task involving friendship relationships and money transfers. The relationship between friendship and transfer behavior is unspecified, so start by defining the missing requirements instead of assuming a particular graph problem or financial policy.

Part 1 — Establish the Operation Contract

Identify the inputs, operations, outputs, and error cases needed to turn the task into an executable specification. In particular, clarify whether friendship controls eligibility, identifies a route, or merely stores separate relationship data.

What This Part Should Cover

Distinguish several plausible interpretations and explain which missing answers change the algorithm. Do not claim that any one interpretation is required.

Part 2 — Develop One Explicitly Hypothetical Design

Choose one interpretation, label its rules as assumptions, and describe the state, algorithm, and invariants. Explain how the design would change if the friendship rule were different.

What This Part Should Cover

Connect relationship representation to the declared rule. If balances are modeled, explain value conservation and rejection without partial updates. If the task only asks for reachability, do not invent account settlement behavior.

Constraints

No friendship direction, balance model, allowed-transfer rule, optimization objective, concurrency model, or error policy is supplied. This is a specification-and-design exercise; it has no single expected numeric output or fixed executable API.

Clarifying Questions

• Are friendship edges directed, and may relationships change?
• Does a transfer require direct friendship, any connecting path, or no relationship check?
• Are we finding a path, recording a transfer, or updating account balances?
• Are insufficient funds, duplicate requests, or concurrent operations in scope?