rust / LEVEL 2

The view that must not outlive its source

EST.30 MIN

THEORY / RETRIEVAL

What to restore

Express the relationship between input and output lifetimes
Return a view into a collection without allocating

Lifetimes describe relationships

A lifetime parameter does not extend how long a value lives. It tells the compiler which input borrow constrains an output borrow. Returning `&'static str` is only valid when the data itself is static; it is not a shortcut for difficult annotations.

Tie handling is part of the contract

Iterator adapters can hide subtle behavior such as which equal maximum wins. Interview code should make allocation, tie-breaking and empty-input behavior explicit instead of relying on an accidental implementation detail.

CHECKPOINT

Which signature can return either input while guaranteeing that the result never outlives the selected borrow?

Confidence: 3/5

02 / IMPLEMENTATION

Implement the contract

Implement `longest_nonempty` without allocation. Return the first value when byte lengths tie, ignore empty strings, and keep the public signature unchanged.

Initializing editor…

CLOUD SANDBOXnetwork off · 256 MB · 12 s

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OUTPUT

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