The Reliquary Beneath the Drowned Chapel

Commission of the Warden's Guild of Bitwick

Beneath the Drowned Chapel the Warden's Guild keeps a reliquary with a fixed number of niches. Adventurers bring back relics from the wild, and when every niche is full the weakest relic is carried back out. The guild needs a ledger that decides, without fail, which relic leaves.

Implement a class Reliquary:

• constructor `(capacity)`: capacity is a non-negative integer, the maximum number of relics stored at once. The reliquary starts empty.
• `stow(name, power)`: name is a non-empty string, power a non-negative integer. Returns a string.
• `invoke(name)`: returns an integer.
• `peek(name)`: returns an integer.
• `seal(name)`: returns a boolean.

Every stored relic has a power, an invocation count, a last-touched time, and a sealed flag. To *touch* a relic is to set its last-touched time later than every earlier touch.

`stow(name, power)` 1. If a relic named name is already stored, its power becomes power and it is touched. Its invocation count and sealed flag are unchanged. Nothing is removed. Return "". 2. Otherwise, if fewer than capacity relics are stored, store it with invocation count 0, unsealed, and touched. Return "". 3. Otherwise the reliquary is full. The contenders are every *unsealed* stored relic plus the newcomer, which counts as having power power, 0 invocations, and a last-touched time later than every stored relic. The weakest contender is the one with the lowest power; among equal power, the fewest invocations; among those, the earliest last-touched time. - If the weakest is a stored relic, remove it, store the newcomer (0 invocations, unsealed, touched), and return the removed relic's name. - If the weakest is the newcomer, nothing changes and name is returned.

With capacity 0, or when every stored relic is sealed, the newcomer is the only contender and is returned.

`invoke(name)`: if stored, its invocation count increases by 1, it is touched, and its power is returned. Otherwise return -1 and change nothing.

`peek(name)`: return the stored relic's power, or -1 if it is not stored. Changes nothing: it is neither a touch nor an invocation.

`seal(name)`: if stored, mark it sealed (permanently; sealing an already sealed relic is allowed) and return true; otherwise return false. Sealing is not a touch. Sealed relics may still be re-stowed and invoked.