Array multiset
= Array multiset
A <multiset> of keys in a fixed finite <integer> range represented by one nonnegative count per key. The <abstraction function> extends the stored <array> counts by zero outside the range. Single-key <additions>, removals and queries use constant <array> work, provided overflow and operation <preconditions> are handled. <Encapsulation> of the count <array> is necessary to preserve its <representation invariant>.