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A set is an abstract data type representing an unordered collection of unique elements. Sets behave like maps , but only store a single value (analogous to the key in a map), rather than mapping a key to another value.

Common operations

Name Description
size() gets the number of elements in the set
contains(e) returns whether element e is contained in the set
add(e) adds element e to the set
remove(e) removes element e from the set, if it exists

Sets are commonly implemented using hash tables or binary search trees , since they facilitate rapid lookup for unordered collections of data.