[Data Structure (Java)] Set

https://crane206265.tistory.com/88

[Data Structure (Java)] Hash (Separate Chaining & Linear Probing)

이번에는 Set입니다. 사실 Hash랑 Map이 재밌긴 했지만 실제로는 Set을 더 많이 쓸거 같은 이 기분..

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Set ADT

: an unordered collection of distinct keys

- elements of a set : unique keys of a map without any associated values

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Set API

API of Set(data type of element : E)

methods	explanation
int size()	return # of elements in the set
boolean isEmpty()	return if the set is empty
boolean add(E e)	add the given element e to the set, return if the set changed
boolean remove(E e)	remove the given element e from the set, return if the set changed
boolean contains(E e)	return if the given element e is in set

 

Java's Set Operations (operations above is also implemented)

methods	explanation
boolean addAll(Collection<E> c)	add all elements from the given collection c to the set, return if the set changed
boolean containsAll(Collection<E> c)	return if all elements from the given collection c is in the set
boolean removeAll(Collection<E> c)	remove all elements from the given collection c from the set return if the set changed
boolean retainAll(Collection<E> c)	remove elements not found in the given collection c from the set return if the set changed
boolean equals(Set<E> s)	return if the given set s and this set is equal
Iterator<> iterator()	return the iterator over the elements in the set
Object[] toArray()	return the array over the elements in the set

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Set Implementation

in java.util package

1. java.util.HashSet : unordered set implementation with a hash table
2. java.util.LinkedHashSet : set implementation with a hash table (in insertion order)
3. java.util.TreeSet : sorted set implementation with a binary tree