Data Structures

Using Java Framework

Queue #

Set #

HashMap (or Map Interface) #

• Description: A collection that stores key-value pairs, providing constant-time complexity for insertions, deletions, and lookups.
• Java Implementation:

Example:

HashMap<String, Integer> map = new HashMap<>();

• Use Cases: Frequently used for scenarios requiring fast lookups by a key, like counting frequencies of elements or caching.

5. HashSet (or Set Interface) #

• Description: A collection that stores unique elements with no duplicate values and provides constant-time operations.
• Java Implementation:

Example:

HashSet<Integer> set = new HashSet<>();

• Use Cases: Efficient for checking the existence of an element in a collection.

7. Queue #

• Description: A first-in-first-out (FIFO) data structure where the first element added is the first one to be removed.
• Java Implementation:

Example:

Queue<Integer> queue = new LinkedList<>();

• Use Cases: Task scheduling, breadth-first search (BFS), etc.

9. Tree (Binary Tree, Binary Search Tree) #

• Description: A hierarchical data structure where each node has a value and pointers to child nodes.
• Java Implementation: Custom implementations for Binary Tree or Binary Search Tree.
• Use Cases: Efficient searching, sorting, hierarchical data representation, etc.

10. Trie #

• Description: A tree-like data structure used to store dynamic sets of strings, where each node represents a character.
• Java Implementation: Custom implementation is typically required.
• Use Cases: Autocomplete, dictionary implementations, and prefix-based searches.

11. Graph #

• Description: A data structure consisting of nodes (vertices) and edges that connect pairs of nodes.
• Java Implementation: You can implement graphs using an adjacency list, adjacency matrix, or edge list.
• Use Cases: Modeling relationships, networks, pathfinding algorithms (BFS, DFS, Dijkstra), etc.

13. LinkedHashMap #

• Description: A HashMap that maintains the insertion order.
• Java Implementation:

Example:

LinkedHashMap<String, Integer> lhm = new LinkedHashMap<>();

• Use Cases: Useful when you need to maintain the order of entries while performing fast lookups.

14. TreeMap #

• Description: A Red-Black tree-based implementation of Map that keeps keys in sorted order.
• Java Implementation:

Example:

TreeMap<String, Integer> treeMap = new TreeMap<>();

• Use Cases: When you need sorted key-value pairs.

15. BitSet #

• Description: A special array-like data structure that efficiently stores bits.
• Java Implementation:

Example:

BitSet bitSet = new BitSet();

• Use Cases: Storing and performing operations on bits like flags, bloom filters, etc.

16. EnumSet #

• Description: A specialized Set for use with enum types.
• Java Implementation:

Example:

EnumSet<Day> days = EnumSet.of(Day.MONDAY, Day.WEDNESDAY);

• Use Cases: Handling sets of enums, particularly in situations where performance matters.