Data Structures: Arrays and Linked Lists

Study Notes

Data Structures

Data structures are specialized formats for organizing, processing, retrieving, and storing data. They serve as the blueprint for how data is managed in a program.
Choosing the right data structure is vital for optimizing program performance in terms of speed and memory usage.

Arrays

Arrays are contiguous blocks of memory that store elements of the same data type.
Accessing elements is very fast (O(1) time complexity) because the position of an element is known directly.
Insertion and deletion can be slow (O(n) time complexity) if the elements need to be shifted.
Arrays are useful when the size of the data is known in advance.
Fixed size arrays store a predetermined number of elements and must be declared with a specific size.
Can be used for storing sequential data.

Linked Lists

Linked Lists are dynamic data structures where elements are not stored contiguously.
Each element (node) contains data and a pointer to the next node in the sequence.
Insertion and deletion are generally faster (O(1) time complexity) since only the pointers need to be adjusted.
Accessing elements requires traversing the list from the beginning, which can be slow (O(n) time complexity).
Memory allocation happens dynamically as needed.
Singly linked lists have pointers that traverse only forward; doubly linked lists contain pointers in both directions.

Stacks

Stacks are linear data structures that follow the Last-In, First-Out (LIFO) principle.
Elements are added (pushed) and removed (popped) from the top of the stack.
Common operations include push, pop, peek (view the top element), and isEmpty.
Stack implementations are often found using arrays or linked lists.
Stacks are used in function calls, undo/redo mechanisms, expression evaluation, and backtracking algorithms.
A stack overflow occurs when you try to push an element onto a full stack.

Trees

Trees are hierarchical data structures with a root node and child nodes.
Each node can have zero or more child nodes.
Different types of trees exist, including binary trees, binary search trees, and heaps.
Binary trees limit each node to at most two children.
Binary search trees maintain an order where values in left subtrees are smaller than the parent, and right subtrees values are larger.
Trees are used in representing hierarchical data like file systems, organizational charts, and expression parsing.
Efficient searching, insertion, and deletion are often possible in certain types of trees.
Tree traversals (inorder, preorder, postorder) provide systematic ways to visit all nodes.

Key Differences

Arrays: Fast access, fixed size, contiguous memory allocation.
Linked Lists: Dynamic size, slower access, non-contiguous memory allocation.
Stacks: LIFO order, efficient for function calls, undo/redo.
Trees: Hierarchical data representation, efficient for searching/sorting in certain types.

Description

This quiz covers the fundamentals of data structures, focusing specifically on arrays and linked lists. You'll learn about their characteristics, advantages, and performance implications. Test your understanding of how these structures manage data in programming.