Linear Data Structures

• Array: Fixed-size, index-based. O(1) access.
• Linked List: Dynamic size; each node holds data and a pointer to the next node.
• Stack: LIFO (Last In, First Out). Push and Pop operations. Used in recursion, undo.
• Queue: FIFO (First In, First Out). Enqueue and Dequeue. Used in scheduling.

Non-linear Data Structures

• Tree: Hierarchical. Binary Search Tree: left < root < right.
• Graph: Nodes connected by edges. Directed or undirected.

Sorting Algorithms

• Bubble Sort — O(n²)
• Selection Sort — O(n²)
• Merge Sort — O(n log n)
• Quick Sort — O(n log n) average