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IB Computer Science: B4 · Abstract data types (HL)

Stacks, queues, linked lists, trees. 1 subtopics, 5 key terms.

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In this topic: B4.1

B4.1Abstract data types HL

Abstract data type (ADT): A data type defined by its behaviour (operations), not its implementation.
Stack: LIFO: push adds to the top, pop removes from the top.
Queue: FIFO: enqueue adds to the rear, dequeue removes from the front.
Linked list: Nodes containing data and a pointer to the next node.
Binary search tree (BST): Each node's left subtree has smaller values and right subtree larger values.

Stack uses: undo, call stack, backtracking, evaluating expressions. Queue uses: print queues, task scheduling, breadth-first search.

The full notes, worked example, interactive diagram and check questions for this subtopic are in the app.

Exam tip: Draw the structure step by step: questions often ask for the state after a sequence of operations.