IB Computer Science Topic D.4.10 ADT Stack, Queue, and Binary Tree Features Revision Notes (SL/HL)

IB Computer Science Topic D.4.10 ADT Stack, Queue, and Binary Tree Features Revision Notes (SL/HL) | RevisionDojo

ADT Stack, Queue, and Binary Tree Features

Stacks

A stack is a fundamental abstract data structure that operates on a LIFO principle.

Definition

LIFO

Last-in, First-out principle.

This means that the last element added to the stack is the first one to be removed.

Analogy

Note

A stack is like a stack of plates.
You can only add or remove the top plate, which makes it easy to manage but limits access to other plates.

Example

Key Characteristics of a Stack

LIFO Order: Elements are added and removed from the top of the stack.
Limited access: Only the top element is accessible at any given time.
Dynamic size: Stacks can grow or shrink depending on the implementation (linked list) or have a fixed size (array).

Core Operations of a Stack

Push: Adds an element to the top of the stack.
Pop: Removes and returns the top element of the stack.
Peek (or Top): Returns the top element without removing it.
isEmpty: Checks if the stack is empty, returning true or false..

Note

In IB's official pseudocode, stacks have methods:

push()
pop()
isEmpty()

Example

Note

Recursive functions use the call stack, a special stack in memory, to keep track of function calls and their local variables:

Stacks are used to store return addresses when a function is called.
This ensures that the program can return to the correct location after the function completes.
When a function is called, its return address and local variables are pushed onto the stack.
When the function returns, these are popped off, restoring the previous state.

You can experiment with call stacks on websites like pythontutor.com.

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Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

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Note

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Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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ADT Stack, Queue, and Binary Tree Features

Stacks

A stack is a fundamental abstract data structure that operates on a LIFO principle.

Definition

LIFO

Last-in, First-out principle.

This means that the last element added to the stack is the first one to be removed.

Analogy

Note

A stack is like a stack of plates.
You can only add or remove the top plate, which makes it easy to manage but limits access to other plates.

Example

Key Characteristics of a Stack

LIFO Order: Elements are added and removed from the top of the stack.
Limited access: Only the top element is accessible at any given time.
Dynamic size: Stacks can grow or shrink depending on the implementation (linked list) or have a fixed size (array).

Core Operations of a Stack

Push: Adds an element to the top of the stack.
Pop: Removes and returns the top element of the stack.
Peek (or Top): Returns the top element without removing it.
isEmpty: Checks if the stack is empty, returning true or false..

Note

In IB's official pseudocode, stacks have methods:

push()
pop()
isEmpty()

Example

Note

Recursive functions use the call stack, a special stack in memory, to keep track of function calls and their local variables:

Stacks are used to store return addresses when a function is called.
This ensures that the program can return to the correct location after the function completes.
When a function is called, its return address and local variables are pushed onto the stack.
When the function returns, these are popped off, restoring the previous state.

You can experiment with call stacks on websites like pythontutor.com.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

1. System fundamentals2 subtopics

2. Computer organization1 subtopic

3. Networks1 subtopic

4. Computational thinking, problem-solving and programming3 subtopics

5. Abstract data structures (HL)1 subtopic

6. Resource management (HL)1 subtopic

7. Control (HL)1 subtopic

A. Databases4 subtopics

B. Modelling and simulation4 subtopics

C. Web science6 subtopics

D. Object-oriented programming (OOP)4 subtopics

IB Computer Science D.4.10 ADT Stack, Queue, and Binary Tree Features Notes

1. System fundamentals2 subtopics

2. Computer organization1 subtopic

3. Networks1 subtopic

4. Computational thinking, problem-solving and programming3 subtopics

5. Abstract data structures (HL)1 subtopic

6. Resource management (HL)1 subtopic

7. Control (HL)1 subtopic

A. Databases4 subtopics

B. Modelling and simulation4 subtopics

C. Web science6 subtopics

D. Object-oriented programming (OOP)4 subtopics

ADT Stack, Queue, and Binary Tree Features

Stacks

Key Characteristics of a Stack

Core Operations of a Stack

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

ADT Stack, Queue, and Binary Tree Features

Stacks

Key Characteristics of a Stack

Core Operations of a Stack

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account