G4G0-2/Data Structures/GPT Answers to Past Paper/Question 2.md

Describe a scenario where a stack data structure would be more suitable than a Queue

A stack data structure is more suitable than a queue in scenarios where you need to process items in a Last-In, First-Out (LIFO) order

Scenario: Undo Operation in Text Editors

• Description: In text editors, when a user types, deletes, or performs other actions, these operations are stored so they can be undone in reverse order of execution.
• Why a Stack?:
  • The most recent action (the "last-in") is the first one that should be undone (the "first-out").
  • A stack efficiently tracks these operations, allowing actions to be added to the stack as they occur and popped off when the user undoes them.
• How It Works:
  1. User types "Hello" → each character is pushed onto the stack.
  2. User presses "Undo" → the stack pops the last character added.

Scenario: Call Stack in Recursion

• Description: When a program uses recursion, the function calls are nested, and each call must finish before the previous one can resume.
• Why a Stack?:
  • The current function (most recent call) must finish execution (be "popped" off the stack) before the previous function call can resume.
  • The stack keeps track of the state and local variables for each function call.
• How It Works:
  1. Function A calls B, which calls C.
  2. The stack stores the execution state of A, then B, then C (last-in).
  3. When C finishes, its state is removed (first-out), resuming B.

Scenario: Browser Backtracking

• Description: When navigating a web browser, the "Back" button relies on a stack to revisit the most recently visited page.
• Why a Stack?:
  • The most recent page (last-in) should be revisited first (first-out) when the user clicks "Back".
• How It Works:
  1. User navigates to pages: A → B → C. Each page is pushed onto the stack.
  2. Clicking "Back" pops the stack, returning to page B, then A.

Key Contrast with a Queue:

• A queue is more suitable when processing items in a First-In, First-Out (FIFO) order, such as serving customer requests or scheduling tasks.
• A stack is better when you need reversal or to process the most recent element first, such as undo operations, recursion, or browser backtracking.

Describe a scenario where a stack data structure would be more suitable than a
Queue