Itty Bits

Question 1

byVal vs byRef:

Answer 1

By value: A copy of the value is passed.
By reference: The address of the parameter is given so it will be updated at the given address.

Question 2

Local variables vs global variables

Answer 2

Local variables:
+ Ensures subroutines are self contained
+ Requires less memory

Global variables:
- Can be unintentionally overwritten
- Take up more storage

Question 3

Recursive methods advantages and disadvantages

Answer 3

+ Efficient use of code
+ Tail recursion: Less space is required
- If it calls itself too many times, that could result in stack overflow, causing a crash
- Difficult to trace

Question 4

Concurrency advantages and disadvantages:

Answer 4

Each task is given a slice of processor time
+ Number of tasks is increased
+ Less time wasted waiting for an input, as other tasks can be completed
— Can take longer to complete when there’s a large number of users and tasks
— Not all tasks are suited to being broken up and performed correctly

Question 5

What does abstraction do?

Answer 5

Hides information that is too complex or irrelevant to the systems purpose
Enables more efficient software design
Reduces time spent on project

Question 6

Modular programming

Answer 6

Splitting tasks into smaller moduals.
Top down approach:
Continually broken down into sub-problems, which each can be represented as single task

Question 7

Backtracking

Answer 7

Methodically visiting each path, and if a path is found to be invalid, bacingtracking to the previous stage and visits an alternate path
Example: Depth-first traversals

Question 8

Quick Sort

Answer 8

Selects a central element called a pivot
Elements smaller than the pivot are placed on the left (as close to the centre as possible, working through from the centre outwards), and elements larger are placed on the right.
This process repeats recursively on each new list until all elements in the lists are old pivots or have a length of 1
Old pivots are ignored
Pivot reads from centre outwards

Question 9

Merge Sort Tip

Answer 9

The parts are called elements

Question 10

Binary Search Tip

Answer 10

Biases to the right

Question 11

Depth-First Traversal

Answer 11

Same as post-order
Goes as far down into the tree as possible before backtracking
Uses a stack

Question 12

Breadth-First traversal

Answer 12

Uses a queue

Question 13

Decomposition defintion

Answer 13

Breaking down the problem into smaller solutions

Question 14

Decomposition benefits:

Answer 14

+ Easier to manage
+ Development teams can be deployed
+ Parts can be worked in parallel
+ Easier to locate errors within specific moduals
+ Without it, testing would have to be done all at once.