Algorithms

Question 1

An algorithm

Answer 1

A series of steps taken to complete a task.

Question 2

Two ways to present algos

Answer 2

Flow charts

Pseudo code

Question 3

Decomposition is

Answer 3

Breaking down on large problem into several smaller sub problems

Question 4

Decomposition advs

Answer 4

Easier for teams to tackle problems

Easier to solve

Question 5

Abstraction

Answer 5

Removal of unecessary details from a problem

Question 6

Abstraction is used in what and advs

Answer 6

Weather models

Makes it less cluttered and easier to see the problem

Question 7

Computational thinking concepts

Answer 7

Algorithmic thinking
Abstraction
Decomposition

Question 8

Algorithm symbols for 
Start/End 
Process 
Input/output 
Decisions

Answer 8

Oval
Rectangle
Parallelogram
Diamond with yes down and no to the side

Question 9

3 basic programming constructs

Answer 9

Sequence
Iteration
Selection

Question 10

Sequence

Answer 10

The order in which execution occurs

Question 11

Selection (pseudocode)

Answer 11

If then else (pseudo code)

Choose between two options

Question 12

Iteration (pseudocode) and types

Answer 12

Repetition of instructions
For loop - definite amount of times action must be repeated eg for 5
Repeat until - indefinite iteration - condition controlled - until it is true wont move on
While loop - action occurs only while the condition is true

Question 13

Two search algorithms are

Answer 13

Linear search

Binary search

Question 14

Linear search is

Answer 14

When data is unsorted, you start at the beginning and search through every item till you find it. Eg
Start at first name
Repeat
Examine current name
IF it’s the one you’re looking for THEN
END IF
UNTIL found = true

Question 15

Binary search is

Answer 15

If the list is sorted in binary or alphabetical order. Repeatedly divide the the data in half till there is only item in the list
Eg
We are trying to find the number 100
We start at fifty
If the number at fifty is lower then we discard everything in the first half and keep on halving the second half till we find it

Question 16

Linear search and binary search advantages and disadvantages

Answer 16

LS is hard for large items cos it will take longer

Binary is quicker but only works on sorted lists

Question 17

Two ways to sort algorithms

Answer 17

Bubble sort

Merge sort

Question 18

Bubble sort is

Answer 18

Repeatedly swapping adjacent elements into the correct order
Eg we want numbers of temp in ascending order it will keep 3&6 the way they are and swap 10& 9.
So from 3 6 10 9
It changes to 3 6 9 10

Question 19

Merge sort

Answer 19

Stage 1 - list is divided in half until each sub list has a length of one
Stage 2 - each pair of sub lists are repeatedly merged to produce new sorted sub lists that then are in order eg
42 31 12 3
Becomes one length long
Then 41 & 31 are swapped & so is 12&3
So 3 12 31 41

Question 20

Compare merge sort and bubble sort

Answer 20

Bubble sort is slow and inefficient for lists that are longer than 3 or 4
Merge sort is a difficult algorithm and hard for inexperienced users