Fundamentals of Algorithms

Question 1

Understand and explain the term algorithm

Answer 1

An algorithm is a sequence of steps that can be followed to complete a task

Question 2

Understand and explain the term decomposition

Answer 2

Breaking a problem into a number of sub-problems, so that each sub- problem accomplishes an identifiable task, which might itself be further subdivided

Question 3

Understand and explain the term abstraction

Answer 3

the process of removing unnecessary detail from a problem

Question 4

Understand and explain how the linear search algorithm works.

Answer 4

Goes through the list checking each element until it has found a match

Question 5

Understand and explain how the binary search algorithm works.

Answer 5

Continues dividing list into 2 until element is found. Has to be in order

Question 6

Understand and explain how bubble sort works.

Answer 6

Swaps the elements until they are in order

Question 7

Understand and explain how merge sort works.

Answer 7

DIVIDE, CONQUER AND COMBINE

Question 8

Advantages and disadvantages of the searches

Answer 8

Linear is much more simpler but binary is more efficient. Linear can be used on any type of list, even unordered, usually smaller ones. Binary can only be used on ordered lists, takes fewer steps so can be used on larger lists

Question 9

Compare and contrast merge sort and bubble sort algorithms

Answer 9

Bubble sort: Easily implemented on a computer, efficient way to check if list is already in order. Doesn’t use much memory.
Inefficient way to sort a list, does not cope well with a very large list.
Merge sort: More efficient and quicker than bubble sort for large lists, very consistent running time.
Slower than other algorithms for smaller lists, uses more memory

Question 10

Understand the concept of a data type

Answer 10

A means of classifying different data. Determines what operations can be conducted and how the data will be stored.

Question 11

What is casting?

Answer 11

Changing the data type

Question 12

What is a sequence, iteration and selection?

Answer 12

Sequence - all lines executed
Selection - decisions made that determine the execution
Iteration - code repeated until specified conditions met

Question 13

What is a variable?

Answer 13

References to locations in the memory containing single values

Question 14

What is a constant?

Answer 14

Identifier that are associated with values that remain fixed during the programs execution

Question 15

Why are constants and variables used?

Answer 15

They are easier to read by making the code more clear. and have a better ability to update as you only need to update the initial value once

Question 16

What is a subprogram?

Answer 16

An “out of line” block of code that performs a specific task

Question 17

Advantages of subprogram

Answer 17

Saves time when there is a pattern in a codecan be either user-written or pre-existing

Question 18

What is a local variable?

Answer 18

Variables that are only declared inside a function and are local to that subroutine

Question 19

Explain why it is good practice to use local variables?

Answer 19

You can use multiple variables with the same name in a program as they take precedence over variables with the same name

Question 20

Describe the structured approach to programming

Answer 20

The three controls should have a single entry and exit and the problem should be decomposed into specific, sea-contained and independent modules.
Independent subroutines should not be reliant of global variables as data should be passed through parameters and there should be indentations.