AS5

Question 1

Data Structure

Answer 1

• A data structure is a collection of related items held together in memory.

Question 2

Static Structures

Answer 2

• Size is set at beginning of program.
• Size cannot be changed.
• Inefficient use of memory.
• Easy to program.
• Programmer will know how much space they take up.

Question 3

Dynamic Structure

Answer 3

• Size is not set.
• Can expand or shrink as needed.
• Efficient use of memory.
• Harder to implement (need to keep track of size.)
• Not held in contiguous memory. (Each element contains pointer to next element.)

Question 4

Array

Answer 4

An array stores a sequence of variables that are all of the same type, grouped under one identifier.
- Normally static.
- Individual values are indexed.
- Can be multidimensional.
- Holds elements of the same type.
- Can iterate through.

Question 5

List

Answer 5

• A list is dynamic as its size can change on execution.
• New elements can be easily added and removed by changing pointers.

Question 6

Two-Dimensional Array

Answer 6

• Visualised as a grid with rows and columns.
• An array of arrays.
• The position of an element is referred to by two indices rather than one.
• In Python, each element can be accessed by using a nested loop.

Question 7

Searching an array

Answer 7

• Arrays are usually immutable (can’t increase their size once created).
• It isn’t possible to remove elements, but you can set them as null.
• Then search for empty spaces and put new data there.

Question 8

Records

Answer 8

• A set of items all related to a single entity.
• May contain items of more than one data type.
• Can be multidimensional.
• Fixed size.
• Cannot iterate through a single record.

Question 9

Dictionaries

Answer 9

• Used to create record structures in Python.
• Consists of two objects: a key and values.
• The key identifies the element, the value is the corresponding data.
• The key is unique.