2.3 - Algorithms

Question 1

What is a systematic approach to problem solving?

Answer 1

• Reaching a solution by identifying the individual steps required.
• a set of rules allows an algorithm that is followed to be precisely lead to an answer.
• Allows developers to automate solutions.

Question 2

What does abstraction allow?

Answer 2

It allows us to think about what is important and what is not.

Question 3

What 4 steps should you take for a systematic approach?

Answer 3

1. Break the problem down.
2. Think about what data is important or not important.
3. Consider relevent data structures.
4. Tackle each part of the problem step by step.

Question 4

What is an algorithm?

(Simplified)

Answer 4

A sequence of steps followed in order to solve a problem.

Question 5

How does a linear search work?

Answer 5

It starts at the first item in the list and checks each item one by one to find an item in a sorted or unsorted list.

Question 6

What are the 4 characteristics of a linear search?

Answer 6

• Doesn’t require the data set to be in order e.g settings file.
• Can be efficient for smaller data sets.
• Is inefficient for large data sets.
• Easiest searching algorithm to implement but usually the most ineffient.

Question 7

What is a typical use of a linear search?

Answer 7

The find-and-replace function in a word processor.

Question 8

When is an algorithm correct?

Answer 8

If the result is correct for all input instances.

Question 9

What 4 things does a linear search algorithm have to do?

Answer 9

• Be able to locate an item in a data set (if it exists).
• Be able to locate the item regardless of whether the data set is sorted or unsorted.
• Run without crashing even if the item being searched for doesn’t exist in the data set.
• Check each item sequentially, starting with the first item.

Question 10

What is a binary search algorithm?1

Answer 10

An efficient algorithm for finding an item in a sorted data set.
It starts at the middle item in the list and repeatedly divides the list in half.

Question 11

What are the 2 characteristics to be a binary search?

Answer 11

• Requires the data set to be sorted first (e.g. numerical or alphabetical order)
• Is efficient for large data sets.

Question 12

When would you use a binary search?

Answer 12

When you need to search for an item in a large, sorted data set. (e.g. online dictionary in alphabetical order).