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REVISE EDEXCEL

Edexcel curriculum (2015)


Python

Binary/Hex

Data representation

Compression

Encryption

What is a computer?

Working computer

Hardware

Operating system

Computer processes

The CPU

Memory

Input devices

Output devices

Data storage

Inside the CPU

Stored program

F-D-E cycle

CPU components

Networks

LAN, WAN and PAN

Network topologies

Network addressing

Protocols

Error detection

The internet

The world wide web

HTML and CSS

Client-server model

VPNs

SQL

Impact

Ethical issues

Microcontrollers

Comp models

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Models and sims

Algorithms


Algorithms


 What is an algorithm?

• A precisely stated, step by step list of instructions to carry out a task.

• All algorithms consist of a combination of sequences, selection and repetition.

Is there an algorithm to making a jam sandwich?

Count occurrence

Mark Sheet Scenario
•There are 30 students in a class.
•Each student has taken a test with 20 questions.
•The marks achieved are:
•2, 6, 8, 14, 18, 6, 15, 7, 6, 17, 12, 6, 15, 19, 20, 3, 15, 6, 3, 18, 6, 2, 13, 10, 19, 5, 6, 7, 16, 18.
•How many people gained a mark of 6?
•What process did you go through to work this out?


Picture
PSEUDOCODE

​•SET item TO 0
•SET occurrences TO 0
•SET mark TO 6
•SET list TO [2, 6, 8, 14, 18, 6, 15, 7, 6, 17, 12, 6, 15, 19, 20, 3, 15, 6, 3, 18, 6, 2, 13, 10, 19, 5, 6, 7, 16, 18]
•SET lengthOfList TO 30
•WHILE item <=lengthOfList
–IF list[item-1] == mark THEN
–SET occurrences TO occurrences + 1
–END IF
–SET item TO item +1
•END WHILE
Python challenge

​Above is the psedocode for the algorithm that counts the number of 6s in the list of numbers. Can you write the python code to create a program which counts how many 6s occur? Submit your code using the link at the top right.

Working out the mean

How do you go about working out the mean from the following list of numbers? 2, 6, 8, 14, 18, 6, 15, 7, 6, 17, 12, 6, 15, 19, 20, 3, 15, 6, 3, 18, 6, 2, 13, 10, 19, 5, 6, 7, 16, 18.
Picture
Pseudocode

•SET item TO 1
•SET total TO 0
•SET list TO [2, 6, 8, 14, 18, 6, 15, 7, 6, 17, 12, 6, 15, 19, 20, 3, 15, 6, 3, 18, 6, 2, 13, 10, 19, 5, 6, 7, 16, 18]
•SET lengthOfList TO len(list)
•WHILE item <=lengthOfList
–total = total + list[item-1]
–Increment item by 1
–END WHILE
•MEAN = Total divided by Length of List
•Print Mean
Python challenge

​Above is the pseudocode for the algorithm that works out the mean in the list of numbers. Can you write the python code to create a program which works out the mean? Submit your code using the link at the top right.

A guide that explaies looping through a list can be found here
A guide to help you with the code can be found here

Bubble sort algorithm

The contacts list in our mobile phone is a list that is ordered alphabetically. How does our mobile phones store our contacts in alphabetical order? Bubble sort, sometimes referred to as sinking sort, is a simple sorting algorithm that repeatedly passes  through the list to be sorted. In a single pass, the sorting occurs by a comparison of each pair of adjacent items and swaps them if they are in the wrong order.
Picture
Both this video and and animation show that at any one time, a pair in a list is compared and then change places depending on their size.

Python challenge - Bubble sort

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