Pseudo Code: Algorithm Design and Problem Solving

Pseudo Code Video: Algorithm Design and Problem Solving

• Explains the purpose of a given algorithm and understanding standard methods of solution.
• Includes input and output, totaling and counting.
• Covers how standard flowchart symbols are used.

Pseudo Code Recap

• Shows an algorithm using English keywords similar to high-level programming languages.
• Data items are given meaningful names like variables and constants.
• Not bound by strict syntax like programming languages.
• Example calculates the average grade for 10 students.
• Average grade written in standard English as a list of items.

Input and Output

• Input is entry of data into the program.
• Output is getting information on screen or printing on paper.
• "Read" can be used instead of "input".
• "Print" can be used instead of "output".

Explaining Algorithm Purpose

• Provides steps to complete a task.
• Similar to a recipe for baking a cake, it is often made of list of instructions.
• Can be shown as a flowchart or pseudo code.
• The purpose of the task and processes must be clear; practice helps with error correction.
• Example outputs an alarm sound at a set time.
• Processes involve waiting, getting the current time, and comparing it to the alarm time.
• The alarm sound outputs when times match.
• Value 7 am assigned to the alarm time, an mp3 music file assigned to alarm sound
• The pseudo code repeats waiting for 10 seconds and getting time until current time is 7 AM.

Flowcharts and Pseudo code

• Algorithm takes input number one with value of 9 or input number two with value of 21.
• If number one (9) is greater than number two (21) is tested as some form of condition.
• The flowchart outputs "number two is the largest" or "21 is the largest", and then stops.
• The pseudo code replicates said process.

Standard Methods of Solution (IGCSE)

• Repeat existing methods to find the correct solutions.
• When an algorithm is a program, steps can be repeated thousands of times.
• Include: totaling, counting, max/min/mean values, searching (linear), and sorting (bubble sort).

Totaling

• Keeps a running total of values being added.
• For example marks awarded to students in a class.
• Assigns zero to the value of "total" at start.
• A "for" loop assigns one to the class size.
• "Total" is assigned the "total" plus the "student grade" to add to the running total.
• The marks are totaled in a variable called "student grade."

Counting

• Keeping count of when an action occurs is a standard method.
• For example, counting students awarded a passing grade.
• Initialize a "pass count" variable to zero as we start.
• Increment the "pass count" whenever a student's grade is over a defined amount.
• pass count = pass count + 1

Max, Min, and Average

• Finding the largest and smallest values in a list are standard methods.
• Used in algorithms to discover the highest and lowest mark awarded to a student.
• Set max to zero and min to 100 and loop through all student grades.
• If student grade is greater than the max, set max to the current student grade, same for min.

Linear Search

• Simplest way of searching through an array of list of items.
• It goes through to locate the new element by comparing it to others sequentially.
• Used when searching list of student names.
• "Found" is set to "false" initially, acting as a flag (true or false if name has been found).
• The counter is set to one.
• The algorithm repeats: if the name equals a student name in the list, then "found" is true, and add one to the counter.
• Every time a correct name is found, the flag is true.

Bubble Sort

• Multiple sorting methods exist (names alphabetical, temperatures ascending/descending).
• Involves different types of sorts.
• Focus is on a list of numbers sorted to ascending order (lowest to highest).
• Start at the first element of the array and compare the first and second elements.
• If the first element is greater than the second, elements are swapped.
• This process continues until the last element.