Problem Solving in Computer Science

Problem Solving

• Problem solving is a process to define a problem and create solutions.
• The process starts with the problem specifications and ends with a working program.

Problem Solving Techniques

• Problem solving techniques are methods to provide logic for solving a problem.
• Algorithms, flowcharts, pseudo code, and programs are all representations of problem solving techniques.

Algorithm

• An algorithm is a sequence of instructions that describes a method for solving a problem.
• It's a step by step procedure for solving a problem.
• Properties of algorithms:
  • Written in clear English.
  • Instructions are unambiguous.
  • No infinite repetition of instructions.
  • Finishes in a finite number of steps.
  • Has a clear end point.
  • Results are obtained only after algorithm termination.

Qualities of a Good Algorithm

• Time: The time it takes to execute a program. Less time is better.
• Memory: The amount of computer memory a program uses. Less memory is better.
• Accuracy: Some algorithms may provide more accurate results than others for the same problem.

Example Algorithm: Print "Good Morning"

• Start
• Print "Good Morning"
• Stop

Building Blocks of Algorithms

• Algorithms are built from three basic blocks:
  • Sequence
  • Selection
  • Iteration

Statements

• A statement represents a single action in a program.
• Examples of statements include:
  • Inputting data (providing information to the program)
  • Processing data (performing operations on the input)
  • Outputting data (displaying the processed result)

State

• A state is a transition from one process to another process under a specific condition within a given time.

Control Flow

• Control flow is the order in which statements are executed.
• Three types of control flow:
  • Sequence
  • Selection
  • Iteration

Sequence

• Instructions are executed one after another.

Example: Add Two Numbers

• Start
• Get two numbers, a and b
• Calculate c = a + b
• Display c
• Stop

Selection

• A selection statement allows the program to execute different parts of code based on a condition.
• If the condition is true, one part of the code is executed.
• If the condition is false, a different part of the code is executed.

Example: Check Voter Eligibility

• Start
• Get the user's age
• If the age is greater than or equal to 18, print "Eligible to vote"
• Otherwise, print "Not eligible to vote"
• Stop

Iteration

• Iteration, or looping, executes a set of statements repeatedly based on a condition.
• These set of statements are executed more than one time.

Example: Print Natural Numbers Up To N

• Start
• Get the value of n
• Initialize i = 1
• While (i <= n)
  • Print i
  • Increment i by 1
• Stop

What is not Included in the Summary:

• The text also discusses notation such as pseudo code, flowcharts, and programming language.
• It also covers simple strategies for developing algorithms like iteration and recursion.
• This information is not included in the summary to keep it concise.

This quiz covers foundational concepts in problem solving, including techniques and algorithms. Learn about the qualities of a good algorithm and how to effectively define and solve problems using structured methods. Test your knowledge of key principles that guide the programming process.