Evaluating Solutions in Programming

Topic 8: Evaluating A Solution

• Solution evaluation is crucial after designing, implementing, testing, and debugging a solution.
• Evaluations ensure the quality of the solution.
• Evaluating involves asking basic questions about specific aspects of the solution.

Important Questions About the Solution

• Is it correct?: Does the solution truly solve the problem?
• Is it efficient?: Does the solution use resources reasonably (e.g., time and space)?
• Is it elegant?: Is the solution simple but effective? Is it well-designed?
• Is it usable?: Does the solution provide a satisfactory user experience?

Is It Correct?

• To be correct, a solution must solve the initial problem, regardless of speed or complexity.

• Assume programs are incorrect until proven correct through thorough testing and debugging.

• Correctness is vital in fields like science and law to avoid false positives.

• Proving correctness can involve mathematical proof, but empirical testing is a more common approach in computer science.

• Empirical testing involves carrying out a series of tests to validate the solution. Failure in any test indicates an incorrect solution.

• Testing is an essential part of development. Problem specifications, and tests are prepared in advance.

• The more tests that a solution passes, the stronger the evidence for its correctness.

• A test plan example used vending machines

Is It Efficient?

• Algorithms require resources (time and space) to operate.

• Efficiency measures how well an algorithm uses these resources, evaluated by considering time and space utilization.

• Time: The duration of an algorithm's running time (from start to finish) measured as the number of steps.

• Space: The amount of memory storage an algorithm needs.

• Algorithm efficiency is assessed by analyzing time and space demands.

• Different algorithms solve the same problems using varying efficiency. The 'best' algorithm depends on different factors

• Complexity classes categorize algorithms based on their worst-case performance, indicating how resources would be used in the 'worst' situation for determining how efficiency is measured.

• Table of common complexity classes provided (from O(1) to O(N!)

Is It Elegant?

• Elegant solutions are often challenging to create but deliver significant rewards in terms of both simplicity and effectiveness.

• Elegance considers the depth of understanding of a problem in conjunction with innovative thinking for creating the solution, as simplicity is important

• While different solutions can solve a problem effectively, their elegance might distinguish them.

• Elegance isn't limited to software; it applies to disciplines like engineering, science, and mathematics. An elegant solution maximizes both effectiveness and simplicity.

Is It Usable?

• A solution must provide a positive user experience.
• Correctness, efficiency, and elegance are important but usability is paramount.
• Solutions should be easy to learn, use, and forgiving of errors (user-friendly).
• Usability measures how well a solution allows users to achieve their goals.

Usability components

• Learnability: How easy is it for a user to accomplish basic tasks when they first encounter the solution?
• Efficiency: Once versed with the solution, how efficiently can basic tasks be performed?
• Memorability: Can the solution be efficiently re-learned after some time without consistent use?
• Errors: How many errors do users make and how easily can they recover from them?
• Satisfaction: How pleasant or enjoyable is the solution for the user?

Trade-offs

• Solutions are seldom perfect because of factors like human errors or time constraints.
• Optimizing one aspect can negatively impact another.
• Trade-offs are also often inevitable when trying to optimize many aspects of a solution simultaneously.

This quiz focuses on the importance of evaluating solutions after their design, implementation, testing, and debugging stages. Participants will explore key questions regarding a solution's correctness, efficiency, elegance, and usability to ensure quality outcomes.