Learn: Tracing an Algorithm with a Trace Table

Welcome!You've already learned about algorithms, pseudocode, and how to identify inputs, processes, and outputs. Now let's build on that by exploring how to use a trace table to follow an algorithm step by step.

What is a Trace Table?A trace table is a tool used to track the values of variables as an algorithm runs. It helps you make sure the algorithm works correctly and understand its logic.

Why is a Trace Table Useful?Trace tables are important because they show how data changes at each step of the algorithm. This helps you identify errors and understand how the algorithm solves the problem.

How to Create a Trace TableTo create a trace table, follow these steps:Write the algorithm in pseudocode or code.Identify all variables in the algorithm.Create a table with columns for each variable and rows for each step.Fill in the table as you follow the algorithm step by step.

Example AlgorithmLet's look at a simple algorithm: Add all numbers in a list. The pseudocode is:sum = 0for each number in list: sum = sum + numberend forWe'll use a trace table to follow this algorithm step by step.

Using a Trace TableWhen using a trace table, follow these steps:Start with the initial values of variables.Update the values step by step as the algorithm runs.Check for errors or unexpected results.

Trace Table ExampleHere's a trace table for the algorithm above:List = [2, 4, 6]Step: StartVariables: sum = 0Step 1: Add 2Variables: sum = 2Step 2: Add 4Variables: sum = 6Step 3: Add 6Variables: sum = 12The sum variable updates as we process each number in the list.

Review Time!Great work! You've learned what a trace table is, why it matters, and how to use one. Let's test your understanding with a few questions.