Ch 3- Algorithms

• *WHAT IS AN ALGORITHM*

  An algorithm is a set of instructions for solving a problem or completing a task
• *A GOOD ALGORITHM*

  -          There must be a limited number of steps

  -          The steps must be easy to understand and follow, detailed and specific, clear and unambiguous

  -          Each step should consist of a single task and be at the most basic level that cannot be broken into simpler tasks

  -          All repetitions must have clear ending conditions

  -          There must be at least one result
• *COMPARING ALGORITHMS*

  When we compare algorithms we can reference their precision (how accurately and reliably an algorithm solves a problem) and order (the total number of steps needed to solve a problem)
• *DESIGNING AN ALGORITHMS*     

  • Understand the problem
  • Define the desired solution or output
  • Define the inputs
  • Design a set of steps to complete the task
  • Test the algorithm
  • Update the algorithm
• *FLOWCHARTS*

  • An algorithm is a series of steps to solve a problem or carry out a task
  • A flowchart is a common tool used to help plan and write down the steps needed
• *ARITHMETIC OPERATORS*

  • Addition -> +
  • Subtraction -> -
  • Multiplication -> *
  • Division -> /
  • Exponentiation -> **
  • Integer Division -> div or //
  • Remainder -> mod or %
• *COUNTING AND TOTALLING*

  The statement "count=count + 1" means "Add 1 to the variable (called count)"
• *IPO (INPUT, PROCESS, OUTPUT) TABLES*

  • Input (Variable name and data type)
  • Process (What? and How?)
  • Output (What and Format)
• *TRACE TABLES*

  How to set up?

  Column headers= identify all variables that change their values during the execution of the algorithm

  Rows= each row will represent a point in time or specific step in the algorithms execution