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Algorithm & Flowchart

Algorithm & Flowchart. An informal definition of an algorithm is:. Algorithm: a step-by-step method for solving a problem or doing a task. Figure 8.1 Informal definition of an algorithm used in a computer. Algorithm. A step-by-step problem-solving procedure

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Algorithm & Flowchart

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  1. Algorithm & Flowchart

  2. An informal definition of an algorithm is: Algorithm: a step-by-step method for solving a problem or doing a task. Figure 8.1 Informal definition of an algorithm used in a computer

  3. Algorithm • A step-by-step problem-solving procedure • An algorithm is a sequence of unambiguous instructions for solving a problem. • The number of steps of an algorithm will be countable and finite. • It is a sequence of instructions (or set of instructions) to make a program more readable; a process used to answer a question.

  4. Understand the problem. • Define the problem • Analyze the problem • Develop an algorithm/method of solution • Write a computer program corresponding to the algorithm • Test and debug the program • Document the program (how it works and how to use it)

  5. There are two commonly used tools to help to document program logic (the algorithm). These are : • Flowcharts • Pseudo code.

  6. Flowchart A flowchart is a type of diagram that represents an algorithm or process, showing the steps as boxes of various kinds and their order by connecting these with arrows. This diagrammatic representation can give a step-by-step solution to a given problem.

  7. Process operations are represented in these boxes, and arrows connecting them represent flow of control. Flowcharts are used in analyzing, designing, documenting or managing a process or program in various fields.

  8. Symbols • Start and end symbols, represented as lozenges, ovals or rounded rectangles, usually containing the word "Start" or "End", or another phrase signaling the start or end of a process, such as "submit enquiry" or "receive product". • Arrows, showing what's called "flow of control" in computer science. An arrow coming from one symbol and ending at another symbol signifies flow passes to the symbol the arrow points to. • Processing steps, represented as rectangles. Examples: "Add 1 to X"; "replace identified part"; "save changes" or similar. • Input/Output, represented as a parallelogram. Examples: Get X from the user; display X. • Conditional (or decision), represented as a diamond (rhombus). These typically contain a Yes/No question or True/False test .

  9. 1- Simple sequential Flowchart • Example 1: - Read X, Y, Z • Compute Sum (S) as X + Y +Z • Compute Average (A) as S / 3 • Compute Product (P) as X xYxZ - Write (Display) the Sum,Average and Product

  10. • Example 2: Find the sum of two numbers. – Variables: • A: First Number • B: Second Number • C: Sum (A+B) – Algorithm: • Step 1 – Start • Step 2 – Input A • Step 3 – Input B • Step 4 – Calculate C = A + B • Step 5 – Output C • Step 6 – Stop

  11. • Example 3: Find the difference and the division of two numbers and display the result

  12. • Example 4: Find the circle area and circumcenter of a circle where R (radius) is given (exercise) – Variables: • R: Radius • A: Area •C: Circumcenter – Algorithm: • Step 1 – Start • Step 2 – Input R • Step 3 – Calculate Pi • Step 4 – Calculate A = Pi(R)2 • Step 5 – Calculate C = 2Pi(R) • Step 6 – Print R, A, C • Step 7– Stop

  13. 2- Branched Flowcharts • Example 1: Draw a flowchart that shows the traffic light processing (exercise) – Algorithm: • Step 1 – Start • Step 2 – make a Decision (what is the color) • Step 3 – if the color is Red then STOP • Step 4 – if the color is Yellow then WAIT • Step 5 – if the color is Green then PASS • Step 6– Stop

  14. 3- Loop Flowcharts • Example 1:

  15. • Example 2 Average for 10 numbers

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