TMC 1414 Introduction to Programming

TMC 1414 Introduction to Programming
Lecture 02: Problem Solving & Algorithms

Problem Solving??

We will learn about: What is Problem Solving? How to solve a problem?
Problem Solving Strategies Solving problem with computer -Software Development Method of Problem Solving Steps in the Software Development Method Design & representation of algorithms Programming errors & debugging Program verification & testing Flowchart & Pseudocode

What is Problem Solving?
Definition: Problem solving is the process of transforming the description of a problem into the solution of that problem by using our knowledge of the problem domain and by relying on our ability to select and use appropriate problem solving strategies, techniques and tools.

Problem Faced in Everyday in Life
People make decisions everyday Examples: Should I wear casual or formal today? Should I watch TV or go out to cinema? Where is my what c programming lab? What is the course code? Where to put my bag? Everything needs a DECISION AS A SOLUTION TO THE PROBLEM

Steps to solve a problem
Step 1: Identify the problem Step 2: Determine the problem solving strategy to apply Step 3: Design the solution Step 4: Execute the solution Step 5: Evaluate the successfulness of the solution

Problem Solving Strategies
Many strategies can be use in solving problem. Most popular type of strategy is the “Art of War” by Sung Zhi (Ancient Chinese Philosopher) We will learn: Guess and Check (Try an Error) Start at the end (Work Backward) Divide and Conquer Look for a Pattern

Guess and Check (Try an Error)
Simplest strategy available. Just experimenting with the possible solution. A bit time consuming if have a lot of possible solution But it is very efficient and practical for solving small or medium problem Example Prince A divided 15 stone games into two piles: games he owns and games his brother owns. He owns 3 more games than his brother. How many games does his brother own?

Solution I'll guess his brother owns 8 games.
That means Prince Carl owns 11 games. That's a total of 19 games. My guess is too high. I'll guess again. This time I'll guess his brother owns 6 games. That means Prince Carl owns 9 games. That's a total of 15 games. My guess is right. His brother owns 6 games.

Start at The End (Working Backward)
Sometime to solve some problem, you may need to undo some of the key actions in the problem. Also known as bottom-up approach Example: The castle kitchen servants brought in 4 pies left over from the feast. 12 pies were eaten at the feast. Queen Mab took 2 home with her. How many pies did the servants bring into the feast at the beginning?

Solution First, I'll account for all the pies that were eaten or taken home. = 14 Then I'll add the 4 pies that were left over. Therefore, there must have been 18 pies at the start of the feast.

Divide and Conquer Most popular strategy used in problem solving.
Used by Napoleon in his quest to conquer the world. Often break up large problems into smaller units that are easier to handle.

Look for a pattern More advance way to solve a complicated problem
Some problem can be solved by recognizing pattern within the domain. For example: Daniel arranged loaves of bread on 6 shelves in the bakery. He put 1 loaf on the top shelf, 3 loaves on the second shelf, and 5 loaves on the third shelf. If he continues this pattern, how many loaves did Daniel put on the 6th shelf?

Solution Shelf 1 2 3 4 5 6 Loaves 7 9 11

Other Strategies TIPs:
Drawings/modeling Logical Reasoning Extra Information TIPs: Strategy is only to help you to solve problem. Most important thing is keep youR mind cool and try to find ways to overcome the difficulties!!

Problem Solving Strategies…
GET READY FOR . . . Problem Solving Strategies…

TAKS BASED PROBLEM SOLVING MODEL
Read the problem. Understand the problem. Make a Plan. Carry out the plan. Solve

Julia has 5c. Her brother gave her 3c
Julia has 5c. Her brother gave her 3c. How much money does she have in all?

Julia has 5c. Her brother gave her 3c. How much money does she have in all? Julia

Julia has 5c. Her brother gave her 3c. How much money does she have in all? Julia C C C C C

Julia has 5c. Her brother gave her 3c. How much money does she have in all? brother Julia C C C C C

Julia has 5c. Her brother gave her 3c. How much money does she have in all? brother Julia C C C C C C C C

Julia has 5c. Her brother gave her 3c. How much money does she have in all? brother 5 + 3 ------ 8 Julia has 8 cents in all. Julia C C C C C C C C

Dallas collected 8 marbles. Edna collected 6 marbles
Dallas collected 8 marbles. Edna collected 6 marbles. How many more marbles did Dallas collect than Edna?

Dallas collected 8 marbles. Edna collected 6 marbles. How many more marbles did Dallas collect than Edna? Dallas

Dallas collected 8 marbles. Edna collected 6 marbles. How many more marbles did Dallas collect than Edna? Dallas M M M M M M M M

Dallas collected 8 marbles. Edna collected 6 marbles. How many more marbles did Dallas collect than Edna? Edna Dallas M M M M M M M M

Dallas collected 8 marbles. Edna collected 6 marbles. How many more marbles did Dallas collect than Edna? Edna Dallas M M M M M M M M M M M M M M

Dallas collected 8 marbles. Edna collected 6 marbles. How many more marbles did Dallas collect than Edna? Dallas collected 2 more marbles than Edna. 8 - 6 ------ 2 Edna Dallas M M M M M M M M M M M M M M

Elia baked 7 cookies. Fred baked 2 cookies. Elia gave 2 cookies to Fred. How many cookies does Elia have now?

Elia baked 7 cookies. Fred baked 2 cookies. Elia gave 2 cookies to Fred. How many cookies does Elia have now? Elia C C C C C C C

Elia baked 7 cookies. Fred baked 2 cookies. Elia gave 2 cookies to Fred. How many cookies does Elia have now? Fred Elia C C C C C C C

Elia baked 7 cookies. Fred baked 2 cookies. Elia gave 2 cookies to Fred. How many cookies does Elia have now? Fred Elia C C C C C C C C C

Elia baked 7 cookies. Fred baked 2 cookies. Elia gave 2 cookies to Fred. How many cookies does Elia have now? Fred Elia C C C C C C C C C C C

Elia baked 7 cookies. Fred baked 2 cookies. Elia gave 2 cookies to Fred. How many cookies does Elia have now? Fred Elia has 5 cookies now. 7 2 ---- 5 Elia C C C C C C C C C C C

Solving Problem with Computer
Computers use algorithmic solutions: Program – set of instructions that make up solution to a problem Results – outcome of running the program Testing – Are the outcomes what we expected and correct Documentation -manual documentation – instructions telling users how to use the program

Problem solving with computers involves several steps
Clearly define the problem. Analyse the problem and formulate a method to solve it. Describe the solution in the form of an algorithm. Draw a flowchart of the algorithm. Write the computer program. Compile and run the program (debugging). Test the program (debugging) (see also verification.). Interpretation of results.

Thus, we use software development method which consists of the following steps:
Requirement specification Analysis Design Implementation Testing and verification Documentation

Solving a Problem VS Developing a program
Steps to solve problem Software Development Method Step 1: Identify the problem Step 1: Requirement specification Step 2: Identify the possible solution and determine the best applicable solution Step 2: Analysis Step 3: Design the solution Step 3: Design Step 4: Execute the solution Step 4: Implementation Step 5: Evaluate the successfulness of the solution Step 5: Testing and verification Step 6: Documentation

Basic Steps in Software/Application Development
Requirement Specification Analysis Design Implementation & Deployment Testing Documentation

Requirement Specification
A task to determine the needs and conditions (including scope) to meet in the new system Requirements can be obtains through several methods Brainstorming session Survey Interview Observation others

Analysis After obtaining the requirements, then the software developer need to study the approach/ method to solve the problem. Using different problem techniques Determine best solution from given options

Design A crucial phase before the actual coding process
Several thing need to be consider during the design of a application or software Compatibility Extensibility Reliability Reusability Robustness Usability

Designing software usually is designing an Algorithm.
An Algorithm is a sequence of a finite number of steps arranged in a specific logical order, which, when executed, produce the solution for a problem.

An algorithm must satisfy some requirements:
Unambiguousness It must not be ambiguous. Computers cannot cope with ambiguous. Therefore, every step in an algorithm must be clear as to what it is supposed to do and how many times it is expected to be executed.

Generality Correctness Finiteness It must have generality.
A procedure that prints the message “One inch is cm” is not an algorithm; however, one that converts a supplied number of inches to centimeters is an algorithm. Correctness It must be correct and must solve the problem for which it is designed. Finiteness It must execute its steps and terminate in finite time. An algorithm that never terminates is unacceptable.

Something to ponder … What is the connection between the real life processes and algorithm?

Algorithm A specific and step-by-step set of instructions for carrying out a procedure or solving a problem, usually with the requirement that the procedure terminate at some point 2 types of algorithm representation will be explained: Flowchart Pseudocode

Pseudocode a semiformal, English-like language (or other language that can be understand by human being) limited vocabulary that can be used to design and describe algorithms. Not executed on computers A carefully prepared pseudocode program may be converted easily to a corresponding C program

Pseudocode A pseudocode can be used for:
Designing algorithms Communicating algorithms to users Implementing algorithms as programs Debugging logic errors in program Documenting programs for future maintenance and expansion purposes A pseudocode must meet these requirements: Have a limited vocabulary Be easy to learn Produce simple, English-like narrative notation Be capable of describing all algorithms, regardless of their complexity

How to write Pseudocode
An algorithm can be written in pseudocode using six (6) basic computer operations: A computer can receive information. Typical pseudocode instructions to receive information are: Read name Get name Read number1, number2

A computer can output (print) information. Typical pseudocode instructions are: Print name Write "The average is", ave A computer can perform arithmetic operation Typical pseudocode instructions: Add number to total Total = Total + Number Ave = sum/total

A computer can assign a value to a piece of data: To assign/give data an initial value: Initialize total to zero Set count to 0 To assign a computed value: Total = Price + Tax

A computer can compare two (2) pieces of information and select one of two alternative actions. Typical pseudocode e.g. If number < 0 then add 1 to neg_number else add one to positive number end-if

A computer can repeat a group of actions. Typical pseudocode e.g. Repeat until total = 50 read number write number add 1 to total end-repeat OR while total < = 50 do: end-while

Example of pseudocode Start Read status end if status is equal to 1
print “on” Else If status is equal to 0 print “ Off” else print “Error in status code” end_if end

Algorithm in Real Life Consider the following ….
Problem: Baking a Cake How to solve: Start Preheat the oven at 180oC Prepare a baking pan Beat butter with sugar Mix them with flour, eggs and essence vanilla Pour the dough into the baking pan Put the pan into the oven End

Problem: Prepare a Breakfast
Problem: Prepare a Breakfast 1. Start 2. Prepare a Breakfast 3. End

1. Start 2. Prepare a Breakfast 2.1. Prepare a tuna sandwich 2.1.1 Take 2 slices of bread 2.1.2 Prepare tuna paste 2.2. Prepare some chips 2.2.1 Cut potatoes into slices 2.2.2 Fry the potatoes 2.3. Make a cup of coffee 2.3.1 Boil water 2.3.2 Add water with sugar and coffee 3. End

Flow Chart Flowchart is another technique used in designing and representing algorithms. It is an alternative to pseudocode; whereas a pseudocode description is verbal while a flowchart is graphical in nature. a graph consisting of geometrical shapes that are connected by flow lines

Sub-module / Function (Barred Rectangle) Flow Direction Input/Output Connector Process Decision Start/Stop Representation Symbol

This symbol shows where a program begins and ends (program or module).
To identify the beginning and end of a whole program. The beginning terminal is labeled with start and the ending terminal is labeled with end or stop. When the flowchart is for a module, the beginning terminal is labeled with the module name and the ending terminal is labeled with return or exit.

totalSales = subTotal + pstAmount + gstAmount Area = Length * Width
Used to show tasks such as calculations, assignment statements, incrementing, etc. Processes are labeled with the statement the task to be performed, for example: totalSales = subTotal + pstAmount + gstAmount Area = Length * Width firstName = "Sally" Area = Length * Width

Examples get stdNumber
Used to show an operation that brings data into a program, or an operation that sends data out of the program. For example, getting values from the user or printing something on the screen. Input/output symbols are labeled with the statement that receives the input or generates the output, which could also include opening files and devices. Examples get stdNumber get stdNumber

numRecords > 10 foundMatch = true
Used to identify a point in the program where a condition is evaluated. Conditions are used in if statements and looping. Decisions are labeled with the condition that they are testing, for example: numRecords > 10 foundMatch = true numRecords > 10

-------------------------------------------------------------------
Sequence structure statement_1 statement_2 statement_n … Selection structure Yes condition then-part else-part No Yes condition then-part No

Repetition structure condition loop-body Yes No

Used to connect two segments of flowchart that appear on the same page.
This is done when your flowchart runs to the bottom of the page and we are out of room: end it with an on-page connector and then place another on-page connector in a free spot on the page, and continue the flowchart from that connector. On-page connectors are labeled with upper-case letters. The connector at the end of a segment of flowchart will match the connector that identifies the rest of the flowchart. For example, when we run out of room, end the flowchart with a connector labeled "A". The flowchart continues at the matching connector also labeled "A".

Used to specify a function/module call or a group of related statements.
Example Start Submodule End Return

The benefits of flowcharts
Communication Flowcharts are better way of communicating the logic of a system to all concerned. Effective analysis With the help of flowchart, problem can be analyzed in more effective way. Proper documentation Program flowcharts serve as a good program documentation, which is needed for various purposes. Efficient Coding The flowcharts act as a guide or blueprint during the systems analysis and program development phase. Proper Debugging The flowchart helps in debugging process. Efficient Program Maintenance The maintenance of operating program becomes easy with the help of flowchart. It helps the programmer to put efforts more efficiently on that part

Something to ponder … What are the problem solving process?

Problem Solving Process
Input Process Output

Example 1 Process Input Output
Calculate and display the price of a number of apples if the quantity in kg and price per kg are given. Input Process Output Quantity Price_per_kg Price = Quantity * Price_per_kg Price

Flowchart: Calculate Price of Apples
Start Input Quantity Input Price_per_kg Price = Quantity * Price_per_kg Output Price End

Programming Errors Another challenge that awaits is program debugging.
Debugging is defined as the process of finding and correcting errors in computer programs. No matter how careful you are as a programmer, most programs you write will contain errors. Either they won’t compile or they won’t execute properly. This situation is something that happens very frequently to every programmer. You should take program debugging as a challenge, develop your debugging skills, and enjoy the process. There are three types of programming errors: Syntax errors Logic errors Run-time errors

Syntax error: Logic error: Run-time error:
is violation of syntax rule, which define how the elements of a programming language must be written. They occur during the implementation phase and are detected by the compiler during the compilation process. Another name for syntax error is compilation error. Logic error: occur during the analysis, design, and implementation phases. We may choose an incorrect method of solution for the problem to be solved, mistakes in translating an algorithm into a program or design erroneous data for the program. Run-time error: are detected by the computer while the program is being executed. they are caused by program instructions that require the computer to do something illegal, such as attempting to store inappropriate data or divide a number by zero.

Debug To fix the program error, programmer will do debugging task by using debugger Debugging process can be very frustrating especially involving huge amount of coding Good to have good programming style and documentation in coding!

Debugger is a computer program that is used to test and debug other programs. Usually comes together with compilers Debugger will help programmer by provide list of error in compiling the program Still depends on programmers to solve the problem!!

Debugging technique Probe Trace
Put an external variable inside the program and try to force the program to output result in the middle. Good to trace modular logic error or data error Trace Back-tracking or front-tracking Go step-by-step (or line-by-line) to detect error. Good in tracking logic error and

Testing and Verification
In this phase, the main objective is to convince yourself and eventually your clients that the program will do what it is expected to do. In other words, you will want to verify that your program is correct. Program verification is the process of ensuring that a program meets user requirements. One of the techniques that can be used for program verification is program testing. Program testing is the process of executing a program to demonstrate its correctness. A program must be tested using a sufficiently large sample of carefully designed test data sets such that every logical path in the program is traversed at least once. You must continue to test your program until you are sure that all statements in it are functioning correctly.

Documentation Program documentation consists of these elements:
A concise requirements specification Descriptions of problem inputs, expected outputs, constraints, and applicable formula A pseudocode and flowchart for its algorithm A source program listing A hardcopy of a sample test run of the program A user’s guide explaining to non-programmer users how the program should be used. Documentation can and should be done within the coding itself by using comments!!

End of Lecture 2 Yes !! That’s all? What’s next??? Test your skills…

Example of Problem Solving
1.Design the algorithm for making a pot of tea write pseudo-code and the flow chart.

Answer: Pseudocode: Start Fill a kettle with water Boil the water in the kettle Put the tea leaves in the pot Pour boiling water in the pot End

Flowchart Start Fill a kettle with water Boil the water in the kettle
Put the tea leaves in the pot Pour boiling water in the pot End

2. Design the algorithm (pseudo-code) and the flow chart for calculating the perimeter of a circle

Answer: Pseudocode: Start Input Radius Calculate perimeter = 44/7 * Radius Print Perimeter End

Flowchart Start Input Radius Perimeter = 44/7 * Radius Print Perimeter
End

3. Design the algorithm (use pseudo-code &
flowchart) for summing of 2 numbers.

Answer: Start Input X Input Y Calculate Sum=x+y Print Sum End
Pseudocode: Start Input X Input Y Calculate Sum=x+y Print Sum End

Flowchart Start Input X Input Y Sum = X+Y Print Sum End

TMC 1414 Introduction to Programming

Similar presentations

Presentation on theme: "TMC 1414 Introduction to Programming"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

TMC 1414 Introduction to Programming

Similar presentations

Presentation on theme: "TMC 1414 Introduction to Programming"— Presentation transcript:

Similar presentations

About project

Feedback