Programming in C - Problem Solving using C
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- 5. • Problem solving is the systematic approach to define the problem and creating number of solutions. • The problem-solving process starts with the problem specifications and ends with a Correct program. • Problem solving technique is a set of techniques that helps in providing logic for solving a problem. • The problem-solving Techniques can be expressed in the form of Algorithms, Flowcharts, Pseudo code and Programs PROBLEMSOLVING 5
- 6. STEPS IN PROBLEM SOLVING 6 • Problem definition • Problem analysis • Algorithm Development • Program coding • Program testing and Debugging • Documentation
- 7. Problem Definition - understand the problem Define or specify the problem by answering the following questions: • What the computer program do? • What tasks will it perform? • What kind of data will it use and where will it get the data? • What will be the output of the program? • How will the program interact with the computer user? Problem Analysis – determine the requirements Analysing the problem involves • Identifying the problem inputs • Check any additional requirements or constraints • Determine the required format of the results to be displayed 7
- 8. Algorithm Development - develop a step by step procedure to solve the problem • Find an algorithm for its solution • An algorithm is a finite set of steps defining the solution of a particular problem • The algorithm development can be expressed by Pseudo code and Flowchart Program Coding - uses a programming language to write or implement the actual programming instructions Coding or programming is the process of translating the algorithm into the syntax of a given programming language. • Convert each step in the algorithm into one or more statements in a programming language 8
- 9. Program Testing and Debugging • Program testing means running the program and executing all its instructions or functions step by step. • Debugging is the process of finding and correcting program code mistakes. • Errors in the program may be Syntax errors, Run time errors and Logic Errors(bugs) Documentation • Internal Documentation: It consists of remarks or comments written with the program instructions to explain what is being done in the program • External Documentation: It is made up of the manuals or help menus written about the solution 9
- 10. Three ways of Representation • Algorithm • Pseudo-code • Flowchart Algorithm • Set of step-by-step instructions that perform a specific task or operation REPRESENTATION OF PROBLEM SOLVING SOLUTION 10
- 11. Pseudo-code • Set of instructions that mimic programming language instructions REPRESENTATION OF SOLUTION 11
- 12. D I F F E R E N C E B E T W E E N A L G O R I T H M A N D P S E U D O C O D E • An algorithm is a precise and well-defined procedure • Pseudocode is a more informal and high-level representation of an algorithm. 12 Representation of Solution
- 13. Flowchart • Schematic representation of an algorithm REPRESENTATION OF SOLUTION 13
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- 15. • How to cut a circular cake into 8 equal pieces only with 3 cuts 15
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- 18. • An algorithm is a detailed step by step instructions for solving a problem in a finite amount of time • Used in solving mathematical or sometimes computational problems 11 Algorithm
- 19. 11 Algorithm Steps involved in algorithm development An algorithm can be defined as “a complete, unambiguous, finite number of logical steps for solving a specific problem “ . Step1. Identification of input: For an algorithm, there are quantities to be supplied called input and these are fed externally. The input is to be indentified first for any specified problem. Step2: Identification of output: From an algorithm, at least one quantity is produced, called for any specified problem. Step3 : Identification the processing operations : All the calculations to be performed in order to lead to output from the input are to be identified in an orderly manner.
- 20. 11 Algorithm Steps involved in algorithm development Step 4: Processing Definiteness: The instruction composing the algorithm must be clear and there should not be any ambiguity in them. Step5 : Processing Finiteness : If we go through the algorithm, then for all cases, the algorithm should terminate after a finite number of steps. Step6 : Possessing Effectiveness : The instructions in the algorithm must be sufficiently basic and in practice they can be carries out easily
- 21. Introduction to Algorithm • Input • Output • Finiteness • Definiteness/Concise • Effectiveness Characteristics of Algorithm 12
- 22. Input • Algorithm should have well-defined inputs Output • Algorithm should have well-defined outputs, and should match the desired output Finiteness • Algorithms must terminate after a finite number of steps Definiteness/Concise • Each step must be precisely defined • Actions to carryout must be unambiguously (not confusing) specified Effectiveness • All operations must achieve the goal 13 Characteristics of Algorithm
- 23. 23 A Jeroo starts at (0, 0) facing East with no flowers in its pouch. There is a flower at location (3, 0). Write an algorithm that directs the Jeroo to pick the flower and plant it at location (3, 2). After planting the flower, the Jeroo should hop one space East and stop. There are no other nets, flowers, or Jeroos on the island. WRITE ALGORITHM – SIMPLE EXAMPLE
- 24. 1.The flower is exactly three spaces ahead of the jeroo. 2.The flower is to be planted exactly two spaces South of its current location. 3.The Jeroo is to finish facing East one space East of the planted flower. 4.There are no nets to worry about. Get the flower Put the flower Hop East Get the flower Hop 3 times Pick the flower Put the flower Turn right Hop 2 times Plant a flower Hop East Turn left Hop once Analysis of the Problem High-level Algorithm Detailed Algorithm WRITE ALGORITHM
- 25. Example for Algorithm Problem - Write an Algorithm to Multiply two numbers Step 1 - Start Step 2 - Declare three Integers a, b, c Step 3 - Define Values of a, b Step 4 - Multiplication of a, b Step 5 - Store the Output of step 4 to c Step 6 - Print the value c Step 7 - Stop Example for Algorithm: 14
- 26. Applications of Algorithm • Google Search • Uber App • Video Games • NASA’s Manipulation of Space Ships • FaceBook Timeline Applications of Algorithm: 15
- 27. Advantages & Disadvantages of Algorithm Advantages • It makes the representation of a solution to a problem easy, which makes easier in understanding • It can be easily understood by a person without even having the knowledge of programming • It follows a definite procedure Disadvantages • It takes very long in writing an algorithm • It is not a computer program, neither it helps in reducing the difficulties while writing a code 16
- 28. L E T S H A V E A B R E A K • A doctor’s son’s father was not a doctor. How is this possible? • A man was born in 1945, but he’s only 30 years old now. How is this possible? 28
- 29. L E T S H A V E A B R E A K • A doctor’s son’s father was not a doctor. How is this possible? • The doctor is the mother. • A man was born in 1945, but he’s only 30 years old now. How is this possible? • 1945 was the number of the hospital room. 29
- 30. Summary • Overview of Computer Programming • Problem Solving • Steps in Problem Solving • Representation of Problem Solving Solution • Algorithm • Characteristics of Algorithm • Example for Algorithm • Applications of Algorithm • Advantages & Disadvantages of Algorithm Introduction to Problem Solving, Algorithm Implementation 17
- 31. PEER LEARNING 1. Write an algorithm to calculate your cut-off? 2. Steps to admit in an engineering college through counseling 3. Write an algorithm to build a Calculator 4. Addition of three numbers entered by the user 5. Find the largest number among three different numbers 6. Check whether a number is a prime number or not 7. Factorial of a number entered by the user 19 Introduction to Problem Solving, Introduction to Algorithm
- 32. Try Yourself 1. Mary Williams needs to change a Fahrenheit temperature to Celsius. Use the Fahrenheit temperature of 80 degrees to test your solution. Celsius = ((Fahrenheit - 32) * 5/9) 2. Calculate the area for a circle and display the result with proper output message. (Hint = ^2) 𝐴𝑟𝑒𝑎 𝜋𝑟 19 ntroduction to Problem Solving, Introduction to Idea of Algorithm
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- 34. TOP DOWN DESIGN 34 • A method of breaking a problem down into smaller, less complex pieces from the initial overall problem. • Most “good” problems are too complex to solve in just one step, so we divide the problem up into smaller manageable pieces, solve each one of them and then bring everything back together again. • The process of making the steps more and more specific in top-down design is called stepwise refinement. • Top-Down Design (Divide-and-Conquer) • Write functions top-down • Test functions bottom-up • Practicality: May help to write stubs (simulated functions as temporary placeholders in top-down design)
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- 36. • A parent node is one that has other nodes descending from it - we say that a node is the parent of some other node. • In the same way a child node is one that descends from a parent node. • The root node can only be a parent node. • Leaf nodes can only be child nodes. • Intermediate nodes can be both parent or child nodes depending on the desired perspective. • All nodes in the tree are children of the root node. Conversely the root node is a parent of all other nodes in the tree. • Sibling nodes are two or more nodes at the same level which are descended from the same parent. • The depth (or height) of a tree refers to the number of levels in the tree. • The width of a tree refers to the maximum number of nodes at any one level. 36
- 37. T O P - D O W N D E S I G N • A software development technique that imposes a hierarchical structure on the design of the program. • It starts out by defining the solution at the highest level of functionality and breaking it down further and further into small routines that can be easily documented and coded. • Also known as: • Divide and conquer • Stepwise refinement • Structured programming 37
- 38. A D V A N T A G E S O F T O P - D O W N D E S I G N • Breaking the problem into parts helps to clarify what needs to be done. • At each step of refinement, the new parts become less complicated and, therefore, easier to figure out. • Breaking the problem into parts allows more than one person to work on the solution. 38
- 39. SIMPLE STRATEGIES FOR DEVELOPING ALGORITHMS 39 • Developing an algorithm is a very important step in problem-solving. There are different types of strategies that could be used to develop an algorithm to solve a problem. • Two of the most frequently used strategies are: – Iteration – Recursion
- 40. 1. Iterations: A sequence of statements is executed until a specified condition is true is called iterations. 1. 2. for loop While loop For loop : FOR( start-value to end-value) DO Statement ... ENDFOR 40
- 41. Example: Print n natural numbers BEGIN GET n INITIALIZE i=1 FOR (i<=n) DO PRINT i i=i+1 ENDFOR END 41
- 42. Syntax for While: WHILE (condition) DO Statement ... ENDWHILE Print n natural numbers BEGIN GET n INITIALIZE i=1 WHILE(i<=n) DO PRINT i i=i+1 ENDWHILE END 42
- 43. • Recursion is a technique in which a function calls itself repeatedly until a concluding situation happen. • A function which utilizes this technique is called a recursive function • Using recursive algorithm, certain problems can be solved quite easily. • Examples of such problems are • Towers of Hanoi (TOH) • In order/Preorder/Post order Tree Traversals, • DFS of Graph, etc. RECURSION 43