problem solving skills and its related all information
- 2. Problem A well-defined problem has five components: • A clearly defined initial situation given • A clearly defined goal • A clearly defined set of resources • A clearly defined constraints • Ownership
- 3. Case Study You are at a river that you want to cross with all your goods. Your goods consist of a chicken, a bag of grain and your cat. You have to cross the river in your boat but can only take one passenger with you at a time – the chicken, the cat or the bag of grain. You can’t leave the chicken alone with the grain as the chicken will eat the grain. You can’t leave your cat alone with the chicken as cat will eat the chicken. However, you know that cat does not eat grain. How do you get everything across the river intact?
- 4. Problem • Initial Situation: You, the Chicken, the Bag of Grain and the Cat are on one bank of a river with access to a boat. • Resources: The boat and your knowledge and problem-solving skills. • Constraints: You can take only one passenger, you must not leave Cat with the Chicken, you must not leave the Chicken with the Grain. • Goal: You, the Chicken, the Bag of Grain and the Cat on the opposite bank of river. • Ownership: You will be involved in planning the solution and carrying it out
- 5. Solution • Take the chicken across the river and leave it on the other side. Return to where you have left Cat and the Grain. • Take Cat across the river and leave him on the other side. Take back the chicken. • Leave the chicken where you started. Take the bag of grain across the river and leave it with the Rover. • Go back and fetch the chicken and take it across the river with you.
- 6. Problem Solving • Problem solving is a process of identifying a problem and finding the best solution for it. • Problem solving is a skill that can be developed by following a well organized approach. • Different strategies, techniques and tools are used to solve a problem.
- 7. Problem Solving (Cont.) When faced with a problem: 1. We first clearly define the problem 2. Think of possible solutions 3. Select the one that we think is the best under the prevailing circumstances 4. And then apply that solution 5. If the solution woks as desired, fine; else we go back to step 2
- 8. Problem Solving (Cont.) • Computers are used as a tool to solve a complex problems by developing computer programs. • Computer programs contain different instructions for computer. • A programmer writes instructions and computer executes these instructions to solve a problem. • Different problem solving techniques are as follows: Algorithm Flowchart Program
- 9. Algorithm • From programming point of view, an algorithm is a step-by-step procedure to resolve any problem. • An algorithm is an effective method expressed as a finite set of well-defined instructions.
- 10. Three Requirements 1. Sequence is: Precise Consists of limited number of steps 2. Each step is: Unambiguous Executable 3. The sequence of steps terminates in the form of a solution
- 11. Properties of Algorithm • Following are some properties of an algorithm: The given problem should be broken down into simple and meaningful steps. The steps should be numbered sequentially The steps should be descriptive and written in simple English.
- 12. Sample Algorithm Write an algorithm to find area of a rectangle Step 1: Start Step 2: get l,b values Step 3: Calculate A=l*b Step 4: Display A Step 5: Stop
- 13. Sample Algorithm - 2 Write an algorithm to add two numbers 1. Start 2. Read the value of num1 3. Read the value of num2 4. Add num1 and num2 5. Store the result in a variable sum 6. Display sum 7. End
- 14. Analysis of Algorithm • Analysis in the context of algorithms is concerned with predicting the resources that are required: Computational Time Memory Bandwidth Logic functions • However, Time – generally measured in terms of number of steps required to execute an algorithm is the resource of most interest • By analyzing several algorithms, the most efficient one can be identified
- 15. Algorithm Techniques Different kind of algorithm strategies are there which people follow to write an algorithm: • Greedy Algorithm • Deterministic Algorithm • Randomized Algorithm • Brute Force Strategy
- 16. Traveling Salesman Problem • A salesman needs to visit each of the n cities. • Is there is a route that takes the salesman through every city and back to starting city A at a cost of $520?
- 17. Few Questions • Is that the best possible sequence? • How do you know? • How do I determine the best sequence? (How do I determine the sequence that I draw is the best one, shortened one and optimist one.) Solution: you have to list down all possible combinations, compute all possible distances. Have to find minimum distance
- 18. SYNTAX & SEMANTICS • An algo. is correct if its: Syntax is correct Semantics are correct • Semantics: The concept embedded in an algorithm(the soul!) • Syntax: The actual representation of an algorithm(the body!)
- 19. Pseudo code • Algorithms are written in a language that is similar to simple English called pseudo code. • There is no standard to write pseudo code. • It is used to specify program logic in an English like manner that is independent of any particular programming language.
- 20. Pseudo Code (Cont.) • Pseudo code simplifies program development by separating it into two main parts: Logic Design Coding • Logic Design: In this part, the logic of the program is designed. We specify different steps required to solve the problem and the sequence of these steps. • Coding: In this part, the algorithm is converted into a program. The steps of algorithm are translated into instructions of any programing language.
- 21. Sample Pseudocode Write pseudocode to find area of a rectangle BEGIN READ l,b CALCULATE A=l*b DISPLAY A END
- 22. Sample Pseudocode Write pseudocode to add two numbers BEGIN NUMBER num1, num2, sum OUTPUT ("Input number1:") INPUT num1 OUTPUT ("Input number2:") INPUT num2 sum= num1 + num2 OUTPUT sum
- 23. Difference Between Algorithm and Pseudocode Parameters Algorithm Pseudocode Meaning and Definition An algorithm is a systematic, logical approach that provides a step-by-step procedure for computers to solve a specific problem. Pseudocode is a simplified version of programming codes, written in plain English language and used to outline a program before its implementation. Expression and Use Algorithms can be expressed using flowcharts, natural language, and other methods. Pseudocode includes various control structures such as repeat-until, if-then-else, while, for, and case.