Computational Thinking IT Unit-3 Notes PDF

# COMPUTATIONAL THINKING AND I.T ## Unit-3 ALGORITHMIC THINKING ### ALGORITHMS An Algorithm is a defined set of step-by-step procedures that provides the correct answer to a particular problem. An Algorithm (pronounced AL-go-rith-um) is a procedure or formula for solving a problem. It can be formall...

# COMPUTATIONAL THINKING AND I.T ## Unit-3 ALGORITHMIC THINKING ### ALGORITHMS An Algorithm is a defined set of step-by-step procedures that provides the correct answer to a particular problem. An Algorithm (pronounced AL-go-rith-um) is a procedure or formula for solving a problem. It can be formally written down and has very practical consequences to achieve software re-use which helps in saving a lot of time for software developers. ### DEFINATION OF ALGORITHM In Computer Science, an algorithm usually means a small procedure that solves a recurrent problem. It abstracts the data, operations and semantics of a problem and then creates a solution using all those abstractions. It describes the process of solving a particular problem. Algorithm play a very important role in designing good software and also help in finding the best solution to a problem. Below is given a list of advantages and disadvantages. ### ADVANTAGES OF ALGORITHM - Logic can be developed independent of a programming Language. - Can be easily transformed to a program in any computer language. - Step-by-step approach assists in finding and correcting errors in programs. - Can be easily understood by a Programmer. - Leads to problem solution in a finite amount of time. ### DISADVANTAGES OF ALGORITHM - Difficult tasks are difficult to be explained using Algorithm. - Time-consuming to develop and prove their accuracy. - It is difficult to show some programming constructs like looping and branching. ### CHARACTERISTICS OF AN ALGORITHM - **INPUT:** It should have the ability to accept zero or more well-defined inputs. - **DEFINITENESS OR UNAMBIGUOUS:** Each step or operation must be well-defined. It means that each instruction must be specified unambiguously. - **EFFECTIVENESS OR FEASIBLE:** Each step should be feasible to be carried out by a person using pencil and paper in a finite amount of time. - **TERMINATE / FINITENESS:** The problems solving process after some steps must lead to a solution of the problem. - **OUTPUT:** It must produce one or more Output as an outcome of following the steps in an algorithm. ### EXAMPLES OF ALGORITHM (Sequencing, Selection, Iteration) #### a) Sequencing - A sequencing algorithm is a set of instructions that are performed in a specific order to complete a task. In a sequencing algorithm, the order of the instructions is important. - If the instructions are not followed in the correct order, the task will be incompleted or ambiguous. **1. Write an algorithm to find the sum of two Numbers.** - **STEP 1:** START - **STEP 2:** [Read two number into a, b] INPUT a, b - **STEP 3:** [Complete the Sum] Sum = a+b - **STEP 4:** [Display the Result] OUTPUT SUM - **STEP 5:** [End of the Algorithm] Exit **2. Write an algorithm to find Area of Circle:** - **STEP 1:** START - **STEP 2:** [Define the value of PI] PI = 3.142 - **STEP 3:** [Read the value of Radius] INPUT - **STEP 4:** [Compute Area] area = PI*γγ - **STEP 5:** [Print the Compound Area] Output area - **STEP 6:** [End of the Algorithm] EXIT **3. Write an algorithm to find Area of Triangle (Heron's formula)** - **STEP 1:** START - **STEP 2:** [Read values length of sides of a triangle] INPUT a, b, c - **STEP 3:** [Compute semi-perimeter,s] S= (a+b+c)/2 - **STEP 4:** [Compute the area] area=SQRT(S*(s-a)*(s-b)*(s-c)) - **STEP 5:** [Print the Computed Area] Output Area. - **STEP 6:** [End of the Algorithm] Exit #### b) Selection - It is an Algorithm to find the smallest value in a set of ordered values. - Selection algorithm can also be used to evaluate components of random solution of Set for a problem. It can also find the median or maximum value in a set. **Write an algorithm to find the largest of three numbers.** - **STEP 1:** START. - **STEP 2:** [Read valve of 3 Numbers] INPUT a, b, c - **STEP 3:** [Assume / 1Assign a to large] large = a - **STEP 4:** [Compare large with b] if (b> large) large = b endif - **STEP 5:** [Compare large with C] if (c> large) large = C end if - **STEP 6:** [Print the largest value] OUTPUT large. - **STEP 7:** [End of the Algorithm] Exit #### c) Iteration - Iteration algorithm means repeating steps, or instruction close instruction. A single Action that can be performed by a computer processor. over and over again. It can solve the complex problems. **1. Write an algorithm to find the factorial of a Number.** - **STEP 1:** START - **STEP 2:** (Read a Number] INPUT n - **STEP 3:** CInitialize Factorial to 1] Jact = 1. - **STEP 4:** [Compute factorial by Progressive multiplication] Repeat For i = 1 ton fact = fact*i [End of STEP 4 for Loop] - **STEP 5:** [Print factorial] OUTPUT facts - **STEP 6:** (End of the Algorithm] Exit **2. Write an Algorithm to find GCD of two Numbers Using Euclid's Algorithm.** - **STEP 1:** START. - **STEP 2:** [Read two numbers] INPUT a, b - **STEP 3:** CGCD Calculation) Repeat while (b!=0) r = a MOD b a = b b = r [End of while Loop] - **STEP 4:** [Print the GCD i-e, last Divisor] Print a - **STEP 5:** [End of the Algorithm] Exit