Building Blocks of Algorithm in Python

Sequence, selection, and iteration are the fundamental building elements from which algorithms may be built.

Statements:

In a computer, a statement is one action.

Statements in a computer might contain some of the following operations:

• Input data information sent to the software.
• Process data and execute an operation on an input.
• Output the processed data result.

State

State is the transition, during a certain time interval, from one process to another under specified conditions.

Control Flow:

Control flow is the process of carrying out each statement in a predetermined order.

There are three approaches to implementing the control:

• Sequence
• Selection
• Iteration

Sequence:

Sequence execution is the process of carrying out each instruction one after the other. This building block entails specifying a set of actions that must be carried out in a particular order. Usually, sequences are employed for simple, linear operations. For instance, you would construct a series that adds two integers to find their sum.

For Example:

Add two numbers:

Step 1: Start

Step 2: Get a, b

Step 3: Calculate c = a + b

Step 4: Display c

Step 5: Stop

Selection:

A selection statement transfers program control, condition-based, to a particular section of the program.

One portion of the program will run if the conditional test is true; if not, the other portion of the program will run.

An algorithm may decide depending on conditions, thanks to selection. The 'if' statement is the most used selection construct. It allows you to run distinct code blocks based on the truth value of a given condition. For example, you can use 'if' to check if a given integer is odd or even.

For Example:

Write an algorithm to check whether he is eligible to vote.

Step 1: Start

Step 2: Get age

Step 3: If age >= 18, print "Eligible to vote"

Step 4: Else print "Not eligible to vote"

Step 5: Stop

Iteration:

Certain statements are repeatedly run in some programs depending on conditional tests. i.e., carried out repeatedly. We refer to this kind of operation as looping or iteration. Iteration is the process of repeating a set of instructions several times, frequently with the use of Python loops like "for" and "while." Loops are essential for processing data structures or performing repeating operations. For instance, you may execute the same action on each item in a list by iterating across the list.

For Example:

Write an algorithm to print all natural numbers up to n

Step 1: Start

Step 2: Get n value.

Step 3: Initialize i = 1

Step 4: If (i <= n), go to step 5 else go to step 7

Step 5: Print i value and increment i value by 1

Step 6: Go to step 4

Step 7: Stop

Functions:

• A function is a subprogram that carries out a certain job and is made up of a block of code (a series of instructions).
• During the algorithm design process, complicated challenges are broken down into smaller, easier ones.

Advantages of Function Use

• Shortening of the code line
• Reusing code
• Improved legibility
• Information concealment
• Simple to test and troubleshoot
• Enhanced sustainability

For Example:

Algorithm for addition of two numbers using function

Main function ()

Step 1: Start

Step 2: Call the function add ()

Step 3: Stop

sub-function add ()

Step 1: Function start

Step 2: Get a and b values

Step 3: add c = a + b

Step 4: Print c

Step 5: Return