Algorithm

What is Algorithmic Thinking?

  • Algorithmic Thinking is the process of solving problems using step-by-step instructions.

  • It involves logical decisions like:

    • Adding numbers

    • Checking conditions

    • Repeating steps (loops)

What is an Algorithm?

  • Definition: A sequence of clearly defined and ordered steps to solve a problem.

  • Two main principles:

    1. Definiteness – Steps must be clear and unambiguous.

    2. Sequential Order – Steps must follow a specific order with a clear start and end.

State of an Algorithm

  • The state refers to what’s happening at a certain step in the process.

  • Example: 

    a = 4
a = 40
a = 400
b = a
c = a / 40

    • The state changes at each step, affecting variables (a, b, c).

Algorithms vs. Programs

  • Algorithm: General step-by-step procedure for solving a problem.

  • Program: A set of instructions written in a programming language for a computer to execute.

How to Write an Algorithm?

  • Can be written in:

    • Natural language (simple sentences)

    • Programming languages (Python, Java, etc.)

    • Flowcharts (graphical representation)

Importance of Sequence in Algorithms

  • Order of execution matters!

  • Example: 

    6 / 2 * (2 + 1)

    • Left Calculator: 6 / [2 * 3] = 6 / 6 = 1

    • Right Calculator: [6 / 2] * 3 = 3 * 3 = 9

    • Different results due to order of operations!

How to Structure an Algorithm?

  1. Input → What information do we start with?

  2. Process → What steps transform the input into the solution?

  3. Output → What is the final result?

Flowcharts & Algorithm Representation

  • Flowchart Symbols:

    • Oval: Start/End

    • Parallelogram: Input/Output

    • Rectangle: Process

    • Diamond: Decision

  • Example: Flowchart for calculating a final grade.

Programming & Algorithmic Thinking

  • Logic Formulation:

    • You can find multiple ways to solve a problem.

    • Creativity matters!

  • Syntax:

    • You must follow rules of a programming language to express logic correctly.

    • Example in Python: 

      name = input("What’s your name? ")
age = input("What’s your age? ")
print("Hello", name, "! Nice to meet you.")

Python Programming & Algorithmic Thinking

  • Python is a high-level programming language with:

    • Readable syntax

    • Simple structure

    • Dynamic execution

  • Example: 

    students = int(input("Enter number of students: "))
sections = int(input("Enter number of sections: "))
students_per_section = students / sections
print("Each section has", students_per_section, "students.")

Why is Programming Useful?

  • Computers follow instructions exactly.

  • Humans can adapt to errors, but computers cannot.

  • Understanding programming helps develop problem-solving skills.

Key Takeaways

  • Algorithmic thinking is essential for problem-solving.

  • An algorithm is a structured, step-by-step procedure.

  • Programs execute algorithms using programming languages.

  • Python makes it easier to write algorithms.