Agorithms explanation

1. Subject
Design and Analysis of Algorithms
BS(CS) 4th

2. Lecture#01
Introduction to Design and Analysis of
Algorithms

3. What Is an Algorithm?
 “An algorithm is a well-defined procedure that allows a computer
to solve a problem.”
A sequence of unambiguous instructions.
The use of the term 'unambiguous' indicates that there is no room
for subjective interpretation.
 Every time you ask your computer to carry out the same
algorithm, it will do it in exactly the same manner with the exact
same result.
. For example, you start working on a report.

4. How Do Algorithms Work?
A very simple example of an algorithm would be to find
the largest number in an unsorted list of numbers L.
 If you were given a list of five different numbers.
L1 is first element and L2 second and so on.

5. The algorithm would look something like this:
Step 1: Let Largest = L1
This means you start by assuming that the first number is the largest
number.
Step 2: For each item in the list:
This means you will go through the list of numbers one by one.
Step 3: If the item > Largest:
If you find a new largest number, move to step four. If not, go back to
step two, which means you move on to the next number in the list.
Step 4: Then Largest = the item
This replaces the old largest number with the new largest number you
just found. Once this is completed, return to step two until there are no
more numbers left in the list.
Step 5: Return Largest

6.  Algorithm is described as a series of logical steps in a language
that is easily understood.
 For a computer to actually use these instructions, they need to be
written in a language that a computer can understand, known as
a programming language
Notice

7. What is the use of algorithm in computer system?
An algorithm is a sequence of instructions for a computer system
like a recipe for cooking
Tells the computer what to do and how to do it
Algorithms are expressed in a programming language like C++or
Assembler

8. Why We use Algorithm ?
Algorithm helps to solve computational problems.
Solid Algorithmic knowledge & technique separates the
truly skilled programmer from the novices
Algorithmic analysis will clear your vision about a
computational problem & will let you go farther with it
Algorithms are the core of most technologies that we see
in modern electronic devices
And many more...

9. What is Algorithm Design?
 Since computer-processed algorithms can tackle much larger
problems than a human, much more quickly.
Since modern computing uses algorithms much more frequently
than at any other point in human history.
Field has grown up around their design, analysis, and refinement.
The field of algorithm design requires a strong mathematical .
Designing algorithm is necessary before writing the program code .
Explains the logic even before the code is developed.

10. What is Algorithm Analysis?
The process of analyzing the problem-solving capability of the
algorithm in terms of the time and size required.
How to choose a better algorithm for a particular problem as one
computational problem can be solved by different algorithms.
Algorithms are often quite different from one another, though the
objective of these algorithms are the same.
Time Complexity
Space Complexity
Bubble sort
Merge Sort

11. Why Algorithms Analysis is Needed?
Why is design and analysis of algorithm important to study?
Problem Development Steps
Characteristics of Algorithms
Pseudocode
Difference between Algorithm and Pseudocode