Data Structure & Algorithm

Data Structure & Algorithm

 $\sim$  B.Eng (HONS) Jafran Jemal 
  (CEO & FOUNDER of JJSOFT)

Programming

• Problem solving phase

• Implementation phase

Problem solving phase

produce an ordered sequence of steps that describe solution of problem

this sequence of steps is called an algorithm

STEPS IN PROBLEM SOLVING

• First produce a general algorithm (one can use pseudo code)

• Refine the algorithm successively to get step by step detailed algorithm that is very close to a computer language

Pseudo code

Pseudo code is an artificial and informal language that helps programmers develop algorithms. Pseudo code is very similar to everyday English.

Example 1

Write an algorithm to determine a student’s final grade and indicate whether it is passing or failing. The final grade is calculated as the average of four marks.

Pseudo code

 Input a set of 4 marks

 Calculate their average by summing and dividing by 4

 if average is below 50 Print “FAIL” else Print “PASS”

Detailed Algorithm

Step 1: Input M1,M2,M3,M4

Step 2: GRADE (M1+M2+M3+M4)/4

Step 3: if (GRADE < 50) then Print “FAIL” else Print “PASS” endif

THE FLOWCHART

 (Dictionary) A schematic representation of a sequence of operations, as in a manufacturing process or computer program.

 (Technical) A graphical representation of the sequence of operations in an information system or program. Information system flowcharts show how data flows from source documents through the computer to final distribution to users. Program flowcharts show the sequence of instructions in a single program or subroutine. Different symbols are used to draw each type of flowchart.

A Flowchart

• shows logic of an algorithm

• emphasizes individual steps and their interconnections

• e.g. control flow from one action to the next

Exercise 1

Write an algorithm and draw a flowchart that will read the two sides of a rectangle and calculate its area.

Pseudocode

Input the width (W) and Length (L) of a rectangle Calculate the area (A) by multiplying L with W

Print A

Algorithm

• Step 1: Input W,L

• Step 2: A L x W

• Step 3: Print A

DECISION STRUCTURES ( IF-THEN-ELSE )

• The expression A>B is a logical expression

• it describes a condition we want to test

• if A>B is true (if A is greater than B) we take the action on left

• print the value of A 

Implementation phase

implement the program in some programming language

Implementation (Live Coding)

Bonouse -> Convert Algorithm to ≻ Working Program/App

Open Ended

Today what do you learned ?

Thank You