2. ALGORITHMS, FLOWCHARTS, DATA
TYPES AND PSEUDOCODE
2.1 ALGORITHMS
The term algorithm originally referred to any computation performed via a set of rules
applied to numbers written in decimal form. The word is derived from the phonetic
pronunciation of the last name of Abu Ja'far Mohammed ibn Musa al-Khowarizmi, who
was an Arabic mathematician who invented a set of rules for performing the four basic
arithmetic operations (addition, subtraction, multiplication and division) on decimal
numbers.
An algorithm is a representation of a solution to a problem. If a problem can be defined
as a difference between a desired situation and the current situation in which one is, then
a problem solution is a procedure, or method, for transforming the current situation to the
desired one. We solve many such trivial problems every day without even thinking about
it, for example making breakfast, travelling to the workplace etc. But the solution to such
problems requires little intellectual effort and is relatively unimportant. However, the
solution of a more interesting problem of more importance usually involves stating the
problem in an understandable form and communicating the solution to others. In the case
where a computer is part of the means of solving the problem, a procedure, explicitly
stating the steps leading to the solution, must be transmitted to the computer. This
concept of problem solution and communication makes the study of algorithms important
to computer science.
Throughout history, man has thought of ever more elegant ways of reducing the amount
of labour needed to do things. A computer has immense potential for saving time/energy,
as most (computational) tasks that are repetitive or can be generalised can be done by a
computer. For a computer to perform a desired task, a method for carrying out some
sequence of events, resulting in accomplishing the task, must somehow be described to
the computer. The algorithm can be described on many levels because the algorithm is
just the procedure of steps to take and get the result. The language used to describe an
algorithm to other people will be quite different from that which is used by the computer,
however the actual algorithm will in essence be the same. An example of an algorithm
people use would be a recipe to make a cake.
"4 extra large eggs, beaten
1&1/2 C. stock
1/2 teaspoon salt
1 scallion, minced
1 C. small shrimp or lobster flakes
1 t. soy sauce
1 Tablespoon oil
1. Mix all the ingredients, except the oil, in a deep bowl.
MT 512: Programming Design Page no: 6
, 2. Put 1" water in wide pot, then place deep bowl of batter inside.
3. Cover pot tightly and steam 15 min.
4. Heat oil very hot and pour over custard.
5. Steam 5 more min. Serves 4 people"
This breaks down 'Making Chinese egg custard' into smaller steps. To make the product
one still needs to know how to execute each of the steps in the procedure and understand
all of the terms.
Definition:
A procedure is a finite sequence of well-defined instructions, each of which can be
mechanically carried out in a finite amount of time.
The procedure must break up the problem solution into parts that the recipient party can
understand and execute. In the case of a computer, the problem solution is usually in the
form of a program that encompasses the algorithm and explains to the computer a clearly
defined procedure for achieving the solution. The procedure must consist of smaller steps
each of which the computers understand. There may be no ambiguities in the translation
of the procedure into the necessary action to be taken. A program is then just a specific
realisation of an algorithm, which may be executed on a physical device.
A computer is essentially a physical device designed to carry out a collection of primitive
actions. A procedure is a sequence of instructions written in terms of which evoke a
proper operation. To make effective use of an algorithm on a computer one must not only
find and understand a solution to the problem but also convey the algorithm to the
computer, giving the correct sequence of understood commands that represent the same
algorithm.
Definition:
An algorithm is procedure consisting of a finite set of unambiguous rules (instructions)
which specify a finite sequence of operations that provides the solution to a problem, or
to a specific class of problems for any allowable set of input quantities (if there are
inputs). In other word, an algorithm is a step-by-step procedure to solve a given problem
Alternatively, we can define an algorithm as a set or list of instructions for carrying out
some process step by step. A recipe in a cookbook is an excellent example of an
algorithm. The recipe includes the requirements for the cooking or ingredients and the
method of cooking them until you end up with a nice cooked dish.
In the same way, algorithms executed by a computer can combine millions of elementary
steps, such as additions and subtractions, into a complicated mathematical calculation.
Also by means of algorithms, a computer can control a manufacturing process or co-
MT 512: Programming Design Page no: 7
, ordinate the reservations of an airline as they are received from the ticket offices all over
the country. Algorithms for such large-scale processes are, of course, very complex, but
they are built up from pieces.
One of the obstacles to overcome in using a computer to solve your problems is that of
translating the idea of the algorithm to computer code (program). People cannot normally
understand the actual machine code that the computer needs to run a program, so
programs are written in a programming language such as C or Pascal, which is then
converted into machine code for the computer to run.
In the problem-solving phase of computer programming, you will be designing
algorithms. This means that you will have to be conscious of the strategies you use to
solve problems in order to apply them to programming problems. These algorithms can
be designed though the use of flowcharts or pseudocode.
2.2 FLOWCHARTS
Flowcharting is a tool developed in the computer industry, for showing the steps
involved in a process. A flowchart is a diagram made up of boxes, diamonds and other
shapes, connected by arrows - each shape represents a step in the process, and the arrows
show the order in which they occur. Flowcharting combines symbols and flowlines, to
show figuratively the operation of an algorithm.
In computing, there are dozens of different symbols used in flowcharting (there are even
national and international flowcharting symbol standards). In business process analysis, a
couple of symbols are sufficient. A box with text inside indicates a step in the process,
while a diamond with text represents a decision point. See the figure for an example.
If the flowchart is too messy to draw, try starting again, but leaving out all of the decision
points and concentrating on the simplest possible course. Then the session can go back
and add the decision points later. It may also be useful to start by drawing a high-level
flowchart for the whole organisation, with each box being a complete process that has to
be filled out later.
From this common understanding can come a number of things - process improvement
ideas will often arise spontaneously during a flowcharting session. And after the session,
the facilitator can also draw up a written procedure - a flowcharting session is a good way
of documenting a process.
Process improvement starts with an understanding of the process, and flowcharting is the
first step towards process understanding.
MT 512: Programming Design Page no: 8
TYPES AND PSEUDOCODE
2.1 ALGORITHMS
The term algorithm originally referred to any computation performed via a set of rules
applied to numbers written in decimal form. The word is derived from the phonetic
pronunciation of the last name of Abu Ja'far Mohammed ibn Musa al-Khowarizmi, who
was an Arabic mathematician who invented a set of rules for performing the four basic
arithmetic operations (addition, subtraction, multiplication and division) on decimal
numbers.
An algorithm is a representation of a solution to a problem. If a problem can be defined
as a difference between a desired situation and the current situation in which one is, then
a problem solution is a procedure, or method, for transforming the current situation to the
desired one. We solve many such trivial problems every day without even thinking about
it, for example making breakfast, travelling to the workplace etc. But the solution to such
problems requires little intellectual effort and is relatively unimportant. However, the
solution of a more interesting problem of more importance usually involves stating the
problem in an understandable form and communicating the solution to others. In the case
where a computer is part of the means of solving the problem, a procedure, explicitly
stating the steps leading to the solution, must be transmitted to the computer. This
concept of problem solution and communication makes the study of algorithms important
to computer science.
Throughout history, man has thought of ever more elegant ways of reducing the amount
of labour needed to do things. A computer has immense potential for saving time/energy,
as most (computational) tasks that are repetitive or can be generalised can be done by a
computer. For a computer to perform a desired task, a method for carrying out some
sequence of events, resulting in accomplishing the task, must somehow be described to
the computer. The algorithm can be described on many levels because the algorithm is
just the procedure of steps to take and get the result. The language used to describe an
algorithm to other people will be quite different from that which is used by the computer,
however the actual algorithm will in essence be the same. An example of an algorithm
people use would be a recipe to make a cake.
"4 extra large eggs, beaten
1&1/2 C. stock
1/2 teaspoon salt
1 scallion, minced
1 C. small shrimp or lobster flakes
1 t. soy sauce
1 Tablespoon oil
1. Mix all the ingredients, except the oil, in a deep bowl.
MT 512: Programming Design Page no: 6
, 2. Put 1" water in wide pot, then place deep bowl of batter inside.
3. Cover pot tightly and steam 15 min.
4. Heat oil very hot and pour over custard.
5. Steam 5 more min. Serves 4 people"
This breaks down 'Making Chinese egg custard' into smaller steps. To make the product
one still needs to know how to execute each of the steps in the procedure and understand
all of the terms.
Definition:
A procedure is a finite sequence of well-defined instructions, each of which can be
mechanically carried out in a finite amount of time.
The procedure must break up the problem solution into parts that the recipient party can
understand and execute. In the case of a computer, the problem solution is usually in the
form of a program that encompasses the algorithm and explains to the computer a clearly
defined procedure for achieving the solution. The procedure must consist of smaller steps
each of which the computers understand. There may be no ambiguities in the translation
of the procedure into the necessary action to be taken. A program is then just a specific
realisation of an algorithm, which may be executed on a physical device.
A computer is essentially a physical device designed to carry out a collection of primitive
actions. A procedure is a sequence of instructions written in terms of which evoke a
proper operation. To make effective use of an algorithm on a computer one must not only
find and understand a solution to the problem but also convey the algorithm to the
computer, giving the correct sequence of understood commands that represent the same
algorithm.
Definition:
An algorithm is procedure consisting of a finite set of unambiguous rules (instructions)
which specify a finite sequence of operations that provides the solution to a problem, or
to a specific class of problems for any allowable set of input quantities (if there are
inputs). In other word, an algorithm is a step-by-step procedure to solve a given problem
Alternatively, we can define an algorithm as a set or list of instructions for carrying out
some process step by step. A recipe in a cookbook is an excellent example of an
algorithm. The recipe includes the requirements for the cooking or ingredients and the
method of cooking them until you end up with a nice cooked dish.
In the same way, algorithms executed by a computer can combine millions of elementary
steps, such as additions and subtractions, into a complicated mathematical calculation.
Also by means of algorithms, a computer can control a manufacturing process or co-
MT 512: Programming Design Page no: 7
, ordinate the reservations of an airline as they are received from the ticket offices all over
the country. Algorithms for such large-scale processes are, of course, very complex, but
they are built up from pieces.
One of the obstacles to overcome in using a computer to solve your problems is that of
translating the idea of the algorithm to computer code (program). People cannot normally
understand the actual machine code that the computer needs to run a program, so
programs are written in a programming language such as C or Pascal, which is then
converted into machine code for the computer to run.
In the problem-solving phase of computer programming, you will be designing
algorithms. This means that you will have to be conscious of the strategies you use to
solve problems in order to apply them to programming problems. These algorithms can
be designed though the use of flowcharts or pseudocode.
2.2 FLOWCHARTS
Flowcharting is a tool developed in the computer industry, for showing the steps
involved in a process. A flowchart is a diagram made up of boxes, diamonds and other
shapes, connected by arrows - each shape represents a step in the process, and the arrows
show the order in which they occur. Flowcharting combines symbols and flowlines, to
show figuratively the operation of an algorithm.
In computing, there are dozens of different symbols used in flowcharting (there are even
national and international flowcharting symbol standards). In business process analysis, a
couple of symbols are sufficient. A box with text inside indicates a step in the process,
while a diamond with text represents a decision point. See the figure for an example.
If the flowchart is too messy to draw, try starting again, but leaving out all of the decision
points and concentrating on the simplest possible course. Then the session can go back
and add the decision points later. It may also be useful to start by drawing a high-level
flowchart for the whole organisation, with each box being a complete process that has to
be filled out later.
From this common understanding can come a number of things - process improvement
ideas will often arise spontaneously during a flowcharting session. And after the session,
the facilitator can also draw up a written procedure - a flowcharting session is a good way
of documenting a process.
Process improvement starts with an understanding of the process, and flowcharting is the
first step towards process understanding.
MT 512: Programming Design Page no: 8
