Week002-Module Problem Solving Through Flowcharts PDF

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Week 2: Problem Solving Through Flowcharts 1
Lesson 2: Problem Solving Through Flowcharts 1 ...

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Computer Programming 1 Problem Solving through Flowcharts 1

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Module 002 Problem Solving through Flowcharts 1 “Creativity is the process of having original ideas that have value. It is a process; it’s not random.” –Ken Robinson. Have you encountered challenges before? How did you solve it? Were you successful in overcoming those challenges? If not, do you attribute your failure in your lack of planning and visualization of the situation? Those questions are our focus for these two consecutive modules about Problem Solving through Flowcharts. In this first of the two-part modules, you will learn about the art of problem solving, particularly in Computer Programming. To aid you with the conceptualization of your soon-to-be instructions that you will command the computer to do, you will create a visual aid called flowcharts. In addition to that, you will be exposed to the Research-standard syntax called Pseudocodes. At the end of this module, you will be able to: 1. 2. 3. 4. 5.

Identify the characteristics of problem solving in computer programming Identify and describe the symbols in flowcharting Identify the conventions in pseudocodes Organize a day-to-day process using flowcharts and pseudocodes Deduce the benefits and shortcomings of flowcharts and pseudocodes

Again, researching beyond the coverage of this module is highly encouraged to supplement your understanding of the topics covered. And as always, think and see beyond the box. So, what are we waiting for? Let us continue our explorationof the world of Computer Programming.

Course Module

Recall In the previous module, we talked about the field of Computing and Programming in general. We also enumerated the domains under Computer Development, namely: a. b. c. d. e. f. g.

Web Development Back-end Development Mobile Development Data Science Application Development API Development, and Embedded Systems Development

Lastly, we went through an overview of the infamous programming languages as of 2016: a. b. c. d. e. f. g. h. i. j.

JavaScript Java Python Ruby PHP C++ C# Go Shell Objective-C

Introduction Problem Solving is defined as the systematic approach in searching for a solution or set of solutions to a specific problem. This approach can be in any form such as by listing the possible options and choosing the most efficient of them, providing weights to all possible scenarios and choosing the most significant scenario, or applying small-scale to massive calculations to incorporate values to challenges and optimally solve those smaller challenges to complete the main problem. With addition of several other characteristics, in the context of Computer Science, this can be called algorithms. In this module, we will be taking the concept of Problem Solving in the context of Computer Programming; how to come up with the right solution to a given problem.

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Problem Solving in Computer Programming Problem Solving is the most essential skill that anyone venturing the field of Computer Programming needs. It basically says whether a specific challenge is worth solving given a finite time. However, what makes problem solving in Computer Programming different from the conventional problem solving are the characteristic that a solution to the problem should have met. Problem Solving in Computer Programming should satisfy the following characteristics: 1. 2. 3. 4. 5. 6.

Solvable Goal-oriented Verifiable Quantifiable Doable in finite steps Doable in current technological limitations

Problem solving in Computer Programming requires the problem to be solvable. This characteristic might seem to be an obvious requirement, but is tend to be overlooked in several ways. A famous quote from a 2009 American comedy-drama film “Up in the Air” says “It’s only a problem, if it has a solution.” This presents one aspect of solvable that focuses on the problem – there should exist at least one probable solution. It is unthinkable to process problems that pose no direct solutions. It is like playing NBA-sized basketball with tigers. That situation is designed for humans-only convention, whereas the subjects involved cannot in anyway be altered to satisfy the need of the situation in this very moment. Problem solving also requires the problem to be goal-oriented. A goal focuses the solutions to meet a specific one-path ending. Setting a goal to the problem-at-hand lets you identify several approaches and solutions. It also set a few limitations to which possible solutions are subjected to determine accept-reject criteria. Problem solving also requires the problem to be verifiable. It is impractical to provide solutions for problems where you cannot even verify the validity of your solutions. In addition, there is also the need to certify that there exist manyother criteria to make the solution fail and succeed. For example, we can have a slot machine that accepts only 5-peso and 1-peso coins be subjected to tests wherein you can attempt to insert 10-peso, 5-peso, 1-peso and 5-cent coins into the slot machine. The slot machine should then reject Course Module

the 10-peso and 5-cent coins in some defined way but accept the 5-peso and 1-peso coins. Problem solving also requires the problem to be quantifiable. It is unworkable in Computer Programming if the problem cannot be quantified in any scale possible. For instance, we have a problem which is about determining the acceptance rating of a proposed Thesis title. This problem can be solved through Computer Programming provided a qualifying criterion is provided. However, if tasked to provide solution for a problem to classify which of the given inputs is fake and which is real. Problem solving also requires the solution to be doable in a finite number of steps. We live in a world of limited resources. One of those resources concerned in Computer Programming is time. It is highly impractical to provide a solution that takes a million of hours to complete. In addition to time, computers have a limited amount of allocated resources, namely: RAM, storage and processing power. Maxing out these resources just for a solution is not only impractical but also useless. Lastly, problem solving also requires the problem and solution to be doable within the limits of the current technology. In computer programming, we simply reuse the resources currently at hand. Relying on other resources that either does not yet exist or is impossible to get our hands on is proven to be unintelligible. We do not concern ourselves with what will probably be available in the future since Computer Programming aims for practicality over theory. We have Computer Science for those regards.

Flowcharts Essentials Now that we have a set of characteristics which we can use to determine the viability of problems and possible solutions in terms of Computer Programming, we now should be able to present our solution in a visual format called flowchart. Flowchart is a visual aid showing a sequence of actions or operations involved in Computer Programming. Flowchart helps computer programmers in visualizing their thought solution which helps them visually relay their low-level solution and helps to identify key aspects of the solution which can pose problems given a specific combination of inputs and outputs. Figure 1 shows a sample of a flowchart which illustrates the process of going to school using one of the two transportation systems available, the bus and the subway.

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Figure 1. Lau, J and Chan, J. (2017). [G05] Charts & Diagrams [Online Blog]. Retrieved from http://philosophy.hku.hk/think/strategy/chart.php

The flowchart in Figure 1 shows almost all the fundamental elements used in flowcharting. That flowchart solves the problem of going to school by choosing an appropriate transportation system based on time. Let us go through the process in the flowchart. The flowchart starts with the student leaving home. After leaving, the student needs to choose the best transportation system he will take to arrive at his school.

Based on the given flowchart, we can assume that there is a heavy buildup of traffic past 7 AM. It is therefore a better choice to take the subway if the time is past 7 AM.

The student then needs to check the time whether it is already past 7 AM. If not, he can still choose bus as his transportation vehicle. If it is already past 7 AM, he needs to take the subway to arrive at school on time. After taking the best transportation system, the flowcharts end with the student arriving at school on time.

Course Module

You might have noticed that the flowchart uses two distinct symbols for checking the time and deciding what action to do. This is essential in Computer Programming. You need to learn how to identify distinct actions. The act of checking the time is totally different from deciding which action to do. Although it is tempting to simply combine the two actions, the computer will still read them as two distinct actions. Hence as a promising computer programmer, you need to be able to personally identify such easily missed distinctions and act accordingly as how the computer will interpret those instructions. Knowing this will not only make your codes easy to read, but also optimize your codes.

Symbols used in Flowcharts Flowcharts use a defined set of symbols to represent a specific action performed. Those symbols are used like how you will use Lego bricks to build something. In Computer Programming, those symbols are combined in a specific manner to build an application, for example. One thing to note for the symbols is like a set of Lego bricks, symbols should be used in a manner that fits the requirements of the solution to create a logical flow of actions (i.e. instructions for the computer). Symbol

Name

Description

Terminator

A symbol used to indicate the beginning or the end of the process flow

Process

A symbol used to indicate a specific action done

Preparation

A symbol used to prepare data or initialize something

Data

A symbol used to retrieve value from the user as input or present value to the user as output

Decision

A symbol used to identify which of the two possible paths will be taken based on the conditions set inside

On-page Connectors

A symbol used to connect two or more symbols belonging to the same page together to form a continuous process

Off-page Connectors

A symbol used to connect two or more symbols belonging to the different pages together to form a continuous process

Table 1. Basic Symbols in Flowcharting

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The symbols in Table 1 are connected by a line with one and only one arrow head, usually called arrow. In Mathematics, this is a ray with no suggestive prominent endpoint. The arrow head determines the flow of the process, where next symbol to read is.

Process 2

Process 1

Figure 2. Partial Flowchart Showing the Progression of Symbols

Figure 2 shows the progression of symbols using the arrow. In the figure, Process 2 is executed first before Process 1 despite their naming. The arrow is the sole indicator of the progress.

A

Process 1

Process 2

Process 3

Process 4

A

Figure 3. Partial Flowchart Showing another Progression of Symbols

Figure 3 shows a more complex progression using arrows. In this figure, Process 1 is executed first, followed by Process 2, then Process 3. In Process 3, the arrow points to Process 4 which is pointed back to Process 1. This specific example is a non-terminating process which should be avoided in actual programming design.

Course Module

Standards in Flowcharting Now that you know the different symbols used in creating your flowcharts, you need to adhere to the standards used in writing flowcharts. In this section, you will learn the different standards in flowcharts which should aid you also in writing your codes in the future. These standards were set not to limit you with the usage of the symbols, but to give you freedom in setting your logic for writing computer instructions through computer programming.

START

…

END Figure 4. Start Terminator and End Terminator

Flowcharts should always have two (2) and only two terminator symbols, namely the Start terminator and the End terminator. The Start terminator always starts the entire flowchart sequence. It should always be the first symbol found at the top-most of all flowcharts. If the flowchart sequence is multi-paged, the Start terminator is found at the first page. The End terminator always ends the entire flowchart sequence. It should always be the last symbol found at the bottom-most of all flowcharts. If the flowchart is multi-paged, the End terminator is found at the last page.

Is 1 > 2

No

Yes Figure 5. Decision Symbol with Yes and No Scenarios

Decision symbols always have two (2) possible scenarios, the YES and NO. Since the Decision symbol contains a specific condition, that condition should always be answerable by YES or a NO. If the condition is not answerable by a YES or a NO, the condition should be rephrased to adhere to standard regardless of the number of nested Decision symbols to be made. This is the case for the Decision symbol since the computer can only process one

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condition at a time. For example, if you asked “which color did the user pick?”, the computer will process that with a series of question like “Is it Blue?”, “Is it Red?”, and so on. The computer will not directly check for the answer like “The user definitely chose Red” without checking for the rest of the possible answers.

Inputv

Figure 6. Data Symbol with Out-going Arrow

END Figure 7. End Terminator without any Out-going Arrow

Flowchart symbols should always have one (1) and only one out-going arrow. Since the arrow signifies that there is a progression of flow, it is a requirement that symbols should only have one arrow to other symbols. We are limiting our thinking to single-threaded flow. Hence, a symbol can only be succeeded by only one symbol. The exceptions to this are the End terminator and the Decision symbol. The End terminator marks the end of the flowchart; therefore, there is no logical need for it to have an arrow. The Decision symbol has two possible scenarios; therefore, there are always two (2) and only two arrows.

Outputv Figure 8. Data Symbol with many In-going Arrow

START Figure 9. Start Terminator without In-going Arrow

Course Module

Flowchart symbols can have any number of in-going arrows. Since most symbols can start from any of the other symbols, it is logically accurate to allow any number of in-going arrows. However, there is only one (1) symbol that does not allow any in-going arrow – the Start terminator. The Start terminator marks the start of the entire flowchart; therefore, there is no logical reasoning to connect other symbols to the Start terminator. Should there be a need to restart the entire flow, the symbol should connect to the symbol with an in-going arrow from the Start terminator.

START

x=1+1

END Figure 10. Flowchart Layout

Flowcharts are written from top to bottom. With the Start terminator at the top, the next symbols should be placed below the Start terminator, and the next below the previous symbol. There exist some symbols beside a symbol, which is the case for the Decision, On-page Connector and Off-page Connector symbols. Flowcharts should not have any out-going arrow pointed upwards. This is for creating a seamless flow process. For complex flowcharts supporting upward out-going arrows, determining the connection between the symbols will prove to be difficult. Hence, there is the need for this standard. Should there be a need to connect to other symbols found at the top of the sequence, you can use On-page and Off-page Connector symbols. Lastly, flowcharts should not have any overlapping arrows. This is for emphasizing clarity. Having overlapping arrows creates ambiguity in the direction of the arrows intersecting and their respective symbols.

Pseudocodes Pseudocodes are not Academe-standard for expectant undergraduate students. However, there is a growing demand in the usage of pseudocodes not only in the Academic sector, but also the Research sector.Pseudocodes are

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high-level description of the processesin Computer Programming.Their format varies by writer. Some are English-like to accommodate non-technical audience. Some are written close to the actual syntax used in the source code to accommodate technical audiences and Research critics. DECLARE name SETnameAS “Charlotte” APPEND “ Queens” TOname APPEND “ B.A.” TOname OUTPUT name Figure 11. Sample Pseudocode

Course Convention Pseudocode are generally user-centric and no defined standard for writing them. However, for the ease of the codes to be written in the future modules and for the ease of understanding for your peers, we will set a convention in writing pseudocodes. This should enable us, together with your peers and mentors, to talk using only one language. Keyword DECLARE

Usage DECLAREv, a[]

Description A keyword to signify we are about to declare a variable v and an array a

NOTE: Variables and arrays will be discussed in the coming weeks. For now, think of a variable as a word that represents something, and an array as a word that represents a series of anything. SET…AS…

SETvariable1ASvalue1, variable2ASvalue2

APPEND … TO …

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A keyword to set values to variables

APPENDvalue1TOvariable1, A keyword to insert String values at the end of a variable value2TOvariable2 containing a String

IF … THEN … [ELSE IF … THEN …

IFcondition1THEN statements1 END

-

or -

ELSE …] END

A keyword to limit selected statements from being executed only when the specified condition was met

NOTE: Conditions and statements will be discussed in the coming weeks.

IFcondition1THEN statements1 ELSE statements2 END

-

or -

IFcondition1THEN statements1 ELSE IFcondition2THEN statements2 ELSE statements3 END WHILE … DO …

WHILEcondition1DO statements2

A keyword to limit selected statements from being executed repeatedly until the specified condition becomes false

LOOP

LOOP

OUTPUT …

OUTPUTvariable/value

A keyword to display a value or a value of a variable to the user

INPUT …

INPUTvariable

A keyword to accept any value from the user and save it to a variable

CALL …

CALL function/subroutine

A keyword to call a user-defined or external function

NOTE: Functions and subroutines will be discussed in the coming weeks Table 2. Pseudocode Keywords

For you to understand pseudocodes better, let us use the sample flowchart at Figure 1. Remember that in the sample flowchart, the problem being solved

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