Testing a Pattern of Squares

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Из курса от партнера Duke University

Programming Fundamentals

302 оценки

Duke University

Programming Fundamentals

302 оценки

Курс 1 из 4 — Specialization Introduction to Programming in C

Programming is an increasingly important skill, whether you aspire to a career in software development, or in other fields. This course is the first in the specialization Introduction to Programming in C, but its lessons extend to any language you might want to learn. This is because programming is fundamentally about figuring out how to solve a class of problems and writing the algorithm, a clear set of steps to solve any problem in its class. This course will introduce you to a powerful problem-solving process—the Seven Steps—which you can use to solve any programming problem. In this course, you will learn how to develop an algorithm, then progress to reading code and understanding how programming concepts relate to algorithms.

Из урока

Introduction

This module introduces a powerful process for solving any programming problem—the Seven Steps. You will learn how to approach a programming problem methodically, so you can formulate an algorithm that is specific and correct. You will work through examples with sequences of numbers and graphical patterns to develop the skill of algorithm development.

A Pattern of Squares4:46

Testing a Pattern of Squares2:21

Drawing a Rectangle4:07

Closest Point5:07

Generalizing Closest Point5:07

Познакомьтесь с преподавателями

Andrew D. Hilton
Associate Professor of the Practice
Electrical and Computer Engineering
Genevieve M. Lipp
Adjunct Professor
Electrical and Computer Engineering/Mechanical Engineering
Anne Bracy
Senior Lecturer
Computer Science, Cornell University

In this video, we will test the algorithm

for a pattern of blue and red squares on a grid.

Remember that testing is going to make us more confident in our algorithm,

since generalizing is one of the harder parts of the programming process and is

prone to errors such as leaving something constant that should be a variable.

We need a grid to draw on,

an arrow to keep track of where in the algorithm we are,

and a box to list our variables in.

Let's use two for our value of N. We make a box for x and start counting at zero.

Then we make a box for y and start counting at x's value which is zero here.

Now, we need to decide if x plus y is a multiple of three.

It is, so we go inside the if statement and put a blue square at zero, zero.

Now, there are no more steps for this iteration of y,

so we continue counting with y equals one.

Zero plus one is not a multiple of three,

so we enter the otherwise clause and put a red square at zero, one.

There are no more steps for this y,

so we'll count the next one.

Zero plus two is not a multiple of three,

so we'll put a red square at zero, two.

We continue counting, and y is three.

But we were only counting from x to N so we don't do any of these steps.

And we continue counting for x,

so now, x is one.

We're going to count from one to N and call that y.

One plus one is not a multiple of three,

so we put a red square at one, one.

Incrementing y, one plus two is a multiple of three,

so we put a blue square at one, two.

We're done counting for y,

so next, we count our next x.

Counting from two to two,

two plus two is not a multiple of three,

so we put a red square.

We finished counting for y,

so we count for the next x.

We're done counting for x since we only want to count to N which is two.

So we're done with the counting,

and we finished executing this algorithm.

We are done, and we found the answer we expect.

We can say our algorithm,

at least, works for N equals 2.

We're a little bit more confident in our algorithm because we've shown it to be

correct for at least one value of N that was not what we used to come up with it.

If we wanted to be more confident,

we would have to test it more thoroughly.

As always, testing can't prove that it's correct,

it can only make us more and more confident.

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