Testing an Algorithm for a Numerical Sequence

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来自 Duke University 的课程

Programming Fundamentals

357 个评分

Duke University

Programming Fundamentals

357 个评分

课程 1（共 4 门，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.

从本节课中

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.

Testing an Algorithm for a Numerical Sequence3:15

与讲师见面

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're going to test the algorithm that we just wrote.

We're going to be counting from zero to N and N as a variable.

We're going to draw boxes for each of our variables to keep

track of what value they currently have as we step through our algorithm.

As we begin, N has the value, five.

The other thing we're going to keep track of is the output of our program.

Here is a box labeled, output,

and every time we write something down,

we're going to write it into this output box.

Finally, we're going to use a green arrow to keep track of where we are.

Right now, the arrow is right before the line that says count from zero to N,

which means we haven't done this yet. Now, we can start.

The first thing we want to do is count from zero to N inclusive,

and call each number that we're counting, i.

Since i is a variable,

and it's going to start with the value zero,

we create a box to hold i and its value of zero.

Now, we enter the next step.

The next thing we're going to do is write down N squared minus two times i.

We have a little bit of math to do here.

N is the value, 5,

and i has the value, zero,

so this gives us 25 minus zero or 25.

And again, we're supposed to write this number down,

so we place this number into our output box.

Now, this process is going to repeat again and again.

Now, i is going to have the value one.

Once again, we're going to compute N squared minus two times i.

This is the same as last time except i has the value of one.

This is 25 minus two or 23.

We write that to our output box.

Now, we just completed i equals zero,

and i equals one,

and we're trying to get all the way to i equals five.

So now, we're working on i with a value of two.

Once again, N squared minus two times i,

which is 25 minus four,

the value is 21, and we will write this to our output box.

Now, we're working on i with the value of three.

We're going to write down the number,

N squared minus two times i,

25 minus 6 which is 19,

into our output box.

And we're going to keep doing this.

For i having the value four, which is 17.

For i equals five,

which is 15. i keeps getting larger each time we step through our algorithm.

When i equals 6, however,

we're going to stop because we're only counting up to N equals five.

At this point, we finished the entire algorithm,

and the good news is that our answer matches what we were expecting.

The sequence of numbers is,

in fact, what we were hoping to produce.

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