Name: 2019年律師行業CS50--計算思維篇 (CS50 for Lawyers 2019 - Computational Thinking)
Uploaded: 2021-01-14T10:20:44.000Z
Duration: 54 min 50 s
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DAVID MALAN: So odds are you know someone who is or perhaps are

反身代名詞

Well I propose that a computer person is simply

someone who's really good at computational thinking.

Thinking methodically, or more formally, thinking algorithmically,

whereby you take inputs to some problem, you solve that problem

and produce output, but you do so step by step by step, along the way

defining any of the terms or ideas that you

need to use so that anyone else following along

can understand exactly what it is you're doing.

Computer science itself is really about computational thinking, then.

It's not about programming, with which it's

often conflated, although programming is a wonderfully useful tool with which

you can solve problems, but computer science itself

And it can be in any number of domains, whether it's

software or hardware or artificial intelligence or machine learning

That's the wonderful thing about computer science--

it's just so wonderfully applicable to other fields.

It's all about equipping you with a mental model,

so to speak, a set of concepts, as well as

some practical skills via which you can bring to bear solutions

Now what, though, does it mean to solve a problem?

I propose that we think about problem-solving quite simply as this.

If you've got some problem to be solved, you have an input.

And the goal is to solve that problem and come up with some solution, which

And in between those inputs and outputs hopefully

are the step-by-step instructions via which we can solve that problem.

Now how we're going to solve that problem we'll have to come back to.

For now we'll consider it to be the proverbial black box.

So we don't quite know or need to know right now just how it works,

but that it can work, and we'll come back to this soon.

But for now, we do need a way to represent these inputs,

and we do need a way to represent our outputs.

Right now I happen to be speaking English

and you happen to be hearing English, and so we've sort of

tacitly agreed that we'll represent our words using this particular language.

Now computers tend not to use English, they have their own system,

if you will, with what you might be familiar even if you don't quite

speak it yourself, and indeed, there are different ways

For instance, let's consider the simplest of problems-- for instance,

I don't need computers or English, I can simply use my physical hand and say,

I'm starting with zero people and now I'll

count one, and then two, and then three, and then four, and then five,

I'm out of fingers, but I can at least employ my other hand, maybe

a couple of feet and get as high as 10, maybe even

This is pretty equivalent, actually, to just keeping

score counting the old-school way with hash marks.

Right now we've not counted anything, but as soon

as I start drawing some lines, I might represent the number 1,

Or by convention I can draw a slash just to make super clear that this is now

representing 5, and then I can do another five of those

Now these systems of hashes, as well as this system of counting on my fingers,

Uno implying one, simply signifying that I only have one digit--

pun not intended-- via which I can count things.

This takes the form of my fingers on my hand or these hash marks on the screen.

But it doesn't get me very far, because of course

on my one hand with five fingers, I can only count up to five total.

And even on the board it feels pretty inefficient, because for every number

I want to count higher, I have to draw yet

another line on the screen, which just continue to accumulate.

But suppose we were a little more clever about this

and we thought about this problem from a different angle.

Maybe I could take into account not just the number of fingers

that I've raised, but the order in which I've raised them

or the pattern via which I've permuted them rather than just taking

If I take that approach, maybe I can actually count even higher than five

on just one hand before resorting to another hand or feet.

Well instead of counting up 0 to 1 to 2 to 3 to 4

to 5, why do I instead start with some patterns instead?

So I'll still start with 0, I'll still start with 1, but now for 2,

I'm not just going to raise the second finger,

I'm instead going to go from 0 to 1 to 2,

putting down that first finger or thumb, simply representing 2

And when I'm ready to represent the number 3,

And so using just two fingers now have I represented four possible values--

From 0 to 3, of course, is four total values,

and so I've counted as high as 3 now using not three fingers, but only two.

Well, I just need to raise an additional finger.

And so let's start at 0, to 1, to 2, to 3, to 4-- whoops--

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2019年律師行業CS50--計算思維篇 (CS50 for Lawyers 2019 - Computational Thinking)

ultimately

context

physical

pattern