Name: SPELLER IS EASY (IN PYTHON) - CS50 on Twitch、EP.1 (SPELLER IS EASY (IN PYTHON) - CS50 on Twitch, EP. 1)
Uploaded: 2021-01-14T10:28:44.000Z
Duration: 1 h 31 min 33 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

DAVID MALAN: So this is a new approach for us.

We, of course, have lectures once a week here in Cambridge.

And of course, we've done a number of live streams over the past few years.

But we thought we'd try something new with our Twitch channel here.

He's quite the gamer himself, and a programmer of games.

And we thought we'd use this as a more interactive time to actually chat with

some folks in the Twitch chat room, and actually walk through some code in real

to get into more depth on some of the things

that we might otherwise talk about in class, and then, ultimately,

take people's questions and steer the conversation in any direction folks out

Everybody who's in, feel free, definitely, to chime today and chat.

If you aren't following the CS50 TV account,

I believe there's a 10 minute waiting period.

So definitely follow us so you can talk to us.

But I see we do have one person, Srini Vasank says hello.

I guess we can take a little transition here

to your laptop where we have your code there.

Yep, so we're actually sitting here in Cambridge, Massachusetts

on Harvard's campus with a magical green screen behind us.

And so we're superimposing ourselves, the two humans,

which is why you see this nice glow on both of us today.

COLTON OGDEN: I wish I had a shot of just the green screen.

DAVID MALAN: That's green, but you see it as gray, perhaps.

And this allows us to superimpose ourselves over the code,

like you've seen in some other channels, so that we can actually

COLTON OGDEN: We do it for lecture for the code it itself.

And we use some camera magic to actually capture it across the room as well.

DAVID MALAN: All right, anymore hellos to tend to?

our first trial of this is-- take a closer look at one of the topics

Those of you have been following along for some time

and are pretty much through half of the course

or so might have implemented your own spell checker at some points.

And for those unfamiliar, roughly halfway during CS50's semester

here on campus and online, we challenged students

to build their own spell checker, which is a piece of software that looks over

all the words you've typed out in a file,

and tells you, often with read underlines, which words you've

That dictionary is just a really big list of words,

And it's a non-trivial problem to actually look up

every one of the words in your file against every word in the dictionary.

If you recall from our discussion of asymptotic notation,

that's like an n squared problem, if n is the number of words in each,

And that can actually take quite a bit of CPU cycles and memory.

And so one of the challenges in CS50 is, do that efficiently.

Minimize your use of CPU time, so to speak.

And just write the fastest spell checker possible.

Now, what language, of course, do we tend to write this in though?

COLTON OGDEN: Well we start it in C, generally, for the course.

And really takes advantage of the hardware.

But what are some of the prices you'd say you pay by writing stuff in C?

COLTON OGDEN: Programmer time would be number one.

Obviously looking for memory leaks, and seg faults,

and all those sorts of things that trip up a lot of programmers.

DAVID MALAN: Yeah, those of you programmed in C, maybe C++,

have dealt with pointers, memory addresses, segmentation faults,

Why don't we actually take a look at what it is you have had to do,

or if you're following along with CS50 for the first time,

might have to do if you tackle this particular problem down the road.

And then let's actually do it in a much more friendly environment of Python.

But consider what prices we actually pay for doing that.

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SPELLER IS EASY (IN PYTHON) - CS50 on Twitch、EP.1 (SPELLER IS EASY (IN PYTHON) - CS50 on Twitch, EP. 1)

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