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[ Music ]

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>> This is CS50 and this is
this year's Fall 2010 teaching

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fellows and course assistants.

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If we could, a big round
of applause for them.

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[ Applause ]

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>> Two of them in particular
are graduating this year,

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namely the course's
head teaching fellows,

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Yukhi Yamashita and Cansu
Aydede, both of whom have been

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with the course for
three years now as staff.

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In fact, Yukhi didn't
start as one

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of our head teaching fellows.

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He was a teaching
fellow in Fall 2008,

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having just taken CS50 the year
before, and he made the mistake

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that fall of being a go-getter
and e-mailing me a nice

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and polite list of all of
the typographical errors

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in one of the problem sets.

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But I thankfully took
this the right way

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and immediately promoted him
to the position he has now had

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with Cansu for a
couple of years,

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and it is because of
Yukhi Yamashita, frankly,

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that this course looks as
pretty and as sexy as it does,

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given that he is our designer.

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So for Yukhi in particular,
a round of applause.

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[ Applause ]

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>> So if we do this right, Cansu
Aydede is likely to shriek,

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because anytime she gets
public recognition she seems

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to do this.

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In fact, when she was herself
a freshman in Fall 2007 was

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when we first met,
and I met her over one

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of the Annenberg
Student Faculty Dinners.

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And we got to chatting
and she was self avowed,

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one of those less
comfortable, dare say one

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of those least comfortable,
in her own words.

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And so for some reason, though,
this conversation caught my eye.

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She cared about CS50, she loved
CS50, and even though she,

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like many of you, had stories
about working in the basement

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of the Science Center
'til all hours,

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she nonetheless stuck
it through.

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And now she is about to
graduate as well as a senior,

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having been the course's
head teaching fellow now

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for three years, the first and
to my knowledge to have started

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that role, as a sophomore
at the college,

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head of one of the largest
college courses here.

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And for that and
for her leadership

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over the past several
years am I hugely grateful.

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So to Cansu as well.

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[ Applause ]

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>> So even though it just
is me that you tend to see

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or not see a couple
of times a week,

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there are definitely
a few other folks we'd

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like to thank right here from
the get-go, namely the folks

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that run this course
behind the scenes.

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Besides the TFs, besides
the CAs, besides myself,

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we have two individuals here,

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Chris and Hugh running
cameras every day.

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We have Barry in back.

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We have the Memorial
Hall team downstairs,

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the folks in the classrooms
across the university,

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and it is by no means
an easy feat

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to book some 40-plus
sections this fall.

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So to all of you and to
those behind the scenes,

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thank you all so very much.

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[ Applause ]

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>> So, about that quiz.

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So it was not the emotional
note I really wanted us

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as a class to end on.

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It was admittedly a
bit on the long side.

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But realize that as many times
as we've said verbally in class

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and the syllabus and my
e-mail this past week,

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it really is one's
relative trending

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in the course that we look to.

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And even though your
percentage on something

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like this might not be as
high as you would have liked,

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maybe not even as high as
it was on the first quiz,

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that really is sort of
immaterial to the progress

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that you've made, to the
work that you've submitted.

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In CS50 we really
do pride ourselves

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on making it a very much
individualistic course

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at semester's end.

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I really do have this
semester, will have,

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some 500 conversations
over e-mail or in person

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with the teaching fellows.

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And if you read the
Crimson last spring,

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frankly if it were entirely
by the course's choice,

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we would do away with
grades altogether,

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since I think it's
very easy to lose sight

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of what's really
important in here.

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And so hopefully today as we
conclude this course and you see

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where you began and where you're
ending up and just a couple

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of week's hence where
you'll finish the course

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as CS50 graduates, hopefully
you'll really feel that delta

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between week 0 and week 12.

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So with that said, let us
forge ahead with today.

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You recall from week 0 if
you shopped us that we served

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up a little cake like this.

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Back in the days when
you were all newbs,

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so to speak in week 0.

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We went through our
problem set 0 submissions.

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Recall we did scratch back then.

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And one of our shoppers actually
submitted this story of sorts,

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which we thought we would begin
today's retrospective with.

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So this is by a former CS50
student, Damen, and here we go.

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[ Music ]

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>> Thank you to Damen.

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So speaking of phone books,

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we do seem to have
an infinite supply.

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We thought we'd see just
how much we've retained

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this semester.

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If we could get a couple
of volunteers up here

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to somehow involve
these phone books.

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Any takers?

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Anyone? Yeah, come on
down, very excitedly.

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What's your name?

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Oh. And who will match wits
here with the second phone book?

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Give me one person.

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If we're not going to
get anyone, numb up.

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Come on, down, right
here in front.

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Yep, second -- I'll take either
of you, whoever is least.

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Okay. What's your name?

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>> Herb.

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>> All right, you of course have

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to be comfortable
here on camera.

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What's your name
for the audience?

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>> Schwenn.

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>> Schwenn?

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>> Yeah.

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>> Here we have Schwenn
and we have Herb.

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The goal at hand is to find Mike
Smith in this here phone book.

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Herb, you've been nominated
to use linear search.

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Schwenn, you've been
nominated to use binary search,

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but in order to tear these
problems in half in the case

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of binary search you
must literally tear --

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and even in the case of linear
search, as you begin to search

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for Mike Smith, must you tear
each of your pages out linearly.

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Perhaps as a group.

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On your marks, get set, go.

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[ Background noise ]

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>> Oh, I did the
yellow pages, oh.

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[ Background noise ]

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>> The winner!

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[ Applause ]

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>> So if you didn't notice,
cleversteristic though it was

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for Herb to start at the end,

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the end of the phone
book is the yellow pages,

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which don't have humans.

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It's the beginning, of course,

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that starts with
the white pages.

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But sometimes optimizations
do not work out so well.

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So we started the semester
with some newb cake.

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We will end the semester
with some leete cake.

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In fact, thanks to teaching
fellow Rose Cal, who e-mailed me

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at like 7 a.m. this morning
after having e-mailed me

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at like 11 p.m. last
night saying she was going

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to Maxwell Dworkin to
decorate the cakes.

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The result is as of a few
minutes ago, not just this cake

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but this cake, and
also this cake here.

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Unfortunately these have now
been cut into 450 pieces,

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so that's the last
you'll see of the design,

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but there's a little
frosting for each of you.

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Also being handed
out after today,

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so there will indeed be cake in
a little bit of time downstairs

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in the pub as you guys exit
today, but also being handed

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out if you didn't
request one already,

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are these so-called shuttle boy
cards, our sort of throw-back

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to old school technology,
namely a piece of plastic card

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that you can put in your wallet.

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Now, it wasn't really the
plan to hand these out,

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useful as they are
for the calendar year

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at the end of the semester.

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This was the result of
some production delays,

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whereby we were trying
to save some money.

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We outsourced the project
to a company in China.

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Unfortunately I don't
speak Chinese,

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so ordering generally amounted
to my emailing Yuhki, who does.

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Yuhki would translate
to Chinese, email China,

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China would reply, Yuhki
would translate back.

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I would actually leave it
in my inbox for two weeks

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and then reply again,
and then finally,

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did our several thousand
shuttle boy cards come, finally.

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So if you already filled out
the form a few months ago,

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they went out by mail
already, but the TFs

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and CAs will also
have them downstairs.

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So now we have a little
something special.

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You've actually seen now
this gentleman before,

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so you can now put
a face to the name.

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But this is a first.

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Just late last night, one

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of our teaching fellows
received a submission via one

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of your classmates under
a pseudonym announcing

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that he had just printed
his own CS50 song.

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Let me go ahead and introduce
this by saying in a moment,

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you are about to hear Pranksta
a/k/a CS50 song by Shwyntax,

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and Shwyntax is releasing is
debut mixed tape tomorrow,

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11:23 to the Internet
called Cointoss.

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Check him out on
Facebook or Soundclad.com,

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to download some free music.

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So I give you one of
your very own classmates,

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Shwyntax, and his take on CS50.

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Listen close here to the lyrics.

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[ Music ]

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>> It's cs 50 AKA computer
science 50, let's break it down.

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I got a lot of codin
to do before tonight,

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and I aint got time to waste.

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let's get it.

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You say you a hacka but
you never crack nothing.

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We say you a pranksta and
you need to stop frontin.

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You just an amateur,
sometimes I wonder bruh,

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if n 2 is actually ya
runtime average huh?

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need a debugger man?

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you made a bad program I'll be
your gdb, jus lemme offer help

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for free Your style's so
fine, and so is ya design

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But the correctness deserves a
1 outta 5 malloc'in every line,

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like it's a pastime chock
full a Memory leaks,

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check with a valgrind

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segfault from for
loops, I fixed it

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00:16:03,016 --> 00:16:10,056
for you wanna make a hash
function tell me what you

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gon do?

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I I gotta go home, so try that
on ya own To me C is easy,

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but to you it's tough,
so: You say you a hacka

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but you never crack nothing.

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We say you a pranksta and
you need to stop frontin.

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You go on the internet
but you neva hack nothing.

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We've been programmin a long
time and you aint got nothing.

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You say you a hacka but
you never crack nothing.

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We say you a pranksta and
you need to stop frontin.

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You go on the internet
but you neva hack nothing.

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We've been programmin a long
time and you aint got nothing.

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DAAAMN homie, in high school
you was the MAAAAN homie,

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but what happened to you?

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I got the sickest work ethic,
when I code I don't sweat it Try

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to compete with me ever,

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listen you betta forget it Now
jus remember that this fall,

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told ya that I do it all, PHP
and javascript, CSS, mySQL

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You must be a pre-med,

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always run to the TF Psets come
you always cower, that's why you

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in office hours Now you think
you ready to work wit me

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on the final project But
we both know that Imma say

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"ummm not yet" I know
the truth must hurt,

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work at ya comfort now otherwise
guess what I'll tell ya what's

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worse, now:

241
00:17:12,226 --> 00:17:19,526
You say you a hacka but you
never crack nothing We say you a

242
00:17:19,696 --> 00:17:28,326
pranksta and you need to stop
frontin You go on the internet

243
00:17:28,326 --> 00:17:31,496
but you neva hack nothing We've
been programmin a long time

244
00:17:31,526 --> 00:17:32,126
and you aint got nothing.

245
00:17:32,156 --> 00:17:33,626
You say you a hacka but you
never crack nothing We say you a

246
00:17:33,656 --> 00:17:35,306
pranksta and you need to stop
frontin You go on the internet

247
00:17:35,336 --> 00:17:36,836
but you neva hack nothing We've
been programmin a long time

248
00:17:36,866 --> 00:17:37,976
and you aint got nothing
HAHA...DAAAMN HOMIE!

249
00:17:38,516 --> 00:17:54,586
[ Inaudible ]

250
00:17:55,086 --> 00:17:55,396
>> Shwyntax!

251
00:17:56,516 --> 00:18:01,916
[ Applause ]

252
00:18:02,416 --> 00:18:04,156
>> The single will be
available for download

253
00:18:04,156 --> 00:18:06,666
after today on CS50.net.

254
00:18:07,156 --> 00:18:09,896
So a quick look at what's ahead.

255
00:18:09,896 --> 00:18:12,646
So your feedback throughout this
semester, knowing though all

256
00:18:12,646 --> 00:18:13,526
of those surveys are,

257
00:18:13,526 --> 00:18:15,336
do you realize the
data is not for naught.

258
00:18:15,336 --> 00:18:17,996
We do absorb all of this
data, fine-tune the course

259
00:18:17,996 --> 00:18:19,836
so that your descendants
in this course

260
00:18:19,836 --> 00:18:22,196
in Fall 2011 will
hopefully benefit

261
00:18:22,196 --> 00:18:24,236
from your experiences
both good and bad.

262
00:18:24,236 --> 00:18:27,496
In particular we are going
to finally, after 21 years,

263
00:18:27,496 --> 00:18:29,416
exit the basement of
the Science Center,

264
00:18:29,416 --> 00:18:32,406
which has never been a terribly
fun place to spend the evening

265
00:18:32,406 --> 00:18:34,356
and move ourselves
sort of physics style,

266
00:18:34,616 --> 00:18:37,116
to multiple undergraduate
houses in the fall.

267
00:18:37,116 --> 00:18:39,146
We will bolster brain
break as well,

268
00:18:39,146 --> 00:18:41,986
and so we as CS50 students
will come more food

269
00:18:41,986 --> 00:18:43,016
in some of the houses.

270
00:18:43,046 --> 00:18:46,106
So stay tuned for that
and we hope that enhanced

271
00:18:46,106 --> 00:18:48,856
with a few workflow
improvements, office hours

272
00:18:48,856 --> 00:18:53,186
in future, so where you
can now see your successors

273
00:18:53,186 --> 00:18:55,986
in this course, will be
all the more an efficient

274
00:18:55,986 --> 00:18:57,826
and all the more a
social experience,

275
00:18:57,826 --> 00:18:59,306
much more so than cubicles

276
00:18:59,306 --> 00:19:01,876
under fluorescent lights
have ever allowed us.

277
00:19:01,876 --> 00:19:04,566
Recall that last week we
took a look at life after 50,

278
00:19:04,566 --> 00:19:06,576
specifically looking at
some of these courses here,

279
00:19:06,796 --> 00:19:09,726
every one of which
you can advance

280
00:19:09,726 --> 00:19:12,606
to after having only
CS50 under your belt.

281
00:19:12,606 --> 00:19:15,706
If you missed any part of that
week, realize we've chopped

282
00:19:15,706 --> 00:19:18,716
up that lecture into 10 minute
segments so that you can focus

283
00:19:18,716 --> 00:19:20,646
on just one or more
of these courses.

284
00:19:20,896 --> 00:19:22,616
Recall, too, from the handout,

285
00:19:22,736 --> 00:19:26,656
CS50.net/guide is the
CS50 unofficial guide

286
00:19:26,656 --> 00:19:27,786
to CS at Harvard.

287
00:19:27,786 --> 00:19:29,616
And you'll see this
little chart that tries

288
00:19:29,616 --> 00:19:30,676
to help you make sense

289
00:19:30,676 --> 00:19:34,106
of an otherwise unwieldy course
catalog and navigate your way.

290
00:19:34,106 --> 00:19:37,056
This is not to say that
we expect or are trying

291
00:19:37,056 --> 00:19:39,856
to convert all of you into
computer science concentrators.

292
00:19:41,096 --> 00:19:42,766
We are trying to
convert most of you

293
00:19:42,766 --> 00:19:45,666
into computer science minors,
admittedly, but with that said,

294
00:19:45,666 --> 00:19:49,136
the minor requires just 3
additional courses beyond CS50.

295
00:19:49,136 --> 00:19:51,426
So even if you need a little
bit of a breather this spring

296
00:19:51,426 --> 00:19:54,286
if not a senior, do
realize that there are

297
00:19:54,286 --> 00:19:56,786
so many different exciting
direction to go in.

298
00:19:56,786 --> 00:19:59,726
And that's really what resonated
with me after finishing CS50.

299
00:19:59,726 --> 00:20:02,366
It's very easy to sort of
get tunnel vision and think,

300
00:20:02,456 --> 00:20:05,176
CS is just about
programming, and that can be.

301
00:20:05,176 --> 00:20:07,876
But as we said in week 0,
it really is just a tool

302
00:20:07,876 --> 00:20:10,576
that you can use to explore
networking and hardware

303
00:20:10,726 --> 00:20:12,006
and visualizations

304
00:20:12,006 --> 00:20:13,646
and programming languages,
databases.

305
00:20:13,646 --> 00:20:15,736
There's so many different
directions, and especially

306
00:20:15,736 --> 00:20:17,586
for those of you
considering a minor,

307
00:20:17,586 --> 00:20:19,606
even if your concentration
is in the humanities,

308
00:20:19,866 --> 00:20:22,646
realize you'll still have a
chance to get some depth in one

309
00:20:22,646 --> 00:20:24,596
or more areas of
interest to you.

310
00:20:24,836 --> 00:20:27,496
So a very common question this
year, especially has been,

311
00:20:28,016 --> 00:20:30,796
what did Mark Zuckerberg
take CS50?

312
00:20:30,796 --> 00:20:34,876
We thought we would answer this
authoritatively with Mark's plan

313
00:20:34,876 --> 00:20:37,136
of study, so far as
computer science goes,

314
00:20:37,356 --> 00:20:42,716
before he left this campus
-- though he did not.

315
00:20:42,996 --> 00:20:45,776
So we perhaps should have
mentioned that if your goal

316
00:20:45,776 --> 00:20:49,276
in here at Harvard is to start
the next Facebook.com of sorts,

317
00:20:49,506 --> 00:20:51,926
you really want to
start with CS51.

318
00:20:51,926 --> 00:20:55,936
Moving on to CS121 in theory,
124 in data structures,

319
00:20:55,936 --> 00:20:59,986
161 in operating systems, 182
in artificial intelligence,

320
00:20:59,986 --> 00:21:02,056
and 91R is a research-oriented
course.

321
00:21:02,056 --> 00:21:03,376
But we went back a bit further.

322
00:21:03,626 --> 00:21:05,246
Turns out that another gentleman

323
00:21:05,246 --> 00:21:08,556
who left Harvard a bit early
didn't even take any CS courses.

324
00:21:08,756 --> 00:21:12,466
Admittedly there was no
CS department back then.

325
00:21:12,466 --> 00:21:14,626
These are the applied
math courses that he took,

326
00:21:14,626 --> 00:21:17,536
specifically Professor Harry
Lewis, who you met last week,

327
00:21:17,806 --> 00:21:20,046
who has many fun stories to tell

328
00:21:20,046 --> 00:21:23,126
about Bill Gates'
time here at Harvard.

329
00:21:23,126 --> 00:21:24,946
So there are your
authoritative answers

330
00:21:24,946 --> 00:21:28,736
as to what those folks took,
but now let's focus on you guys.

331
00:21:28,766 --> 00:21:32,916
So for pset 0 recall you
submitted a scratch project.

332
00:21:32,916 --> 00:21:35,316
And just for fun, we
asked among the staff,

333
00:21:35,316 --> 00:21:38,726
which projects did you find
the cutest, the most amazing,

334
00:21:38,726 --> 00:21:41,036
really, and search your
own adjective there.

335
00:21:41,036 --> 00:21:42,906
And we did get a
number of nominations,

336
00:21:42,906 --> 00:21:45,316
a few of which we wanted
to recognize today.

337
00:21:45,546 --> 00:21:49,556
One of the submissions
that we will honor today

338
00:21:49,716 --> 00:21:55,366
as the amazingest award, is
going to go to the author

339
00:21:55,366 --> 00:21:57,976
of this here Scratch Project.

340
00:21:58,516 --> 00:23:18,616
[ Music ]

341
00:23:19,116 --> 00:23:21,486
>> So if the next time you're
at some wedding dancing

342
00:23:21,486 --> 00:23:24,346
to that song, Nicole Bowman
will have done her job.

343
00:23:24,346 --> 00:23:26,086
If Nicole is here and
would like to come up

344
00:23:26,086 --> 00:23:29,056
and receive her Certificate
of Distinction from CS50.

345
00:23:29,236 --> 00:23:29,896
Nicole?

346
00:23:31,516 --> 00:23:38,546
[ Applause ]

347
00:23:39,046 --> 00:23:41,096
>> Congratulations
from the CS50 staff.

348
00:23:41,096 --> 00:23:41,656
>> Thank you.

349
00:23:42,026 --> 00:23:45,316
>> So another project that
we would like to honor

350
00:23:45,316 --> 00:23:49,216
in the category of
cutest is this one here.

351
00:23:49,216 --> 00:23:51,966
This one requires a
little bit of interaction.

352
00:23:51,966 --> 00:23:56,146
Could we have a volunteer
willing to steer this animation?

353
00:23:56,396 --> 00:23:59,926
Anyone staring at me.

354
00:23:59,926 --> 00:24:00,746
Yes? What's your name?

355
00:24:01,376 --> 00:24:01,606
>> Me?

356
00:24:01,606 --> 00:24:03,996
>> Yes. Are you comfortable
coming up?

357
00:24:04,056 --> 00:24:06,506
Travis? All right, come on up.

358
00:24:06,866 --> 00:24:10,176
All right, Travis, we
have here the handiwork

359
00:24:10,176 --> 00:24:11,576
of one of your classmates.

360
00:24:11,846 --> 00:24:15,246
Directions will appear on
the screen in just a moment.

361
00:24:15,966 --> 00:24:17,966
There we go.

362
00:24:18,516 --> 00:24:44,546
[ Music ]

363
00:24:45,046 --> 00:24:47,156
>> Actually I think the
only thing you might have

364
00:24:47,156 --> 00:24:48,506
to do is hit the spacebar.

365
00:24:48,506 --> 00:24:48,956
That's okay.

366
00:24:49,516 --> 00:26:10,586
[ Music ]

367
00:26:11,086 --> 00:26:13,876
>> So congratulations to
Travis and to Sam Singer.

368
00:26:14,176 --> 00:26:18,036
>> Thank you very much.

369
00:26:18,646 --> 00:26:22,956
>> Sam, are you here as well?

370
00:26:23,246 --> 00:26:25,976
Sam? There we go.

371
00:26:26,516 --> 00:26:31,656
[ Applause ]

372
00:26:32,156 --> 00:26:32,976
>> Congratulations.

373
00:26:33,676 --> 00:26:35,036
There you go.

374
00:26:35,036 --> 00:26:40,876
All right, and lastly, we have a
new category, as defined by one

375
00:26:40,876 --> 00:26:41,826
of the teaching fellows.

376
00:26:42,116 --> 00:26:46,906
This one goes in the super
awesome category for 2010.

377
00:26:46,906 --> 00:26:49,966
And I give you this
project here.

378
00:26:50,516 --> 00:28:40,556
[ Music ]

379
00:28:41,056 --> 00:28:45,036
>> So the super award for
2010 goes to Kristin Logan.

380
00:28:45,036 --> 00:28:45,976
Kristin, if you are here.

381
00:28:46,516 --> 00:28:59,106
[ Applause ]

382
00:28:59,606 --> 00:29:00,826
>> Congratulations from CS50.

383
00:29:00,826 --> 00:29:01,126
>> Thank you.

384
00:29:02,586 --> 00:29:06,356
>> All right, just a couple
of more recognitions here.

385
00:29:06,586 --> 00:29:09,846
In problem set 5, recall
that you were challenged

386
00:29:09,846 --> 00:29:13,146
with scouring campus for all
sorts of computer scientists.

387
00:29:13,376 --> 00:29:16,056
A few of you indeed found
a whole lot of them.

388
00:29:16,056 --> 00:29:18,556
We've linked to the galleries
on the course's Web site,

389
00:29:18,556 --> 00:29:22,066
but ultimately the two sections
that submitted both the most

390
00:29:22,066 --> 00:29:25,246
and the most on time
were Matt Chartier

391
00:29:25,296 --> 00:29:27,636
and Yuhki Yamashita's section.

392
00:29:27,636 --> 00:29:29,416
Receiving them on behalf

393
00:29:29,416 --> 00:29:32,396
of those sections here
first will be Joseph,

394
00:29:32,456 --> 00:29:33,766
Paul and Kristin.

395
00:29:33,766 --> 00:29:37,916
If any or all of you three are
here, this is of course Joseph

396
00:29:37,916 --> 00:29:39,866
with Professor Stu Shieber.

397
00:29:40,296 --> 00:29:41,486
Joseph, Paul?

398
00:29:43,016 --> 00:29:45,796
Anyone? Kristin?

399
00:29:45,796 --> 00:29:46,716
Okay.

400
00:29:47,516 --> 00:29:51,596
[ Applause ]

401
00:29:52,096 --> 00:29:52,696
>> Very nicely done.

402
00:29:52,696 --> 00:29:53,586
There we are, all right.

403
00:29:53,886 --> 00:29:56,426
One, and here you go.

404
00:29:57,916 --> 00:30:01,146
And two. And three.

405
00:30:01,656 --> 00:30:02,626
And congratulations.

406
00:30:03,326 --> 00:30:07,326
And CS50 stress balls
is what these are.

407
00:30:07,996 --> 00:30:08,826
All right.

408
00:30:08,826 --> 00:30:11,566
In the other section here,

409
00:30:11,946 --> 00:30:15,686
this fellow pretty
much found almost all

410
00:30:15,686 --> 00:30:18,736
of the computer scientists
on campus single-handedly,

411
00:30:18,736 --> 00:30:22,266
because I don't know what's
with the other students

412
00:30:22,266 --> 00:30:23,376
in this particular section,

413
00:30:23,376 --> 00:30:26,696
but you made poor Zack
introduce himself to every TF,

414
00:30:26,696 --> 00:30:30,346
CA and professor on campus.

415
00:30:30,446 --> 00:30:31,546
But Zack, if you are here

416
00:30:31,546 --> 00:30:35,416
to receive your section
prize, Zack, come on down.

417
00:30:35,776 --> 00:30:37,726
I will say, while he's up here,

418
00:30:38,016 --> 00:30:41,866
we did have to disqualify
a couple of photos,

419
00:30:41,866 --> 00:30:48,916
namely this one was subjected
to some staff analysis.

420
00:30:48,916 --> 00:30:49,936
[ Laughing ]

421
00:30:49,936 --> 00:30:55,056
>> We used the enhanced
feature and then saw quite a bit

422
00:30:55,056 --> 00:30:56,806
of pixilation there
around the edges.

423
00:30:57,426 --> 00:30:59,646
But nonetheless,
congratulations to Zack.

424
00:31:00,056 --> 00:31:02,656
>> Thanks a lot.

425
00:31:03,876 --> 00:31:08,976
>> It is. So just two
such recognitions to go.

426
00:31:08,976 --> 00:31:12,176
So in Pset 6, this being
really the only academic

427
00:31:12,176 --> 00:31:16,296
of these awards here, we had
the big board and the speller

428
00:31:16,296 --> 00:31:19,166
and your fastest implementation
possible of the dictionary.

429
00:31:19,416 --> 00:31:23,416
It turns out that as of last
night, those who ranked the top

430
00:31:23,416 --> 00:31:25,486
of the list were
these 10 folks here,

431
00:31:25,486 --> 00:31:27,216
which is a feat unto itself.

432
00:31:27,576 --> 00:31:31,326
I will say here -- this is the
first time this has happened --

433
00:31:31,646 --> 00:31:33,516
finishers number 1 and 2,

434
00:31:33,516 --> 00:31:36,146
it turns out they're not
actually CS50 students.

435
00:31:36,146 --> 00:31:37,336
We did some investigation.

436
00:31:37,336 --> 00:31:41,696
It turns out these are some
uberzealous undergraduates

437
00:31:41,696 --> 00:31:44,086
who did ask us for Cloud
accounts, and we thought,

438
00:31:44,166 --> 00:31:46,716
go get 'em, let's see what
you can do with the Cloud.

439
00:31:46,906 --> 00:31:47,836
Turns out, they won.

440
00:31:48,016 --> 00:31:49,436
So we're going to go ahead

441
00:31:49,436 --> 00:31:54,646
and recognize instead our
own CS50s, Joseph Rusher.

442
00:31:54,646 --> 00:31:58,726
If Joe, you are here today
to accept 1st place on behalf

443
00:31:58,726 --> 00:32:00,146
of CS50 for the big board.

444
00:32:00,146 --> 00:32:01,826
Joe, come on down.

445
00:32:03,516 --> 00:32:13,636
[ Applause ]

446
00:32:14,136 --> 00:32:16,816
>> So that is still linked
on the course's Web site

447
00:32:16,816 --> 00:32:18,056
if you would like
to play around.

448
00:32:18,056 --> 00:32:19,206
Congratulations, Joe.

449
00:32:19,366 --> 00:32:19,636
>> Thank you.

450
00:32:19,636 --> 00:32:20,386
>> There you are.

451
00:32:20,636 --> 00:32:21,166
All right.

452
00:32:22,926 --> 00:32:26,866
So lest you be feeling
a little disappointed

453
00:32:26,866 --> 00:32:29,786
that you didn't make the top 10,
realize that I didn't, either.

454
00:32:30,086 --> 00:32:32,856
So I clocked in at 153.

455
00:32:32,856 --> 00:32:34,506
So my try wasn't doing so well.

456
00:32:34,506 --> 00:32:39,746
But thankfully, our own CS50
teaching fellow Ken Parreno set

457
00:32:39,746 --> 00:32:44,676
a nice Omega bound for us all
here in 353, using a total

458
00:32:44,676 --> 00:32:49,246
of 5,661 seconds to
implement his dictionary.

459
00:32:49,246 --> 00:32:53,716
So congrats to anyone
above Ken this semester.

460
00:32:54,986 --> 00:32:58,976
In problem set 7, we
had one last big board.

461
00:32:59,386 --> 00:33:03,096
This one, too, we realized
there are some opportunities

462
00:33:03,096 --> 00:33:05,896
for exploitation when
it comes to trading

463
00:33:05,896 --> 00:33:07,436
or simulating trades thereof.

464
00:33:07,436 --> 00:33:10,996
This is how the big
board looked at the close

465
00:33:11,316 --> 00:33:13,156
of markets this past week.

466
00:33:13,586 --> 00:33:21,096
Michael Shen, with $30 billion,
completely trouncing Zack.

467
00:33:21,256 --> 00:33:23,076
I mean, we're not even
going to give a 2nd place,

468
00:33:23,076 --> 00:33:26,996
given that there's an additional
comma in Michael's there.

469
00:33:27,206 --> 00:33:29,366
Michael, you may
recall from quiz 1,

470
00:33:29,366 --> 00:33:31,386
as having user name dshen.

471
00:33:31,646 --> 00:33:33,136
So Michael, if you are here,

472
00:33:33,136 --> 00:33:35,616
we have a little
certificate for you as well.

473
00:33:35,616 --> 00:33:37,976
Michael? There he is.

474
00:33:38,516 --> 00:33:45,546
[ Applause ]

475
00:33:46,046 --> 00:33:47,156
>> Very well done.

476
00:33:48,416 --> 00:33:51,016
I should share one
anecdote, which is I think,

477
00:33:51,296 --> 00:33:52,886
because of a bug in the --

478
00:33:52,886 --> 00:33:55,786
because of a bug
or lack of feature

479
00:33:55,786 --> 00:33:57,966
in the staff's implementation
of CS50 Finance,

480
00:33:58,166 --> 00:34:01,606
we made the poor design decision
of only using a 32-bit integer,

481
00:34:01,806 --> 00:34:05,106
the result of which is that
I received a very nice note

482
00:34:05,106 --> 00:34:07,166
from Michael asking for a refund

483
00:34:07,166 --> 00:34:11,276
of the $20 million my
floating point error cost him.

484
00:34:11,566 --> 00:34:14,216
So we did add that back
to his cash balance.

485
00:34:14,776 --> 00:34:20,056
Congratulations.

486
00:34:20,056 --> 00:34:20,366
[ Applause ]

487
00:34:20,366 --> 00:34:20,916
>> All right.

488
00:34:21,586 --> 00:34:23,396
So how did we actually get here?

489
00:34:23,466 --> 00:34:27,596
Recall that just 12 or so
weeks ago, this is what most

490
00:34:27,596 --> 00:34:29,496
of you were writing for
the very first time.

491
00:34:29,496 --> 00:34:31,536
70 percent of you
in this class claim

492
00:34:31,536 --> 00:34:33,966
to have never programmed
before, and we started

493
00:34:34,006 --> 00:34:36,446
with certainly something
relatively simple,

494
00:34:36,446 --> 00:34:38,136
something relatively
fun scratch.

495
00:34:38,356 --> 00:34:40,866
But if you now think back to
the week after that and the week

496
00:34:40,866 --> 00:34:43,486
after that, realize the
trajectory that you've been

497
00:34:43,486 --> 00:34:44,846
on all these many weeks.

498
00:34:44,986 --> 00:34:47,796
This was hard in week
1 of this course.

499
00:34:47,796 --> 00:34:49,576
You may recall having
various bugs,

500
00:34:49,576 --> 00:34:51,906
having trouble getting the
pound signs to print and such.

501
00:34:52,156 --> 00:34:54,326
And this was problem set
1 where you simply had

502
00:34:54,326 --> 00:34:57,616
to print some ASCII R, which if
you now look back at your code,

503
00:34:57,616 --> 00:35:00,056
it's probably longer than
the program needs to be,

504
00:35:00,056 --> 00:35:02,066
now that you have some
better programming chops.

505
00:35:02,296 --> 00:35:06,286
But it was also the first
of several challenges.

506
00:35:06,286 --> 00:35:08,916
And if you haven't already,
do take a moment to look back,

507
00:35:08,916 --> 00:35:11,946
even to grimace just a little
bit, at the work you first did

508
00:35:11,946 --> 00:35:13,516
in the course, because really,

509
00:35:13,516 --> 00:35:16,176
this is when we were only
using four loops, while loops,

510
00:35:16,466 --> 00:35:17,596
variables, and the like.

511
00:35:17,596 --> 00:35:18,876
And the week after
that, granted,

512
00:35:18,876 --> 00:35:21,586
we did introduce a sexier
domain, that of cryptography,

513
00:35:21,756 --> 00:35:24,126
but at the end of the day the
program you submitted still did

514
00:35:24,126 --> 00:35:26,656
something relatively simple,
still a blinking cursor,

515
00:35:26,886 --> 00:35:28,376
typing in text at the prompt,

516
00:35:28,506 --> 00:35:31,276
and then getting back some
plain text or cipher text

517
00:35:31,276 --> 00:35:33,216
with our Caesar and
visionair ciphers.

518
00:35:33,416 --> 00:35:36,756
One week after that we finally
started moving into the realm

519
00:35:37,046 --> 00:35:40,006
of modernity and games, and
yet we still were limited

520
00:35:40,006 --> 00:35:41,796
by ASCII art, of sorts.

521
00:35:41,796 --> 00:35:43,646
This of course, was
the game of 15,

522
00:35:43,826 --> 00:35:47,106
but with problem set 4 did
we introduce a library,

523
00:35:47,106 --> 00:35:48,626
the first of several libraries.

524
00:35:49,056 --> 00:35:51,406
Namely this one was ncurses.

525
00:35:51,406 --> 00:35:52,996
And even though you
still had to interact

526
00:35:52,996 --> 00:35:55,226
with your programs using
but a keyboard and no mouse,

527
00:35:55,526 --> 00:35:58,546
at least now you were starting
to find yourself perhaps

528
00:35:58,546 --> 00:36:02,276
in a domain, in a user interface
a bit more familiar to you.

529
00:36:02,496 --> 00:36:04,776
Fast forward one week
later and you discovered

530
00:36:04,776 --> 00:36:07,466
that it was indeed
Professor Plum in the lounge

531
00:36:07,466 --> 00:36:10,376
with the candlestick, and
this is very much a real-world

532
00:36:10,376 --> 00:36:12,836
problem, that of
forensics and data recovery.

533
00:36:13,096 --> 00:36:15,646
The jpegs you recall
were another part

534
00:36:15,646 --> 00:36:17,606
of that piece set,
and thereafter.

535
00:36:17,606 --> 00:36:19,356
And this one should
give you a bit of pause,

536
00:36:20,006 --> 00:36:23,146
especially if things
like this were difficult

537
00:36:23,146 --> 00:36:24,216
at the start of the semester.

538
00:36:24,216 --> 00:36:25,776
Realize that by problem set 6,

539
00:36:26,086 --> 00:36:29,016
you were implementing fairly
sophisticated data structures

540
00:36:29,016 --> 00:36:31,946
and memory that are very easy
to draw on the screen like this,

541
00:36:32,236 --> 00:36:35,526
but consider how difficult it
probably was wiring these data

542
00:36:35,526 --> 00:36:37,786
structures together, getting
all these pointers right,

543
00:36:37,916 --> 00:36:40,666
cashing down all of those memory
related bugs with bal grids,

544
00:36:40,666 --> 00:36:43,566
whether you did a hashtable
like this or a tri like this.

545
00:36:43,646 --> 00:36:45,976
But certainly even if you
didn't make the big board,

546
00:36:45,976 --> 00:36:48,586
the fact that you were finally
wiring something like this

547
00:36:48,586 --> 00:36:51,796
up in memory, using just
numbers at the end of the day

548
00:36:51,796 --> 00:36:53,266
in the most simple
of instructions,

549
00:36:53,446 --> 00:36:56,186
is really testament to
just how far you've come

550
00:36:56,486 --> 00:36:57,636
over these several weeks.

551
00:36:57,636 --> 00:37:00,956
And then, simply so that we
actually end the semester

552
00:37:01,226 --> 00:37:03,316
demonstrating that
you've not learned C;

553
00:37:03,316 --> 00:37:05,886
you've learned computer science
and you've learned programming,

554
00:37:06,136 --> 00:37:09,126
we introduce of course, PHP
and a little bit of HTML, CSS,

555
00:37:09,126 --> 00:37:12,646
JavaScript and SQL,
and finally do interact

556
00:37:12,646 --> 00:37:15,656
with a more familiar
mechanism, namely a browser.

557
00:37:15,656 --> 00:37:18,776
Finally are you able to
go in the 8th problem set

558
00:37:19,076 --> 00:37:22,086
to implementing, my God, a
three-dimensional video game

559
00:37:22,086 --> 00:37:24,396
of your very own
campus, including some

560
00:37:24,396 --> 00:37:26,086
of your very own friends.

561
00:37:26,086 --> 00:37:29,956
And again, think back to where
we began, which was here.

562
00:37:30,016 --> 00:37:33,636
And that is in fact just over
12 weeks' time, all the result

563
00:37:33,806 --> 00:37:35,406
of what you put into
this course.

564
00:37:35,406 --> 00:37:36,816
To give you a sense, in fact,

565
00:37:37,026 --> 00:37:40,936
of just how much this latter
context, that of the web, HTML,

566
00:37:40,996 --> 00:37:44,126
SQL, JavaScript and like
resonates, here is a chart

567
00:37:44,126 --> 00:37:46,386
that depicts exactly what kinds

568
00:37:46,386 --> 00:37:49,876
of projects most students have
declared themselves as tackling

569
00:37:49,956 --> 00:37:52,276
for this year's final projects.

570
00:37:52,566 --> 00:37:55,136
Website is up there at the
top, Tool, which is sort

571
00:37:55,136 --> 00:37:57,236
of an all-encompassing
generic term we use,

572
00:37:57,236 --> 00:38:00,596
IOS for the Apple
platform, SMS, Facebook.

573
00:38:00,926 --> 00:38:03,166
Now, I'm being a little
disingenuous here,

574
00:38:03,166 --> 00:38:05,536
so you'll recall perhaps
that Brian Kernahan a couple

575
00:38:05,536 --> 00:38:09,356
of weeks ago cautioned
against lying with statistics.

576
00:38:09,356 --> 00:38:11,236
In fact, I kind of am,

577
00:38:11,236 --> 00:38:13,796
given that I'm using what's
called a logarithmic scale.

578
00:38:13,796 --> 00:38:17,706
Using base 10 on the axis there,
if we really present this data

579
00:38:17,706 --> 00:38:21,996
as a computer scientist
should, you'll see that web,

580
00:38:22,666 --> 00:38:25,666
this world wide web is
perhaps here to stay.

581
00:38:25,976 --> 00:38:28,446
A supermajority of
you, up from 60 percent

582
00:38:28,446 --> 00:38:30,596
to 80 some odd percent
this semester,

583
00:38:30,766 --> 00:38:32,756
are tackling web-based
final projects.

584
00:38:32,756 --> 00:38:34,736
But this, too, is really
testament to the fact,

585
00:38:34,916 --> 00:38:37,106
especially when you have to
respond to friend's questions

586
00:38:37,106 --> 00:38:38,326
as to, what did you learn?

587
00:38:38,326 --> 00:38:39,436
What languages did you learn?

588
00:38:39,686 --> 00:38:41,736
It's sort of an immaterial
question.

589
00:38:41,736 --> 00:38:44,276
It ultimately is about
the ideas and the fact

590
00:38:44,276 --> 00:38:47,446
that we spent 75 percent
of the semester in C

591
00:38:47,446 --> 00:38:50,036
so that you have a foundation
now on which to build

592
00:38:50,036 --> 00:38:52,676
with any language in
this class or beyond.

593
00:38:52,676 --> 00:38:54,106
In fact, the languages
being used

594
00:38:54,106 --> 00:38:56,626
for projects certainly involve
some of those web-based ones,

595
00:38:56,826 --> 00:38:59,816
but there are folks using C,
a language called Ruby, Java,

596
00:38:59,816 --> 00:39:02,526
Objective C, Python,
Actionscript, C plus plus

597
00:39:02,856 --> 00:39:04,416
and a few more down below.

598
00:39:04,416 --> 00:39:07,016
So you will see certainly
come to CS50 Fair,

599
00:39:07,186 --> 00:39:08,886
what all of your
classmates have done,

600
00:39:09,146 --> 00:39:11,156
especially if it's not
a world familiar to you.

601
00:39:11,156 --> 00:39:14,026
Now, with that said, some of you
might have seen this in section,

602
00:39:14,276 --> 00:39:16,666
but you can take things too far.

603
00:39:16,666 --> 00:39:19,406
You can take your
enthusiasm too far.

604
00:39:19,586 --> 00:39:20,336
Don't do this.

605
00:39:23,656 --> 00:39:25,296
Okay, I wasn't sure
that would go over,

606
00:39:25,296 --> 00:39:26,926
a little chuckle, interesting.

607
00:39:27,086 --> 00:39:31,936
So the talking point
here for this slide is,

608
00:39:31,936 --> 00:39:34,546
my note to myself is,
we will share proposals

609
00:39:34,546 --> 00:39:35,776
on the course's Web site.

610
00:39:35,776 --> 00:39:37,326
This was my visual
cue to say that.

611
00:39:37,526 --> 00:39:38,726
So no, in all fairness,

612
00:39:38,726 --> 00:39:41,026
given that there are
400-plus projects,

613
00:39:41,026 --> 00:39:44,086
many of them being implemented
by individuals, some by groups,

614
00:39:44,306 --> 00:39:47,106
we will post if you have
opted in by your proposal,

615
00:39:47,216 --> 00:39:49,026
all of those proposals
online just

616
00:39:49,026 --> 00:39:50,446
so that you can get
a sneak teaser

617
00:39:50,446 --> 00:39:52,146
of what your classmates
are going to be working

618
00:39:52,146 --> 00:39:53,396
on over the next
couple of weeks.

619
00:39:53,436 --> 00:39:57,896
For the first ever CS50
hackathon, we will be heading

620
00:39:57,896 --> 00:39:59,756
down the street to Microsoft.

621
00:39:59,756 --> 00:40:01,506
Some of you who tuned
into Office Space

622
00:40:01,506 --> 00:40:04,646
with us might recall that they
have a beautiful space there,

623
00:40:04,646 --> 00:40:05,586
very high tech.

624
00:40:05,656 --> 00:40:07,876
Frankly, there's a lot of
Xboxes, ping-pong table,

625
00:40:08,076 --> 00:40:10,806
way more toys than we have
here in our own building.

626
00:40:10,806 --> 00:40:14,256
So they have a capacity of
up to 240, which is good,

627
00:40:14,256 --> 00:40:19,106
because on Thursday,
12/2, that is the last day

628
00:40:19,106 --> 00:40:22,056
of classes overflowing to the
first day of reading period.

629
00:40:22,056 --> 00:40:23,896
The plan is to be
there around 8 p.m.

630
00:40:24,096 --> 00:40:28,456
to 6 a.m. Food will be served
multiple times, and the plan is

631
00:40:28,456 --> 00:40:30,676
to offer you a chance to
really dive in by yourself

632
00:40:30,676 --> 00:40:32,746
or with your friends
to your final project.

633
00:40:32,746 --> 00:40:34,246
Essentially what
we'll do at the start

634
00:40:34,246 --> 00:40:36,726
of the evening is challenge
you to decide for yourself

635
00:40:37,046 --> 00:40:40,916
by 6 a.m. what would be
a good point to be at,

636
00:40:40,916 --> 00:40:42,816
what would be a better
point to be at,

637
00:40:42,816 --> 00:40:44,906
and what would be the
best point to be at.

638
00:40:45,196 --> 00:40:47,836
Frankly, if my own experience
and your own experience

639
00:40:47,836 --> 00:40:49,196
in the course is any indication,

640
00:40:49,496 --> 00:40:52,156
it's rare that you ever
actually accomplish as much

641
00:40:52,156 --> 00:40:53,656
as you want in the allowed time.

642
00:40:53,826 --> 00:40:56,716
So we're all really going to
shoot for at least exiting

643
00:40:56,716 --> 00:40:58,576
that morning, stumbling home

644
00:40:58,576 --> 00:41:00,456
with having accomplished
something good.

645
00:41:00,456 --> 00:41:04,336
But you'll still have a week
after that to continue your work

646
00:41:04,556 --> 00:41:07,466
on the TFs and CAs and I will
be there in attendance with you.

647
00:41:07,596 --> 00:41:09,976
And then, of course, the
CS50 Fair, a word on this.

648
00:41:10,056 --> 00:41:13,726
So the CS50 Fair, if you haven't
been, is a large exhibition

649
00:41:13,726 --> 00:41:16,556
across the streets at
Northwest Science Labs.

650
00:41:16,556 --> 00:41:19,126
It will be adorned with plenty
of food and music and balloons.

651
00:41:19,326 --> 00:41:22,356
Essentially we'll divide the
afternoon into three shifts.

652
00:41:22,356 --> 00:41:23,496
You'll find out in a week

653
00:41:23,496 --> 00:41:26,396
or two's time what shift
you're in, 1, 2 or 3.

654
00:41:26,536 --> 00:41:29,286
You'll bring your laptops,
you'll set up shop according

655
00:41:29,286 --> 00:41:31,506
to the instructions you'll
receive, and then exhibits,

656
00:41:31,506 --> 00:41:33,466
your final projects, the
people standing around you,

657
00:41:33,466 --> 00:41:34,606
your friends who
have drooped by,

658
00:41:34,606 --> 00:41:35,836
to other folks in attendance.

659
00:41:36,126 --> 00:41:41,016
Last year's was attended by
1,000-plus individuals in total.

660
00:41:41,016 --> 00:41:43,966
This year, and as well as
your classmates will we have

661
00:41:43,966 --> 00:41:46,856
recruiters from Google,
Facebook, Microsoft, Apple,

662
00:41:46,856 --> 00:41:50,206
Amazon, Disney there
to just chat you up,

663
00:41:50,316 --> 00:41:51,956
see if you're interested
in internships,

664
00:41:51,956 --> 00:41:53,626
see if you're interested
in free stuff

665
00:41:53,626 --> 00:41:55,346
that they have there
or full-time jobs.

666
00:41:55,566 --> 00:41:59,266
Also in attendance this year
will be President Drew Foust,

667
00:41:59,316 --> 00:42:01,676
Dean Mike Smith,
Dean Sherry Murray

668
00:42:01,676 --> 00:42:02,636
and a whole bunch of others.

669
00:42:02,636 --> 00:42:05,066
So not to freak you
out, it really is meant

670
00:42:05,066 --> 00:42:07,706
to be a very casual
opportunity and a chance to sort

671
00:42:07,706 --> 00:42:09,806
of take pride in what
you've accomplished,

672
00:42:10,036 --> 00:42:15,596
but it's also meant to be really
the true climax of the semester.

673
00:42:15,596 --> 00:42:18,016
And that said, to
incentivize your friends

674
00:42:18,016 --> 00:42:19,926
to actually come see
your projects out of more

675
00:42:19,926 --> 00:42:22,456
than just love for you,
there will be a raffle

676
00:42:22,456 --> 00:42:25,086
with amazing prizes, which
will include such things

677
00:42:25,086 --> 00:42:28,606
as last year's Xbox,
Wii, Playstation,

678
00:42:28,816 --> 00:42:29,896
those kinds of things.

679
00:42:29,896 --> 00:42:31,856
So we will -- if
your text messages

680
00:42:31,856 --> 00:42:34,496
to them is not enough,
the prizes will be.

681
00:42:34,876 --> 00:42:40,536
So now we have an opportunity
for one last interaction.

682
00:42:40,786 --> 00:42:43,856
For this we need at least three
volunteers from the staff,

683
00:42:44,176 --> 00:42:46,546
three prefabricated volunteers

684
00:42:46,546 --> 00:42:47,926
from the staff, want
to come on up?

685
00:42:48,446 --> 00:42:50,286
But we'll need two teams as well

686
00:42:50,286 --> 00:42:51,916
from among the student
audiences.

687
00:42:51,916 --> 00:42:53,436
Marta seems to be volunteering.

688
00:42:54,036 --> 00:42:55,936
We need -- yes, you two.

689
00:42:55,936 --> 00:42:58,716
Oh, now you want to participate.

690
00:42:58,716 --> 00:42:59,586
All right.

691
00:42:59,586 --> 00:43:01,556
How about you two here, three,

692
00:43:01,856 --> 00:43:05,496
and your friend is nominating
you for six in total, I think.

693
00:43:05,496 --> 00:43:05,996
Come on up.

694
00:43:06,276 --> 00:43:09,056
We'll divide you into two teams.

695
00:43:09,146 --> 00:43:10,766
Friends' nominations
are binding.

696
00:43:12,476 --> 00:43:13,146
So come on up.

697
00:43:13,146 --> 00:43:14,836
Hopefully we have
enough seats here.

698
00:43:14,966 --> 00:43:22,306
We need a head teaching
fellow to run the scoreboard.

699
00:43:23,176 --> 00:43:26,106
Cansu Aydede, very willingly.

700
00:43:26,476 --> 00:43:26,936
All right.

701
00:43:27,376 --> 00:43:32,536
And what is this advanced
preparation going on?

702
00:43:32,666 --> 00:43:36,536
Okay, so we're going to have
a little three-team thing here

703
00:43:36,536 --> 00:43:38,936
and like two few
chairs, it seems.

704
00:43:38,936 --> 00:43:39,736
We'll figure that out.

705
00:43:39,906 --> 00:43:41,466
So let's put the
teaching fellows and staff

706
00:43:41,586 --> 00:43:42,816
over here if you could.

707
00:43:43,056 --> 00:43:44,866
Do we need an extra
chair or two?

708
00:43:45,656 --> 00:43:46,486
Yep, okay.

709
00:43:48,396 --> 00:43:51,556
Here's one, need one more.

710
00:43:52,346 --> 00:43:53,166
Still one.

711
00:43:54,116 --> 00:43:55,666
It's like musical chairs.

712
00:43:55,666 --> 00:43:57,416
All right, one of you
gets the piano bench.

713
00:43:57,646 --> 00:44:00,856
>> There are chairs here.

714
00:44:01,026 --> 00:44:01,876
>> Even better, even better.

715
00:44:02,196 --> 00:44:05,616
All right, so I'm going to go
ahead and queue up the screen.

716
00:44:05,616 --> 00:44:09,456
This is a little tradition
we have here in CS50.

717
00:44:10,866 --> 00:44:14,146
We kind of make up some rules
as we go -- fair notice.

718
00:44:14,676 --> 00:44:19,286
But we made a little Web site
using our HTML skills here.

719
00:44:19,606 --> 00:44:22,066
Namely I'm going
to go to CS50.net.

720
00:44:23,806 --> 00:44:25,196
All right.

721
00:44:26,046 --> 00:44:29,126
So now, if I have this
set, let's try this.

722
00:44:29,906 --> 00:44:31,886
>> This is Jeopardy.

723
00:44:34,196 --> 00:44:35,246
>> All right, very good.

724
00:44:35,246 --> 00:44:38,896
>> And now, here is
the host of Jeopardy.

725
00:44:39,896 --> 00:44:40,776
>> Okay, that'll be me.

726
00:44:41,106 --> 00:44:43,966
And here we go into
Single Jeopardy.

727
00:44:43,966 --> 00:44:48,656
So the way this is going to
work is kind of like Jeopardy,

728
00:44:48,726 --> 00:44:50,896
but again, we're going to
make some things up as we go.

729
00:44:50,896 --> 00:44:53,336
We'll have a few rounds
of questions and then --

730
00:44:54,196 --> 00:44:55,746
oh, I guess we have two
big teams this year?

731
00:44:55,806 --> 00:44:56,296
That's fine.

732
00:44:57,346 --> 00:44:59,296
Shall we do that?

733
00:44:59,296 --> 00:45:01,396
Okay, so these four staff

734
00:45:01,396 --> 00:45:04,676
against these 2,
4, 6, 7 students.

735
00:45:04,956 --> 00:45:05,716
No, that's good.

736
00:45:06,566 --> 00:45:07,016
That's good.

737
00:45:07,336 --> 00:45:10,846
So, and Yuhki and Cansu are
going to be the arbiters here

738
00:45:10,846 --> 00:45:12,566
as to whose hand goes up first.

739
00:45:12,566 --> 00:45:14,856
We only have time for a few
questions in each round,

740
00:45:14,856 --> 00:45:16,086
because we do want
to get to cake.

741
00:45:16,316 --> 00:45:19,326
But here we have in the
coin toss beforehand,

742
00:45:19,326 --> 00:45:21,286
the students won the toss,
which means students,

743
00:45:21,636 --> 00:45:23,726
somehow if you don't yet
have a leader you're going

744
00:45:23,726 --> 00:45:25,226
to need someone to
take direction here,

745
00:45:25,516 --> 00:45:27,976
take the lead here
and pick a category.

746
00:45:28,676 --> 00:45:31,686
>> We'll be on week
2 for a thousand.

747
00:45:31,686 --> 00:45:33,346
>> Week 2 for one thousand.

748
00:45:33,346 --> 00:45:33,986
Now, let's -- do you--

749
00:45:33,986 --> 00:45:35,356
>> Week 2.

750
00:45:35,806 --> 00:45:37,166
>> Week 2 for one thousand.

751
00:45:37,166 --> 00:45:39,516
So lest you all be
feeling left out, realize,

752
00:45:39,816 --> 00:45:41,256
these are your questions.

753
00:45:41,256 --> 00:45:44,116
So those quiz review
questions Yuhki asked you for,

754
00:45:44,766 --> 00:45:46,676
as you may have noticed,
they really make the quiz.

755
00:45:46,676 --> 00:45:48,126
Because a lot of these
questions are like,

756
00:45:48,126 --> 00:45:50,746
what's 3 in binary,
what's 4 in binary.

757
00:45:51,176 --> 00:45:55,186
So we read some of our own, but
we did bring these here today.

758
00:45:55,186 --> 00:45:57,296
So I have here some
week 2 questions.

759
00:45:57,296 --> 00:45:58,956
And when you answer,
just be sure to speak

760
00:45:58,956 --> 00:46:02,266
into the nearest microphone,
for those playing along at home.

761
00:46:02,266 --> 00:46:06,116
So week 2 for one thousand,
your question is going to be --

762
00:46:06,116 --> 00:46:08,826
and again, raise your hand
to be called on first.

763
00:46:09,116 --> 00:46:12,946
The question is what will happen

764
00:46:12,946 --> 00:46:15,636
if you access memory
outside of your array?

765
00:46:15,876 --> 00:46:16,776
>> We got it.

766
00:46:17,196 --> 00:46:23,996
>> It's not in how
many hands to up.

767
00:46:24,056 --> 00:46:26,536
Oh, the staff?

768
00:46:27,076 --> 00:46:28,696
The staff has control.

769
00:46:28,696 --> 00:46:29,026
Marta?

770
00:46:29,736 --> 00:46:30,696
>> You will get a seg fault.

771
00:46:31,056 --> 00:46:32,686
>> You will in fact
get a seg fault.

772
00:46:32,686 --> 00:46:34,106
For $1,000.

773
00:46:34,746 --> 00:46:35,376
All right.

774
00:46:37,956 --> 00:46:39,726
Staff are in control here.

775
00:46:39,726 --> 00:46:41,026
What category would you like?

776
00:46:45,896 --> 00:46:47,036
>> Week 2 for 800.

777
00:46:47,496 --> 00:46:49,546
>> Week 2 for 800.

778
00:46:49,546 --> 00:46:54,866
Your question from our
students here is going to be,

779
00:46:54,866 --> 00:47:00,996
your question is going to be --
they're all like, what is scope?

780
00:47:01,116 --> 00:47:08,196
What is a global variable?

781
00:47:08,196 --> 00:47:10,246
What's a local variable?

782
00:47:10,386 --> 00:47:15,026
Okay. How about, where
does malloc store data?

783
00:47:16,166 --> 00:47:17,026
Students?

784
00:47:18,576 --> 00:47:19,706
>> On the heap.

785
00:47:19,706 --> 00:47:21,596
>> That is correct for $800.

786
00:47:26,356 --> 00:47:28,196
All right, students
you have control.

787
00:47:28,456 --> 00:47:29,906
>> Week 4 for a thousand.

788
00:47:29,906 --> 00:47:32,096
>> Week 4 for one thousand.

789
00:47:32,096 --> 00:47:38,976
Your question from week
4 is going to be, what

790
00:47:39,516 --> 00:47:46,076
[ Background noise ]

791
00:47:46,576 --> 00:47:49,486
>> Okay. What are the
consequences of a call to malloc

792
00:47:49,486 --> 00:47:51,496
without a later call to free?

793
00:47:52,836 --> 00:47:53,276
Students?

794
00:47:53,276 --> 00:47:55,726
>> What is memory leak?

795
00:47:55,726 --> 00:48:00,516
>> That is true, though this
student put you will leak

796
00:48:00,626 --> 00:48:02,466
memory, in quotes
for some reason.

797
00:48:02,466 --> 00:48:05,116
So but that is correct
for 1,000 in week 4.

798
00:48:05,486 --> 00:48:06,146
Very well done.

799
00:48:06,146 --> 00:48:09,616
All right, what would
you like next?

800
00:48:10,516 --> 00:48:11,986
>> 1,000 week 3.

801
00:48:11,986 --> 00:48:12,406
>> What's that?

802
00:48:12,556 --> 00:48:13,526
>> Week 3 for 1,000.

803
00:48:13,526 --> 00:48:15,646
>> Week 3 for 1,000.

804
00:48:15,646 --> 00:48:20,226
So in week 3, your
question is going to be

805
00:48:21,586 --> 00:48:26,126
which sort is fastest?

806
00:48:26,126 --> 00:48:29,526
Marta? Wait, wait --
oh, it was students.

807
00:48:29,526 --> 00:48:29,976
Students?

808
00:48:30,516 --> 00:48:36,936
[ Laughing ]

809
00:48:37,436 --> 00:48:37,966
>> Heap sort?

810
00:48:37,966 --> 00:48:40,436
>> I quote, "selection
sort I think."

811
00:48:40,986 --> 00:48:48,246
I'm sorry, that --
it's selection sort,

812
00:48:48,246 --> 00:48:49,316
according to the answer key.

813
00:48:49,316 --> 00:48:50,956
So negative 1,000 for students.

814
00:48:50,956 --> 00:48:51,166
>> Oh, no, really?

815
00:48:51,166 --> 00:48:56,726
>> Yes, that's how
Jeopardy works.

816
00:48:56,856 --> 00:48:58,596
All right.

817
00:49:00,386 --> 00:49:03,396
So staff has taken
the lead by 200.

818
00:49:03,696 --> 00:49:05,756
Students though,
you're still in control.

819
00:49:05,936 --> 00:49:09,276
>> Week 0 for 1,000.

820
00:49:09,276 --> 00:49:09,716
>> All right.

821
00:49:09,716 --> 00:49:11,276
We have time for one
or two more questions

822
00:49:11,276 --> 00:49:12,696
in Single Jeopardy here.

823
00:49:13,126 --> 00:49:16,106
Week 0 for 1,000.

824
00:49:16,106 --> 00:49:18,886
Week 0 for 1,000.

825
00:49:18,886 --> 00:49:25,546
And your question is going
to be, your question is going

826
00:49:25,546 --> 00:49:29,666
to be, what does the work
algorithm mean to you?

827
00:49:29,666 --> 00:49:30,366
Students?

828
00:49:30,446 --> 00:49:37,176
>> An algorithm is a way
of solving a problem.

829
00:49:37,696 --> 00:49:39,946
>> That's actually pretty
close, an algorithm is a process

830
00:49:39,946 --> 00:49:41,436
which you can use
to solve a problem.

831
00:49:41,436 --> 00:49:41,976
We'll give it to them.

832
00:49:42,516 --> 00:49:45,626
[ Applause ]

833
00:49:46,126 --> 00:49:48,286
>> All right, last
question in Single Jeopardy.

834
00:49:48,286 --> 00:49:49,976
Students, you're still in
control and in the lead.

835
00:49:50,516 --> 00:49:55,656
[ Background noise ]

836
00:49:56,156 --> 00:50:00,706
>> You know, I'm doing this
randomly, so you could, too.

837
00:50:01,126 --> 00:50:01,366
Week

838
00:50:01,876 --> 00:50:06,016
>> Week 1 for 1,000.

839
00:50:06,546 --> 00:50:08,996
>> Week 1 for 1,000
is what I heard.

840
00:50:08,996 --> 00:50:12,076
All right, so Week 1 for
1,000, your question,

841
00:50:12,076 --> 00:50:17,026
the last in Single Jeopardy
here, is going to be --

842
00:50:17,966 --> 00:50:25,406
What is the standard
compiler used by C?

843
00:50:25,406 --> 00:50:25,496
>> GDB.

844
00:50:26,016 --> 00:50:26,086
>> GC

845
00:50:28,336 --> 00:50:28,426
>> GCC.

846
00:50:28,426 --> 00:50:36,036
>> Oh, oh, students minus 1,000
because he said GDB first.

847
00:50:36,036 --> 00:50:41,996
And my team takes
the lead again.

848
00:50:42,106 --> 00:50:42,956
All right.

849
00:50:43,136 --> 00:50:50,016
You can play that back again
and again on the video.

850
00:50:50,266 --> 00:50:52,626
All right, now we're
in Double Jeopardy,

851
00:50:52,626 --> 00:50:54,776
time for just a few
questions here.

852
00:50:54,996 --> 00:50:57,976
The weeks have changed
from 5 through Rand.

853
00:50:58,526 --> 00:50:59,366
What would you like?

854
00:51:00,006 --> 00:51:00,976
>> Rand for 2,000.

855
00:51:00,976 --> 00:51:02,106
>>? Rand for 2,000.

856
00:51:02,106 --> 00:51:05,256
>> Rand for $2,000,
trying to pull ahead.

857
00:51:05,256 --> 00:51:07,486
And your question is
going to be what is GDB?

858
00:51:07,486 --> 00:51:07,696
Marta?

859
00:51:07,696 --> 00:51:16,266
>> GDB is a debugger
and not a compiler.

860
00:51:16,306 --> 00:51:23,436
>> That is correct for $2,000.

861
00:51:23,436 --> 00:51:25,886
Oh, that did not go over well.

862
00:51:25,886 --> 00:51:27,906
Staff, you're in control.

863
00:51:27,906 --> 00:51:29,496
Time for two more questions.

864
00:51:30,556 --> 00:51:33,736
>> Week 7 2,000.

865
00:51:34,746 --> 00:51:37,636
>> Week 7 for $2,000.

866
00:51:37,636 --> 00:51:42,436
And your question from
week 7 is going to be,

867
00:51:42,896 --> 00:51:48,416
your question is going
to be, what, what,

868
00:51:48,956 --> 00:51:53,026
what is one advantage of a
link list compared to an array?

869
00:51:53,436 --> 00:51:53,716
Marta?

870
00:51:56,606 --> 00:51:59,936
>> You can add elements
easier and faster.

871
00:52:00,016 --> 00:52:00,826
>> That is correct.

872
00:52:00,826 --> 00:52:02,656
A link list allows
for easier insertion

873
00:52:02,656 --> 00:52:05,246
into the list, for $2,000.

874
00:52:05,616 --> 00:52:09,626
All right, so that's
5,000 to 800.

875
00:52:10,426 --> 00:52:13,546
So let's go with
the $2,000 question.

876
00:52:14,976 --> 00:52:18,036
How about week 9 for 2,000.

877
00:52:18,036 --> 00:52:21,966
And let me know, we have like
7 to 10 pages of questions

878
00:52:21,966 --> 00:52:24,686
for every week, except
week 9, where you all kind

879
00:52:24,686 --> 00:52:25,646
of petered out, it seems.

880
00:52:26,086 --> 00:52:30,186
So week 9, your question
for $2,000 and the last here

881
00:52:30,186 --> 00:52:33,196
in Double Jeopardy before we
finish with Final Jeopardy,

882
00:52:33,476 --> 00:52:40,906
is going to be, what
does -- students?

883
00:52:41,516 --> 00:52:49,646
[ Background noise ]

884
00:52:50,146 --> 00:52:50,976
>> What is your answers?

885
00:52:50,976 --> 00:52:53,296
>> Hypertext infrastructure.

886
00:52:53,706 --> 00:52:54,136
>> What?

887
00:52:54,136 --> 00:52:54,986
>> What? Whoa.

888
00:52:56,226 --> 00:52:57,096
Try again, keep trying.

889
00:52:57,816 --> 00:52:59,216
>> Hypertext transfer protocol.

890
00:52:59,356 --> 00:53:00,966
>> That's actually the
answer of the question.

891
00:53:01,516 --> 00:53:08,996
[ Applause ]

892
00:53:09,496 --> 00:53:12,976
>> The question was indeed,
what does http stand for?

893
00:53:13,336 --> 00:53:16,956
So now we have a piece
of paper for you each.

894
00:53:16,956 --> 00:53:18,516
Hopefully one of you has a pen.

895
00:53:18,936 --> 00:53:20,956
Staff can wager up to 5,000.

896
00:53:20,956 --> 00:53:23,936
Students can wager up to 2800.

897
00:53:24,166 --> 00:53:26,376
So you do have a
fighting chance here.

898
00:53:26,736 --> 00:53:29,596
Go ahead and pick your
dollar amount, knowing only

899
00:53:29,596 --> 00:53:31,976
that the category
for Final Jeopardy is

900
00:53:32,516 --> 00:53:44,546
[ Laughing ]

901
00:53:45,046 --> 00:53:45,286
>> All right.

902
00:53:45,286 --> 00:53:47,766
So you put your dollar amount
down, as have the staff.

903
00:53:47,916 --> 00:53:49,496
Okay, no changing
your dollar amount.

904
00:53:49,936 --> 00:53:53,426
Your question is this.

905
00:53:55,516 --> 00:54:24,906
[ Music ]

906
00:54:25,406 --> 00:54:25,996
>> All right.

907
00:54:26,316 --> 00:54:33,206
So students wagered all of it,
2800, which will bring them

908
00:54:33,206 --> 00:54:37,036
to 5600 and the win if the staff
do not wager more than that

909
00:54:37,036 --> 00:54:39,706
and get it right,
and their ans --

910
00:54:39,836 --> 00:54:43,346
extra time for the
staff apparently.

911
00:54:43,346 --> 00:54:44,486
Should I just read

912
00:54:44,486 --> 00:54:44,686
>> [Inaudible].

913
00:54:44,686 --> 00:54:49,906
>> No, that is incorrect,

914
00:54:50,126 --> 00:54:53,716
because if the students
did get it,

915
00:54:53,716 --> 00:54:57,506
this is of course Rot
13 for, for the win,

916
00:54:57,506 --> 00:54:58,716
and the students
have indeed won.

917
00:54:59,516 --> 00:55:06,546
[ Applause ]

918
00:55:07,046 --> 00:55:09,286
>> So go ahead and stay
here for just a minute.

919
00:55:09,286 --> 00:55:12,946
We have one more song for you
today before cake is served

920
00:55:12,946 --> 00:55:15,536
up in the pub downstairs.

921
00:55:15,536 --> 00:55:18,546
If we could dim the lights
for this final moment.

922
00:55:19,676 --> 00:55:23,346
We give you CS --
you never been --

923
00:55:23,346 --> 00:55:26,566
normally you can't wait
to get out of here.

924
00:55:26,826 --> 00:55:29,576
All right, this is CS50.

925
00:55:30,516 --> 00:58:02,716
[ Music ]

926
00:58:03,216 --> 00:58:03,766
>> The end!

927
00:58:04,136 --> 00:58:06,026
Cake is served downstairs!

928
00:58:06,056 --> 00:58:06,906
Thank you to all.

929
00:58:07,516 --> 00:58:14,440
[ Applause ]