CS50x 2024 - Lecture 5 - Data Structures

***
This is CS50, Harvard University's introduction to the intellectual enterprises of computer science and the art of programming.
***
TABLE OF CONTENTS
00:00:00 - Introduction
00:01:01 - Stacks and Queues
00:09:53 - Jack Learns the Facts
00:12:01 - Resizing Arrays
00:30:33 - Linked Lists
01:16:09 - Trees
01:30:34 - Dictionaries
01:34:26 - Hashing and Hash Tables
01:52:36 - Tries
***
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LICENSE
CC BY-NC-SA 4.0
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Public License
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David J. Malan
cs.harvard.edu/malan
[e-mail]

[@oskartrinh6001]

Just finished watching lecture 5. Now it's time to watch it again like 3 more times. :D

[@sultanghani7356]

This man is doing more work than the hardwares.

[@evachen4709]

I've watched CS50 2023 to get started with some concepts of CS and now cmoe back to 2024 from time to time to see David explainging some specifiec concepts when I bump into them when solving problems. Really honored to have David, CS50 series and the team. Many thanks.

[@wsollers1]

As a seasoned developer, I use these videos to augment my son's curriculum. This is invaluable knowledge laid out in a clear and compelling way.

[@Rodrigo_Pimenta]

Can you elaborate? Why is it valuable to say on your curriculum that you whached the CS50 online course?

[@ousseynoukone]

​@@Rodrigo_Pimenta You'll receive a certificate at the end... A certificate that carries significant weight. CS50 is one of the top online courses for an introduction to CS.

[@anshuraj4277]

Is there any Python DSA course U can recommend

[@anasanas7842]

"I have no idea what im studying" lol

[@sahil-anurag]

yeah! i have noticed. lol😂😂

[@pavan7335]

Intro music is a banger!!! Whoever composed it, hatsoff!

[@parthdeshwal4419]

indeed

[@shinthantkaung]

I luv it

[@Aman-fz1ew]

Top quality demonstration .

[@Shawky.]

Happy New Year and all the best for 2024 ! Happy Coding 😃

[@blessdarah1256]

This was such a wondeful course. Well put and in very simple terms. If you already have a descent understanding of DSA and some C, it's going to be flawlessly easy to pull through the course.

[@aftertwentea]

This is it, the stumbling stone of CS50🎉🎉🎉

[@villagerdude2989]

Fr 💀

[@bassycounter]

What exactly do you mean by “stumbling”

[@misterguy]

@@villagerdude2989all I see is everyone loves these lectures

[@lintz_lin]

@@bassycounter Late answer here but I think it's because this is one of the hardest part of the CS50 course, if you get past this block then you'll be very likely to finish the whole course. Some people unfortunately give up at week 4 or week 5.

[@bassycounter]

@@lintz_lin oh okay, makes sense. I find it very interesting and refuse to give up until I finish, just turned in week 9 and about start final project once i get everything properly setup locally. Wishing the best of luck and good vibes to everybody else!

[@sefonefinpsefnpefn4191]

finally finish this video! keep going guys!

[@omowomaroland1880]

Truly very simplified approach

[@johnmayfield7662]

I loved the balloons explanation Mr. David

[@fest8177]

We’re back again with this hellish week 😂

[@DTALKS01]

Amazing explanation of hash table

[@fbiagent6081]

Where was this when i needed it 😭

[@andoryu14]

I recall people saying week 3 or 4 were the hardest, but this week has really deflated my sails and I'm not even at the pset yet

[@nanoalt8127]

this one is giving me a headache trying to understand pointer arithmetic. I now see why people call C an archaic language if you're new

[@bassycounter]

Yall got this!! Just keep watching lectures and sessions and read the notes if needed.

[@andoryu14]

Update: finally submitted the final week 5 problem more than a month later. Hardest week so far for me by a lot, but getting this far has taken me 9 months to do 5 weeks of problems. Don't give up!

[@bassycounter]

@@andoryu14 Well done! Speller was certainly a tricky one, I’m not even sure if I’d be able to easily redo it if I were to try it again, but to be fair, a lot of these problem sets are really hard to FULLY digest within only a week, they’re mostly just things you get better at by repeating over time to get more comfortable with. Just a few more weeks to go! The stuff with Python is a breath of fresh air, I just got to the final project about a week ago, still haven’t made much progress with it if I’m being honest since everything is coming from scratch and I’m having trouble with planning out how I want everything to look and work, but I think you’ll like the next few weeks, especially the week with SQL, that was a fun problem set.

[@vwhxss-390]

​@@andoryu14 Cool bro I just finished week 4, wish me luck

[@WizeChoice]

So Amazing 👉🏾✨✨✨

[@abdullah.astro1]

شكرا ديفيد واخيرا خلصت الاسبوع الطويل هذا وبالتوفيق للجميع

[@philippwiederkehr7262]

I liked the balloons demonstration!

[@cybrd230]

It suddenly started making a lot more sense.

[@thankyouthankyou1172]

I like how well the lecture was prepared: handing out cookies to demo FIFO

[@huropjohe2922]

1:15:00, I think if node's number is equal, '=' can be add at line62 or line41.

[@user-gc9sp7bx5z]

Dave has done more than 90% of profs out there. respect.

[@kuldeeppal7229]

Today is my exam, wish me luck 🤞

[@aasrp661]

Yes bro good good exams. 😎

[@alainrouleau]

This is ALL pretty crazy in terms of low-level languages like C. And makes you wonder how anything actually got accomplished in the good old days. They no doubt wasted a lot of time on just simple stuff. The equivalent would be of someone wanting to go to the grocery store. But wait... Oh ya, that's right, first I have to build the car, LOL Thank god for high-level languages.

[@budiardjo6610]

i am glad he is using c language

[@antonioskokiantonis7051]

Ok, thank you C, we're moving to your modern child, Python!

[@ProgrammerPenguin]

lmao!

[@efei_]

Nice

[@Vhc706]

Raise your hand if you choked up on linked lists 🤚

[@born2fight77]

hi, at the time line 27.57, do we need to free temp also,, line no 29-free(list); ,line no 30- list = tmp; here list has been assigned with tmp, line 31- as per my thoughts - free(tmp);

[@ItsMidNightDev]

I believe at that point 'list' now points to the memory that was allocated to 'tmp', as he set 'list = tmp' on line 30, so 'free(list)' on line 37 is basically free-ing the memory that was once allocated to tmp. I'm still learning this myself so if that's incorrect please correct me :)

[@huropjohe2922]

1:21:27 英文字幕裡的[INAUDIBLE]，因該是mario，馬力歐，前幾堂課舉的例子。

[@DebopriyoBasu]

Thank you for sharing this online. Time to fix my knowledge gaps.

[@AudisioOficiaI]

how are you verified???

[@ProgrammerPenguin]

why are you verified?

[@aidanthompson5053]

1:14:22

[@jerrypro9454]

57:50 Is it just me or atoi function was never introduced before in the lecture?

[@paiksprod8358]

Atoi was introduced in problem sets, probably in week 3 as i remember because i used it myself before week 5. In general problem sets requires sometimes more than just watching the lecture

[@AhamdMQ]

what if we have more than one person with the same name when we're using Tries?

[@oteikwufrancis1108]

A simple question dear sir. It seems, once cursor->next is converted from NULL to n we loose the pointer to NULL. So how do we set the last element in this list to point at NULL? Me thinks the pointers if a node is created without assigning it a pointer, the pointer is implicitly set to NULL. Am I right?

[@poggybitz513]

No. It could be set to garbage value. You need to explicitly set the pointer to NULL.

[@oteikwufrancis1108]

Thank you sir @poggybitz513 . It seems that wasn't done in the code we were given.

[@asrarlone8660]

is it full dsa course

[@wanderingfido]

8:02 It's misleading to use method names _push_ and _pop_ because those are the typical functions for an array. During which the more cpu-intensive operations of shrinking and expanding the physical size/length of an array is committed. The _get()_ and _put()_ methods more accurately imply that cells/elements within the queue are _overwritten_ or non-destructively _read_ as per index values updated within _head_ and _tail_ integer variables. While the size/length of the array remains fixed according to a _CAPACITY_ value.

[@Nanagos]

I didn't even notice until now, that David Malan is wearing the same thing all the time 😅

[@CptSamel]

This dude is still losing sleep over how the balloon demonstration went but to me it seemed to go just fine 🤷‍♂

[@bikashtamang9756]

even tough he is explainging in such a goood way don't know why i am not able to understand it

[@King_504]

I think he's a tad bit too animated. gotta weed through his fluff to get to the actual message he's trying to convey

[@aidanthompson5053]

1:37:25

[@emilsjoblom273]

what do you mean?

[@ProgrammerPenguin]

@@emilsjoblom273 comments appear top for the commentators so its prolly a note comment for later.

[@shinthantkaung]

[@80greaty]

He earned my respect when he pronounced valgrind "val grinned"

[@IHateMondaysToo]

makes me think of norse mythology

[@mohamedibrahim1836]

First of all great efforts and brilliant content! That said, I am always fascinated with how educators can make simple concepts sound like they are talking statistical mechanics or some sophisticated topic! I am not sure if the impact is to keep students alerted or the average students will be thinking ooh this is so sophisticated and result in anxiety! not sure! but what I am sure of is that these are pretty average logical informational topics like most of computer science subjects and they don't require all this excitation!

[@phonixMAM]

they dont if youre chatgpt

[@svengoerdes1705]

Well in my opinion this excitement and playfull approach is one of the best ways to keep the students concentrated and interested. Excitement is not required but it makes the lecture so much more interesting. You could say the same thing about every subject in school. Compared to your knowledge almost everything is "average". However, it is not to the students! So please rethink your opinion and try to avoid calling information "average".

[@IRONMAN-to7yl]

38:06

[@syedzainulabideen4455]

1like = 5pushups in 2024

[@theXsun]

You say that on every lecture

[@aliakseivasiukovich8244]

How much money did Nintendo pay for the commercial? Almost every lesson mentions Nintendo characters. The course is great, though. Just my observation

[@ProgrammerPenguin]

no, it's just an example to better connect with the students as said by professor David himself, he also uses characters like binky and oscar the grouch!

[@MooseGoWoof]

Anyone else watching at 2 times speed?

[@Aman-fz1ew]

Nope

[@bekay7663]

I get distracted if not lol

[@bekay7663]

​@@Aman-fz1ewyep

[@DarkDevilVaqif]

why is he adopting and putting kids up for adoption

[@user-ut4zh3pw7l]

overengineered sorry bs

[@einfacherkerl3279]

I don't know why he had so much drama instead of the actual knowledge. He spent good 35 minutes distributing cookies while barely discussing stack and queue. Time thoroughly wasted

[@saqib7685]

Because it doesn't make us feel bored.

[@andrean40]

Go watch any boring lecture then, no one dragged u here

[@romievthedon]

You never freed tmp, via free(tmp), 29:00. I want my cookies😂

[@nitinkashyap2619]

he mistakely free(list) again inside free(temp)

[@cklai350]

list and tmp here are pointing at the same chunk of memory. Thus, you should not free it again.

[@romievthedon]

@@cklai350 Ahhhhh, okay. Thanks for the clarification😅 I still have yet to toy around with C. I've dabble with C++ for unreal engine but that's about it. I expect to use C officially when I start working with embedded systems in the next couple of weeks.

[@aidanthompson5053]

36:57

[@anasanas7842]

1:39:40 1:41:45 1:43:32

[@charlesabju907]

I wonder what he actually said in the live class instead of Lakitu

[@angiehidalgo5190]

@@charlesabju907 I NEED ANSWERS