Hello Henry. How you doing? Nice? It pretty good. Good. How was your week? Just as usual. As usual. So, so good. Yeah, very nice. That's good to hear. What did you do? What did you do this week in computer science? Don't think I was studying other subjects. You have exams. Yeah, this Friday. Friday. Okay. Well, that's well, that sucks. I hope it goes well. I'm sure they will. Thank you. Okay. We're going to start off. I'm going to try and make this into a pattern, and I know it's not that fun, but I really think we need to work on it. Please answer me long form this question in quote, unquote, exam setting. Five points. Let me give you permission. If you could please answer this question, let me make it bigger. And then we'll go over it's five points and then we'll go over of this. Sorry. Yes, this is in my syllabus. I don't it's chapter 10.4. You have abstract data types. It's where I get everything. I look at the syllabus so it doesn't need to be very very detailed. Think about what abstract data type is. Yeah and I definitely think can get this because we've you've used them before whilst programming so I'm not too worried as long as you can figure out what abstract data type is you'll get this right. Wait, sorry it's a no nothing. I couldn't type for one okay. So I have to describe how they work. So maybe give two examples and then describe how they work. So I can just explain what type of container it is and what functions it has. Perfect finish. Okay. So the answer to the question is not correct. Unfortunately, you would get zero points here. However, Henry, I want to know if you had got an abstract data tacorrect if it was as you see here, a class with member functions. So this what you were describing is more of a well, I mean to be honest. Here you're mixing classes. And you're mixing data types now. Now here's the thing. You're mixing them both. You got to it's it's it's it's so getters and setters makes me think of classes. This is a class, right? So in a data type you wouldn't necessarily have getters and setters, right? But then you talk about tharray face back. Then you talk about emplace back and a vector, which is adt abstract data type. So you could get so where this is good, you understood you gave an example of a class which is used like a data type, like a vector, right? And if you're your professor, if someone knows what you're talking about, you get one point here. Maybe, but let me go in and tell you what an adt abstract data type is, and then maybe we can redo the question. And I want to say, by the way, the way you answered the question is very good. It is a container that has mmember variables as private members and public member functions like others and settters to access to modify them. If you were talking about a class here, that's two points already. A vector as an example that sourres this data in urora and allocate new memorized data as processed. Yeah I mean if you were talking about a class here and it was talking asking you to talk about the vector class in c in C++you would get four to five points. So your what is good the good news here is you've got the answer question structured correctly. So good job there. And you know what a class is and you find a way to relate it to data structure. But a data structure is something like this, right? Data structure. Is equal to an adt abstract data type, right? So if you see abstract data type, then it is a data structure. One example, binary tree. Can you give me another example of an adt? List list link to list specifically Yeah. Okay. So I know I'm I'm sorry to have to do this, but would you mind answering the same exact question? But now but now you know what an adt is. So could you explain it again? Sort. So now you know that an abstract data type is something like a binary tree or a linked list. Where are the five points from in your opinion? One is from the data type and the risof, the four describing the single two of them and how they work. Yes. Is there a like standard defindefinition for adt? Let me get it up for you. Very. This is the definition of an adt. An abstract data type is a mathematical model for data types defined by its behavior semantics from its point of view of user data, specifically in terms of possible values, possible operations on data from this type, and the behavior of these operations. That's really what you talked about during your vector here. A vector is a new data type that has in place back, right? Because you can in place back, it has a unique pointer that stores temperate creset or the rostate container or something with its own access functions. Exactly right. So so for example, inside of like vector, right, vector dot N Q. That's very good. The only problem is you have to keep it in the scope of your syllabus. So instead of this, so unfortunately, this cannot not be used to answer the question, right? So when you think about the question, you should really think, okay, four for the definition. So here you don't have to write this thing. Here you don't have to write this block. You can just say an abstract data type is a method of storing data, which makes accessing it or adding data to it useful for certain operations, right? Or however you want to put in their own words, because you kind of already understand an adt, right? Or you could always make like flash cards with all the definitions and provide two examples of them. You've got two up here, but I think you can provide two different ones. So I'm going to ask you to provide two different ones and describe how they work, right? Very easy. Linked list. You can add. You can literally say one example is a linked list. That's one point. In a linked list, you can add an infinite number of notes as they are stored randomly throughout memory. Boom, two points. Easy, right? Does that make sense? Yeah. With that in mind, sorry again to do this, but please re answer this question and then we'll move on to lead code questions or maybe we'll do one small thing then move on to lead code. It does to have some sort of raw data type in it, right? It usually does, yes. So most data types are going to have some kind of of raw data. Of course, inside, like for example, binary retreat might be numbers, but it could also be strings. So it doesn't necessarily have to be just strings or something or just numbers. I'm just going to refill my water. If I can't say vthen, I would just say dynamic array. Yeah dynamic array dynamic array you can say linked list is is more is more Yeah Yeah No But I mean for a map it contains a Yeah Yeah Yeah that was sort of general and non specific Yeah you're actually you're absolutely right. Yeah that that would be good. Just remember though recruit people that are marking your paper or not necessarily computer scientists do keep that in mind. So the simpler language use, it sucks, but that's how it is. I just say name the function or should I. Should I just say a general type of function? General type of function. Don't name any functions in C++. No. Like just thought find would be general one. Yeah, exactly exactly like in a map. But you might borfind this. Yeah Yeah finders would be good. You could even sit or hash because you know if you talk about hash values or like a Hasher. The stack also contains a dynamic area. It uses a linked list dynamic array. Yeah. What should I say for the functions then? Pop, Yeah, Yeah, exactly. That's a very, very good one. I think I be a trade. Yeah, I think I think here you get five Marks. Very nice. So you explain what an adt is. You give two examples and you basically say how they work. You can function, find it, the hashes to athe user and other things that will with text can a dynamic. But can I ask the top of value functions are used for more about these values? Okay. Now you would get five points here. If you have got a mean person or someone who's maybe stupider, they would give you four. And the reason is not because you got anything wrong, it's because of the way you explained it. So let me show you how I would reply to the questions. And again, this is a correct answer. So good job you've got it right. But I want to show you how I would reply and how you ruit a marker will read this and try it. And the best way to basically give them an answer. So here I would say an abstract data type is a method of, is a way to store data in order to make it easier for a programmer to solve a problem of some sorts. One point there, we put point. No need to talk about setters and getters, but that's what I would put for one. So then two points here. An example would be a stack. So that's one point. One point here, a stack works by adding values only to the top using the push function and remove only flowing values to removed via the function boom. Then A Q ue is another example of an adt. That's one point. And then one point here, A Q allows a user to push data to e end and process data at the front push shing using push function. We process data at the front using the boom. That would be five points right there. Does that make sense? Why, it would be five points. So really try to think about this kind of structure here, one point there and then you can boom, okay, at a four more points to can get a point here and get a point here. So I just need to find two more points probably by explaining them boom. So really get into that mindset of where are the points? Where can I find them and try and try to answer them step by step. Okay, very, very nice. Let's do one more long answer than let's do the actual interesting stuff. Okay? Okay, let's not do that because I don't know if you've done yet. All right, this this one is boring, but it has to be done, please. Does? Please describe what an operating system does. We're going to make this worth two points. All right, go for ating. Or I can switch the second one with the file system. Oh, very good. Two points there. You basically gave two main points, graphical user interface and the base for software tranpage you executed. These are both very, very good. Another thing that you could talk about here, no, this is very good. This is two points. I wouldn't change much. Maybe I would say something about the base for software to be executed, right? So maybe I mean, to be honest, no, this is pretty good. Yeah, good job. That's a two point question. You would have gone that one, right? So really try to get into the dimension here. So one point here is an operating system provides user graphical interface that user can interact with. Yes, that's what we need. Graphical interface is questionable. Usually I would keep it to interface as some Linux operating systems are not practiable. But you know, graphical interface will not lose you any points. It also provides a base for software to be executed is perfect. You can say software and services, but it's very good. You would get full points here. Good job. All right. Shall we do some code? Yeah if you want if you don't want to know oblithe gwant to okay, okay. Very nice. Oh, you're doing some some licode heminggweights problem. Yeah, no, it's last the thing we did last time I found it sort of okay for to do it. Another way to do it. You went numfour. You end it with n minus one. Yeah, I see. That's just a bunch of ones. And this is a zero, then it counts. That doesn't really a to be. That's pretty smart. No, it's pretty smart. Need no less memory as well. Yeah. All right, let's keep doing easy these I think you're getting ready for a medium but I want to keep it to easy is the reason being it's just easier for the lessons we have but I think to be honest, next lesson I might we might take a medium see how you do there. So let's have a look. Let's keep going. Let's keep going. Click on. Rising temperature, 197. Oh, no. Oops, no, not this one. Equal. Yeah, Yeah, no, let's not do. Ssequel. Sucks. Alright, let's keep going. Keep scrolling. Valid anagram 242. Think we did this. We did this, okay, like the one with two lists now. No, not quite. This is different. I think Yeah, this one's different with two lists. Oh, you mean the one where we had the mappings, right? Yeah, Yeah, I think I think this one is different. I think this has a different solution. Let me think for a second. Yeah, I think this one, I think this one has a different solution here. So it's not the exact same and it's not the same method. So I will not try to use the same power to and use it the sort of same letters in it. So here it says, Yeah so the total amount of letters, Yeah Yeah. You've already got the solution in your mind. I do think it's useful. And then you know what? If you solve this quickly, we can try and find a medium for you. I'll actually look as you're solving it that way, I can try and find a good medium that we can do. I don't know, a good way to do this though. I would think of abstract data types. I'll tell you that much, you're brain have to use them. But I'm just thinking of a more efficient way to put. I'm just looking for problems in mediums for after. Good wood. But would go. What happened then, I don't know. That my mouagain. Oh, right. Where was it? Like it was something? Yeah, the 40. Am I moving your mouse right now? No. Okay. Weird. Oh, that is weird. Oh, my God. With also, well, I'm going to give you the the data type you need. You need a dictionary. Why I'm. Typing in here for some reason. Great downloading slot for me for some reason. Are are you clicking shift? Shift click? No, I'm not looking anything but. So now if I shift click, I'm good. Now if you shift click and download sometimes, or you control click. Yeah, but now it's I'm not doing anything, but it's messing me up. I have no idea. I'm I'm not touching my key, my computer at all. That is weird. Or if I put it into no, it doesn't work, my search bar is broken for some reason. Yeah let's coand now if I shift click, I enter it. What the hell? That makes no sense. Okay, let me, let me search it. Shift click. Or should I just restart my computer? Yeah, maybe you should restart your computer. I'll wait on the class. Restart your computer, and let's see if that fixes things. Back and it works. That was a very quick restart. Very nice. Yeah let me give you back permissions. Just screen sharing, sharing this solution Yeah, because it seems to break your laptop every time you screen share. So I hope it's not gonna break your computer. I think things, but the applications 's not made pretty well. Yeah, I think so too. It's a map map shmap, no, this map. I mean unbodered, but. I mean, there isn't a dicinary though. There's only standard map and standard unordered map. Yeah you can just use a standard map. I mean, I would and try to think about this as why would you use a map reads. I mean, there has to be some smarter way to do it. I think I have a method. Yeah, this is pretty good. So this works right? Well, you need to do just the last check, but I think you're on very much the on the red track. But this works Yeah this this creates a map and I think this does exactly what you think it does without revealing it. But how do you get to the final false answer at the end there of whether it's an anagram or not? Because this store is on sign chart, so it's going to break immediately after. So. So if I do try and catch. What happens if. If si is not in your map. It adds it into it. It's okay. I mean, I don't know, this is. Almost I don't know though it's because of that I couldn't hear that. What's what's the problem here? It's not detecting what it's supposed to detect. How do you know at the end if you have an anagram or not? What should map look like at the end? All zero. I how do you so right now, you do basically everything correctly. You have a final counts. So you just need to check at the end if they're all zero and then return if they are and false if they're not. Yeah, I'm thinking of a way that I don't need to cycle through the whole looagain. I think inside of map, don't quote me on this as I don't know C++as well, but you can cycle through through the keys only and not have to cycle through the entire string. So that should only have you cycle maximum 26 times, right? Which is constant time because there's only 26 letters in the alphabet. There is, but like. I don't wait. Does it happen? Doesn't have it doesn't have that. Let me take a look. There's a look up and there's the literature. I'm looking it up right now. I'm asking my trusty friend ChatGPT, yes, you can do this. You can do you can literally do like a for loop like this let me let up for that's what I don't want like it's yes but okay I'm yes but also reference that and it's gonna give me a standard pair but I mean I don't want to go through the four again let me ask you the question. Yeah let's say let's say n the number of characters is ten to the power of 20, right? Yeah. How much is this loop? How much time will this loop take? Ten to the power of 20, are you sure? Yeah, it's zero. That's this time. It has zero one access time, right? But what is what letters can the can they actually contain the anagram? Only maximum is 26. Yes, it only it can only have a to z, which means there's only 26. So even if there's ten to 20, ten to the 200 items inside of the string, you're only gonna to have to do 26 loops to check your map, which is pretty quick. This it's what we call a constant time is never going to increase exponentially. So I would be pretty comfortable using this approach here. Maybe start with that, see what your results gets you and then we can optimize once we have the solution. Okay, then it's going to be easy, but I just don't want to cycle through the whole thing again. Yeah. But again, you're not cycling through the whole thing, right? You're only cycling through the alphabet letters. Wait, but then if I cycle through them, I wait, know that's a home. Did I just put a break ke there? You can sometimes I'd like the pythons, like else, function here. Pthon is good sometimes. But here you're very, very close. Think about it. If you don't, if you, if you see a zero, if you don't see a zero, then immediately, what does that mean? Right? I think is the other way around. If you, if you see a zero, if you don't see a zero, then return one, otherwise return zero. Give that a quick run. No, I think my way was actually sort of right, but it just some. So. Right so it's s dot size. So. So if if they're not the same size, Yeah, that's fine. Science. Wait so zero is zero is false. In this case zero is false and one is I see I see I see in okay because when I return zero from a function, I see that as Yeah Yeah that's I don't know why size net time succeeded. Or and I sign sign map. Yeah. And then I changed that to so here, something to think about is. Is if they are not the same size, then should you even run this at all? Will they ever be anagrams if they're not the same side size? No. So I think here a check would be not the same size. In return. And then size here is is needs to be like s dot size or something. Yeah. Zero sending why it is that? So s dot nine t dot size two, then you want this to be zero zero is false. So if it's the same size and it's. So if it's zero, so if s dot five is minus t dot plus zero not zero. But zero is right now zero is false. Zero is false. Zero is false. So if as osilence set with that, so if it's not equal, it's gonna just return one, return zero Yeah if they're both, if they're zero, then you don't run it, right? Yeah Yeah maybe this will be better. Okay, nice. Let's have a look at what we can optimize here. So memory wise, good job. Most people, what they do is they keep in track of two maps and then compare it. Yeah, you can do unit eight. Unit eight. Yeah. No, I got I have it. Then you have 16 char. Yeah, you need the char there. Unt, 16. No, you need 16 because it can go quite high. S I I. Maybe let's have a look at what other people submitted and try to optimize from there. Of course they use Yeah so it's it's a very similar instead of using an array, they just instead of using an unordered map, they just use an array and they use the ascii value of a and b. Oh, and they cheat. Yeah Yeah stuff. It's easy to cheat too, you know. Yeah some of these people are Yeah, they're cheating. Yeah, it's the same method I did that. Yeah, you did a good job there. Very right. I can do this. This saves like for Auto Key value, hash value. Isn't that the same though? What's what's different from this approach? Value not equal als zero return. I have to call second and so you have to call that. But then this is quicker. Yeah because we've got the value already. That's decserirealized. Yeah that is useful. What what does that give you in terms of runtime run that. Oh, he thought it should be mapped, not hash. Yeah, you're right. Yeah, pretty nice. That is quicker. All good job again. Next time we'll do a medium. I'm going to try and select not not an easy medium, but I'm going to try and select a medium. And if you don't succeed then there's no problems there. But I think it be quite good to approach some different kind of programming problems. Another question is Henry, are you enjoying this? Is this useful too? Do you think it is useful in terms of some of it? I mean, I know this works and some of that that I just like like arithmetic logics and stuff, but not actually those specific edge cases that use some container that you won't usually use elsewhere. Yeah, I think that's the benefits here. It teaches you what academic coding is like and also how these structures are used more generally. If you're gonna to do physics later, I think this will come in useful because they have a lot of problems in physics that have high computational stuff. And if you know how to code, well I think it's quite useful. Okay, so I'm glad it's I'm glad it's useful then and we'll keep doing that next sessions. But again, if ever you want na change it up, just let me know and I'll try to find a new way. Okay, cool. Well, great job and see you next week. Bye, bye, bye.