Live Mock DSA | GeeksforGeeks

Key Takeaways

[Music] so [Music] [Music] [Music] [Applause] [Music] hi and welcome to geeksforgeeks today we have yet another mock interview session with sri lanka so before we start let me introduce myself hi everyone i'm siddharth currently i'm an sde editor and mentor at geeks publix now without any further adieu let us add sriram hi sriami how are you yeah hello i'm fine what about you yeah i'm fine too so today now we would be having the dslr that i would be giving you two questions and you you uh while you are solving suppose you are not able to solve or you are not getting the idea you can ask me for hands and i would help you throughout the way okay so can we start yeah sure okay so let's start with the introduction from here can you please introduce yourself okay um i am sriramu i am currently pursuing my vtech engineering mechanical engineering at national institute of technology surat kal and i am currently at my third year and i am passionate in coding and problem solving and also quite involved in development projects have done a few development projects and uh that's it so can you talk a bit about your development projects yeah like um i like our college used to have many clubs and those clubs will be having their own websites to showcase whatever they've done throughout the year their achievements and their ongoing projects so i have done my contribution in uh developing those blogs and um like uh creating those uh databases of records using um like um database softwares like mongodb and all those stuff and also um i've built most of my websites most of the websites i have contributed has react js and that's okay so how how much would you rate yourself on a scale of 10 on react um yeah on place of react like most of the projects that i've done under is under my 100 uh guidance of my seniors so uh so i will rate my knowledge on react like maybe five on ten because there are a lot uh many of things that i should learn in reality so that's that's absolutely great so now let me share with you yes so i have given you a link please open that link turn off all your notifications and then share your screen wow is my screen can you please share your screen go to the stream here go to share and then you can share the screen according to your needs yeah absolutely correct okay click on the ok button that was given yeah make it full screen like okay you can see in the world just increase uh this is just increase the font size okay while you are writing i would do it that's absolutely not an issue so the question is that you are given a binary search tree okay so do you know what is binary search string yeah binary search tree is basically a tree which has just uh where each parent can have a maximum of just two children two children nodes and um the left side node will always be lesser than the root node and the right side node will always be greater than the root okay the left side so that there would be a root and the left side would be having the smaller values and the right side would be having the larger values this is what you are trying to say yes will this be applicable for all the nodes or just for the root itself yeah for all the notes okay thanks a lot so you are given a binary search tree and you need to print the k largest value okay [Music] so what i will basically do is uh yeah uh how you finish the question yeah and this is the whole question right is finished right there are no more uh constraints from your site right no see just what you need to do is you can you can output so let's make it a little bit more intuitive you need to print the sum of it okay you need to print the sum of j largest element in a bsd this is what you need to do okay some more first larger elements so like if in a normal array if that is the case once yeah so here basically i this is the normal array for example so what you're asking me to do is uh we need to print the sum of the suppose suppose suppose you are given the elements as one two three four five six okay yeah okay yeah then the value of k is 2 so that would be nothing but 5 plus 6 okay okay suppose the value of k is equals to 3 that would be 4 plus five plus six yeah okay okay yeah yeah you can move forward yeah so how do you intend to solve the problem um so first i would try to find the sum of the whole tree means one plus two plus three plus four plus five plus six uh by using uh inaudible okay for initially finding the sum of the whole tree then what i will do means i will inorder traversal till i reach n minus k elements for example here uh if so how how would you know that you are reaching the n minus inner and i will be having another one variable which is passed through address like a static variable or something which keeps increasing for a uh each element that we uh like find in that particular recursive call and so when i am reaching the uh fourth element um means the n minus kth element yeah i will be knowing right so i what i will do means i will just from the whole sum i will be uh taking the difference of the first and minus k elements so which traversal would you be using [Music] mostly i will go with inaudibles okay so why not post order traversal um because in inaudible it basically travels the array in uh sorted order so i will be knowing where i should stop exactly right okay that's great okay so now i would be pasting the just a sec okay we can start coding from this point okay yeah so i will make the fonts a little bit bigger i hope the viewers can see it if you as viewers are not able to see it please let me know in the comments okay so yes yes everyone's everyone is correct in the comments i can't repeat the comments tell i'm finished with this question okay thanks a lot okay fbi secret isn't okay okay okay that crc okay we would be talking about that at the end okay so this is a learning thing like first he would be performing like i can't just try to force him do this to them first he would be performing okay and then i would be giving him the feedback so that he can improve the next time but if he starts performing and i'm start i start telling that please do this at this point that object point it is not feasible other person would eventually get irritated or demotivated i think so as a human so the methods are that to go on the left side you need to use left to get the date so get the data of the node you need to have use the data and write is that your secret agent is interested in coding to find the local engineering system to change that okay might be the scenario so let us see what he is trying to do so in the explanation by sri rama he mentioned that he can pass by reference or a static variable so you can can any anyone from the viewers tell us that what do you mean by static like what is the basic basic use of static just the basic use i don't want any vocation information how can i join live mock you can join the live mock by going to the description of this video you will find out google form link fill that google form link and then you can apply static is fixed which can't be changed in function after initialization okay i don't think it is the most appropriate one anyone else okay i should make this a little bit smaller so that we can see what he is trying to code all the way i think the viewers it was feasible okay please so please can you improve over this code viewers what do you think at what parts we can improve this um simplest definition of that okay like you can understand it is not that so i will just display it for once okay now let us see okay yeah i guess okay can you improve over this so what is the time complexity first of all um time complex is uh i it's basically finding and what is the space complexity of this problem that is also often it is using an auxiliary array of the size of the nodes so can you improve over this complexity so improving on space or time because i don't think so on time okay so what do you think you can improve tell me uh i guess uh i may improve on the space complexity maybe yeah i can't okay so try it and tell me before implementing but how can you think well you can how would you try to improve with this so here basically we need to uh find the sum of uh the largest k elements right so as i initially told instead of finding the whole sum and all those things it will be able to just um sum up the last two elements in the inorder traversal itself by using some static variables i think i will be able to improve can you repeat again yeah so basically what i'm trying to say is uh when i'm doing inaudible for example in this example itself i will not increase my sum initially my sum will be zero so i will not add anything to my sum till i reach five but once i i reach five i will be keep on increasing so that's what i am trying to say okay let's suppose you have six sections whatever is there okay so how would you know suppose you are visiting one then you are visiting two then you are visiting three then you are visiting four so at this point how would you know suppose you are visiting the three okay like your current node is three at the moment okay yeah okay so tell me so tell me if this is so so clearly not visible okay just let me check the previous screen just a second because people are telling us okay so i need i will just uh remove the banner okay i think now it will be visible for everyone okay so yes i was talking so suppose you are at the node three current node is three so at this point how would you know to consider that particular three or not yeah so initially i will try on declaring a variable which counts the number of elements which have covered at the particular point of time so suppose you have covered three elements suppose you have covered three elements so how would you know because the root is given not the size is given i hope you are getting my point yeah i i got your point you want the last so what i'm trying to say is for all the viewers you want the sum of last k elements to get the last k elements you need to first either have the size or to have a proper thing like you need the value of that that is the constraint here so are you clear why your approach won't work yeah i got it okay so how would you combat this thing so maybe i will try to do a separate a traversal to find the number of uh notes or the size of the three basically but yeah okay so you would just count the number of nodes which are not am i correct yeah okay this is fine so now tell me that if this is the scenario that we are just counting the number of nodes which is not equal to null then the next suppose the number of nodes is now okay so how would you so how would you optimize over this like the time complexity would be again big of n only but how can you optimize over this like in one traversal you would be getting that you are using true traversal like one for the size of the size of the root one for the size of the whole pst and one to compute your result so how would you do that okay if you want any hints i can help you with that if you go blank just ask um it's a space complexity of at least of case uh is like good or like we should optimize more than that means space complexity of k means uh yeah not k exactly but at least n minus k so is the space complexity so see what is so if you get a problem like this just try to think that what is the problem asking the problem is asking us the sum it is asking us the sum it is not asking us the value okay so see the questions are not made abruptly okay they are kept they are made with things kept in mind so if it is asking you for just the sum is the elements individual elements really required or you just want the sum like do i really require five five i do require five plus six eleven or five and six and then add it up try to think in this manner are you getting what are you trying are you getting what i'm trying to say yeah i'm getting okay like the individual elements is not really required what i what i'm interested is i'm just interested in the sum i'm just interested in the sum of them so don't really need to bring out all the k elements individually present it in an array or a dynamic array and then add it up you don't really need to do that just try to think something if you go blank let me know that's absolutely fine okay okay see just try to think in this see just try to think in this manner okay you went in the correct direction you are in the correct direction okay this is uh this is a bst and you told that in order traversal of a bst produces the result in a sorted form yeah you told me that now try to think in this direction that how can i get the reverse sorted like i need to sort it and then reverse it without directly not for sorting and then reversing i don't want to do that what i want to do is i want to directly traverse the vst in such a way that i would get the reversed sorting try to think try to make use of the properties of bst try to make use of the properties of these got it so instead of doing initially uh left middle and right we can go right middle and left right middle and left try to do that further okay so now there is one more thing that you need to do the next thing is i want you to have the values you know i want to optimize i want you to optimize over the space complexity yeah so for that oh so okay so this is the first time that viewers are confused so anyone from the anyone from the viewers okay i would share it it's absolutely fine just ask me uh okay let me see yeah it's absolutely fine just drink some water take a deep breath close your eyes for five seconds and then start acting thinking it happens with everyone it's absolutely so so how many of you liked this question because i like this question very much so let's see [Music] okay only one person liked it so i think this question is a very good question why because it is a variation of the classical sd problems like if you talk about the most task is the interview questions the variation of this the classical one is commonly asked but this one is a little bit good one like if you have really understood from the bottom of your heart the in-order one then yeah you're perfectly let me audible just a sec can you quickly explain your solution to the audience while i'm testing so basically what i'm doing here is i'm doing inorder traversal in opposite way so it first reaches the means the highest element since it goes root right right right so it reaches the largest element and it traverses in a river sorted order so here i'm maintaining two variables which are passed with address which is basically sum and count and if if the currently visited node is not null i will increase the count by one and it is the number of nodes that is visited till now okay once yeah that's it yeah so when it visits a node and we are searching for when for example here i will go to 6 and when i reach 6 i will increase my count to 1 and since my value of count is lesser than k i will um my i will add add this to my sum and i will keep on doing that and after i um i reach values like count equal to 3 i will not add so that's what this if condition is assuring us so at last i will be able to get my online hi can you please do a dry run of your code and see why the our code is not working so your approach is correct i would confirm that but can you see why a code is not working just do it right for a value of k is equals to k is equals to for suppose just one just do it for one and you would say that so first i will start that uh i will start for example at yeah let me guess that i will start at one so i will go to two then two three into four and divide them to and six will not have anything on its right so i'll come back to six and i will increase the count to one i will add my sign then there is nothing over the left like i'm not sure why why is the code is not working but that's absolutely fine i will show you that yeah just let me share my screen are you able to see my screen okay this has the structure of the tree okay or the binary search tree to be specific okay so now if i just give the value of k is equals to 1 then if i run it the sum is 0 and i have also added the value of data so now let us see for the value 2. so the value 2 is given y'all says again 2 divided 3 is given same value 3 is just giving us 21 19 and the sum is equal to 40 but it should count three elements but it is counting one less so if i'm giving the value two i think it would give me one value that does not even give me so according to me if you're not able to figure it out you need to see the value of comment like how the comment is going on yeah actually uh i placed my count uh like after the not a traversal first in order class means after the root right means i change it but i think after that it might work okay save do it should i do it means i don't think so in your screen i'll be able to do that no no i would be doing it what should i do yeah um line number 78 should go below line number 79. okay the value is still zero okay 0 that's absolutely great okay so what does the result just stop sharing yesterday so what is the so what is this i would just share your screen just revisit the solution i'm just pasting the correct solution by you okay hope you are comfortable yeah okay so now tell me that what is the space complexity and the time complexity now now the space complexity is constant of 1 and the time complexity now is of n okay and okay so we are not doing it through traversal and this is done okay so it's 653 okay 6653 so let's not move forward to the next questions next question because as you joined late due to network issue let us end at this point okay so now it's time for feedback talking about the feedback you are absolutely great okay like you were able to like you already knew that the inorder traversal of a pst produces the sorted result and yeah i just gave you a hand i didn't even tell you that i just gave you the hand i just had you broke down the problem and you were able to do it but there are some points that you can still improve the points are that you could have used the root very brute force approach then you could have then you could have optimized it okay now talking about your introduction when you were intro when you are telling me about your projects then you can be specific like of which project you are talking about like your interviewer would be having your resume in hand okay so if you are talking suppose i have mentioned a project of web development in which i have built an ecommerce website and when i'm introducing myself in the meantime i'm talking about some project which is not listed in my resume okay so hope so whenever you are introducing yourself please don't try to talk something out of your box okay like talk with respect to the resume so that your boundaries are well defined okay then the next thing you took very less time to think okay i think that was the point you got confused if you had given yourself more time because i was not the one who told you the solution you also know that yeah you only took out the best solution i was not the one who worked who was doing it i never told anything to you okay so i think so that you can take some time with you like it's absolutely fine the other person who doesn't use your interview like you can can you mute yourself for a sec like while you're speaking like while i'm speaking you can just mute yourself so that there is stuff so see that's absolutely fine the other person taking your interview is also a person like he also works a company he has also given interview he also knows that to solve before solving a particular question you need to think about it you need to think of the solution so even if you take two three minutes i'm not telling you to take 30 minutes or 40 minutes but if you take two three minutes or at least five minutes it's absolutely fine okay it's absolutely fine just if you think that i would be taking more than five minutes what you can do is what are you thinking exp tell your thought process too okay like the next thing like while you are coding okay like you explained your approach the interviewer is impressed enough but after that try to explain at which point you are doing what okay don't rely on the interviewer like you are writing a line and he would try to gain like what is he doing like it might be a case like i'm just telling you my situation okay like i am very accustomed to using array as just a okay to save time but many people who are from the background of lead code or geeks for geeks they have it they have a habit of using a rr so i really get confused okay so it's absolutely fine everyone has a different naming convention of his own okay everyone has that so either you are either you are like you are using size of the array either using self self descriptive variables if not it's absolutely fine then you can tell that see we are declaring n and we are keeping the size of the array in the m like while you are moving forward we are keeping a constant which would gradually increase and at the point of this it would stop like you can draw the toilet before moving forward you can just show you can just draw the tree you can just show it how it is working all together okay like how your approach is whatever let's see try to think in terms of teaching also like you are don't think that you are just giving an interview try to think that you need to make an impressive impressive explanation to your interviewer even if you know the how to solve the problem then not able to explain as a bad sign okay now you can unmute yourself yeah so this was the feedback from my side so any more thing you want to ask from me [Music] like when we are preparing for a particular company yeah can i ask yeah sure like when you are preparing for a particular company which is the best approach like uh like some days before the day of the interview like what is the right approach when we are going for a party when we know the company which we are going to be interviewed like what is the right approach like four days before the interview or the basically the last minute preparation last minute preparation so what you can do is like go back to your school days okay like you suppose you are giving your interview on amazon okay so what you can do is you can go to the recent because you have four days you don't have time to go about all the interview experiences that is lying there in the internet so what you can do is you can go to the recent interview experiences and you can just check in the recent time which topic has been covered the most okay which topic has been covered the most like don't try to go in this direction that is absolutely wrong idea just i would only prepare the question that has already been asked because that is a very rare probability okay that is absolutely a bit of probability so what you can do is you can just write down that yes this question from vstk so yes bst is important this question from inaudible is important okay this person asked dp that means dynamic programming is important do i make sense to you sriamo is freezed for me it is for everyone else or my network is freezed let me just check okay okay his network is crazed okay so sriramul you can quickly unshare your screen quickly and share your screen so that your network would be good enough okay now i think yeah that's absolutely fine yeah sriraman you were able to hear what i what i told like what is uh other than on campus um opportunities for internships like what is what are the other sources that we can try for uh getting an internship during our college days like third year okay so so if you're prepared enough i see a very good resume that we are well prepared in dsa so what you can do is as of now what i did i'm just telling you the way i did so what what you can do is you can move forward and suppose this is off campus so you can start applying okay but off-campus internships are a little bit rare okay like your little a little bit rare so what you can do is if you are not getting your resume selected you can start you can start giving your to the recruiters okay like to the recruiters of the people working in like suppose jpmorgan or amazon you can tell them okay you can tell them that yes this is my resume i want to work like you can build up a template out of that and you can keep forwarding to everyone but make sure you don't just write high like the template should start with high sri rama okay so this gives us a sense that yes this template is personalized for me don't just have a template written hi and then the whole your resume attest and the whole thing written and you are forwarding it to everyone okay i according to me writing the name after the high gives the gives us a sense that yes this template has been curated for me so do i make sense to you but okay that's absolutely great any more thing you want to ask um yeah thank you that's it from me okay thanks a lot it was absolutely great interviewing all the best for your future man so that was it for today we would be meeting again with yet another knock interview hope you have enjoyed it if you found it fruitful and if you found it worthy enough make sure you like the video and comment on the video so that the reach of this video could be increased thank you everyone you