Live Mock DSA | GeeksforGeeks

Key Takeaways

so very good evening guys this is huge khandelwal and i welcome you all to your own channel which is geeks for geeks right we are here for uh again our dsa interview and before starting i just want a small acknowledgement from your side if you can tell me right if i'm clearly audible to you just small hi hello so that may i know um i am audible to you all waiting for your responses guys okay thank you sujath okay thank you ankush thank you thank you very much before starting today's session like you i would love if you can ask your friends to join so that they can also be benefited right but today's session those who are preparing for the companies those who want to appear for the interviews right they would be benefited because we it is going to be a dsa round where we would be asking dsa questions and you would you can figure out what type of questions are being asked in interviews right and when we are asking the interviewee right you can also be solving those questions parallelly at the same time so that you can figure out like what is your approach is your approach correct matching with the approach of the interviewer or not you can also verify those things okay so guys need a permission can we start please type plus one in the chat box if we can start right and i would be calling shall we start just need to type plus one in the chat box okay thank you thank you they worship thank you okay so let me call pavon hey pawan how's you yeah i'm fine sir how about you yeah i'm good i'm good dear thank you so uh i would love you to introduce yourself to our audience so that what is your technical background what you are doing currently if you can tell me and our audience sure sir i am pawan kalyan currently purchasing my bachelor's at vidyan institute of information technology i have worked on multiple projects which were based on purely based on modern development which was my technologies include like mongodb express react.js node.js and i can program in c c plus javascript python and besides that uh we got started for the smart india action finals and besides that okay i mean i'm currently a five-star rated quarter on a hacker rank and a three-star rated quarter on co-chair okay so do you practice on code forces as well do you participate in code forces contest as well yes sir but not frequently okay okay and how would you rate yourself in coding if i ask you to rate yourself on a scale of one to ten right how would you rate yourself yes i would say from 8 to 8 by 10 8 8 out of 10 great that's that's good that's good okay so talking about your projects right you have majorly done your projects on man's tech yes sir so one there was earlier there was a concept of mean stack as well m e a n right yes sir so there a stands for angular and here r stands for react yes so what is the basic difference how react is better than angular where angular actually lagged so that this mean stack was replaced by monster uh basically as far as my as far as my knowledge is concerned like angular is used for heavy load applications like gmail and those kind of applications react is a simpler framework which is used for light lightweight applications and that is actually so by simpler you mean by simpler you means lightweight yes or is it better than angular in somehow some way uh it depends on the application we are designing sir like uh if it is uh heavyweight applications like gmail or that then the traffic is going to be a lot more right so there we use angular and when it comes to lightweight applications we use react and it is easy to learn react very fast as well okay so if i have a website right if i am developing a web app or website and i want that it is going to be accessed by suppose thousands of customer per second yes which platform which which technology i will use uh [Music] thousand news per second sir yes uh i would say angular as it is a heavy traffic i would prefer angular okay so angular decides heavy traffic like the heavy traffic with the help of uh the the fact that heavy traffic decides that whether you would be selecting angular or react actually it is decided by the back end server depends on the server it can handle how many requests it can handle okay good good so tell me tell me about the best project that you have done yes sir it's the project which we got selected for the smart india headphone it is a book your workshop sir book your workshop okay so it was something like online workshop uh registration based system right yes we need to uh choose the bookshop and we can attend that workshop sir like we like we booked the tickets in the movie theater right so in the same way instead of movies we'll be booking the workshops okay so whenever this booking thing comes now there is a problem of the concurrency right yes sir did you face did you face the problem suppose there were two seats remaining for the workshop right suppose there were 100 seats 98s are booked right and two seats were remaining so there were two different people who tried to book those two seconds how will you how will you handle the situation of concurrency that who will be assigned the ticket yes sir uh till now uh actually the final is not the final date is not yet decided we are still working on it working on the project the primary functionalities were almost done and we are trying to add additional features we haven't go through the future yet but that is the most required feature right otherwise it would not be of you it would lead to a lot of uh those problems right yeah consistency problems it's not like uh seats are like uh will be having a frequency of seats whenever someone moves the seats the seats gets ready the seats get reduced that's it it's not like cooking the serial number and kind of thing i'm not talking about booking right i'm saying that you have hundred seat 98s are booked right two seats are remaining and two different users are trying to book those two because two seats are visible to the two different customers right the the users if they both try to access book them simultaneously how you will decide whom should you allocate the seeds that is that is the problem statement yes sir for the statement we haven't worked on it yet we look forward to add it soon okay that's fine yes it's fine yes what about data structures right data structures yes sir confident with data structures algorithms yes sir yes sir okay okay tell me which data structure would you use right to implement a lru cache uh very catchy i don't have much knowledge on alleric edge but i heard that it can be implemented using double inclination okay you have not you don't know how it works oh no sir i haven't worked on it yet okay fine so you have worked in python yes sir but the mostly i use c for the programming purpose okay okay in python there is a concept of tuple right yes sir so if i have like can you tell me that the difference between a tuple and a list in the tuple lists are mutable that means we can change the values inside the list and we can do some modifications to the list but uh in case of tuple it's actually immutable so we cannot change onset code assignment okay so if i am given a tuple which contains a list as an element right yes sir so can i change the list which is present inside the tuple no sir we as we consider the list as an element inside the tuple we cannot change sure about it yes sir i'm sure okay okay but let me tell you for one it can be changed right it can be changed would you agree with me right if i say it would be it can be changed can you think in some other direction like if it's possible or not can you think of it or i'm lying [Music] i'm not sure about it okay okay fine let's start with uh some problems right so it would be great if you can share the screen and start your favorite editor okay you can maximize your editor right maximize your editor yes [Music] okay so i'm showing you the problem right let me show you the problem first what problem do i have right and you read the problem after that let me show you the problem so i have this problem right if you can see this can you see my screen yes sir okay so the problem is swapping pairs make some equal if i go through the statement it says given two arrays of integers a and b of size n and m the task is to check if the pair of values one value from each array right so what you need to do you need to pick one element from array a and another element from array b you need to swap them so that their sum becomes equal if you see here example is 4 1 2 1 1 2 right this is array a array b is 3 6 3 3 right so if i do the sum of array a it is 4 plus 1 is 5 plus 2 is 7 plus 1 is 8 8 plus 1 is 9 plus 2 is 11 right and here the sum of b is 3 plus 6 is 9 9 plus 3 is 12 12 plus 3 is 15 right so i need to swap some elements some pair some element from a with some element with b so that their sum becomes equal so here the swapping is right between element one and three right so if i swap one and right the sum will become here 4 plus 3 is 7 7 plus 2 is 9 9 plus 1 is 10 10 plus 1 is 11 plus 2 is 13 right and here you will have 1 1 plus 6 is 7 7 plus 3 is 10 plus 3 is 13 right yes sir so you need to return 1 right so task is the function uh you don't need to you can input click here you just need to complete function it returns one if there exists any such pair otherwise you need to return minus one this is what you need to do you got the problem no so like we need to return there is a chance if there is if there exist a pair which can be swapped right there exist some value a in array a and some value b in array b which can be swapped so that their sum becomes equal if that pair exists i'll return one otherwise i'll return minus one yes are you only using one swap on the ah you have to do one swap only okay okay so shall i stop sharing my screen sure okay now now i'm adding your screen right yeah okay you need to tell me the idea right what yes i'm like uh we'll be giving it two arrays um we'll be having some you have to swap only one element from the a to b such that the sensor will become equal so correct the the first thing i will be doing is i will be calculating the sum of the two arrows first like if we consider the sum as some some of the first arrow is s1 and the sum of the second secondary is the s2 so we'll be considering the greater sum first so we need to subtract this by 2 or could you please give me an example like that one for example okay you want to see the example once again yes sir one thing so it was like 4 1 the array was 4 1 2 1 1 2 4 1. 2 1 2 1 1 2 1 okay and array b was 3 6 3 3 3 6 3 3 and if you want to consider another example right here array is 5 7 4 6 8 4 6 and array b is 1 2 3 8. for this one two six six that's it fourteen so obviously the we need to make the sum of both of the arrays that submission that sum should be between 14 and 22 for sure yes so if i want i'll be considering the smaller number first i'll check if i can make 15 using 15 if i want to make 15 i need to borrow one from this one and uh not one i need to borrow seven if we now we cannot make that 15 okay so if you want to make 16 you crack two for this then we have don't we don't have two there if we want to make 17 we need to borrow three three is also not there if we we have to make 18 18 is possible for 17 tell me false for 17 do you really not need to worry three or you need to borrow at least four because one is already there the lowest number that is one is already there so you will be giving one right yes sir yes [Music] um instead of that after uh calculating the sums if i loop two arrays like if i exchange these two values five if i start these two values then the sum is going to be 22 minus 1 21 and 14 minus 5 9 so they're not equal again i will be checking 5 5 2 and 5 8 3 and 5 8 it is not yes sir like i will be having two loops like uh first in the i'll check five with the one two three eight i'll swap them and calculate the suns uh if they if if at any point of time the sums are equal then i'll be returning true or else i'll be written false so time complexity for this is going to be of n square won't work right the like is not going to work sir because n square is not expected right this this will give me the solution right but n square would be would not help me okay you want me to optimize itself yeah okay so [Music] so i'm looking this way if give going to be 23 then i need 13 if i give one to this array my sum will become 13 will become 23 so the difference is going to be 23 minus 13 is going to be 10 so i need to borrow 5 from this one so i think uh initially what i will be doing is i'll be maintaining a hash map so like for this one for this for the first array then i'll be looping over this array like uh i have one right so i'll try to share this one with the first array i'll give the one so if i am giving the one to the first array the sum will become 23 so my my current my second second sum will become 13 so the difference is going to be third 23 minus 13 it's going to be ten so in order to make those two equal i need to borrow five from it so that it will become eighteen and this will also become eighteen so i'll check whether if five is there or not as we have five i'll be written in true if it is not formed i will be going to the second number then i will do the same processor so the time complexity is going to be off and off and only as if we use unordered map and uh space complexity is also going to be of m so how it is going to be o of n right how can you tell me right for every element right you will first first find what what you will do 22 minus 5 right yes i like no sir like initially can you yes yes tell me the approach it is not going to be off and i'll go i'm going to maintain an answer okay and uh on the store all these values like to check whether the number is there or not okay so that loop is done so again i am going to in the the outer loop this is one loop this is another loop these are they are not necessary so here i will be looking through these elements so here i consider one so if i am giving one to the first array the sum will become 23 23 my sum will become 13. how it will become 23 right yes you will be swapping you will be swapping on the element now yes so there is one yes sir in the second step i am going to take that like it will become 13 so i need to borrow in order to make these two equal i need to make this one 18 and this one also 18 so i need to swap this five i'm thinking whether that five is existing or not there do you got my closer how will you get 18 how will you get 18 i'm not getting like uh like what i'm doing is i'll be giving one to the tariff initially i'm going to bring one to the terrain so it will become 23. so now i need uh i'll be calculating this difference of 23 and 13. it's going to be 10 10 yes so i need 5 so that they get balanced i need to remove 5 from this one and add 5 to this one okay so i'll check if whether the 5 is existing or not so as 5 is existing i'll stop this here and it will become 18 and this will become 23 or not 23 this will also become 18 13 plus 5 so in this way i'll be taking sir if it is i'll be looking through this array if at any point of time if i find the it is existing then i will be returning through or else i'll be letting it also but there might be a chance it might fail yes it won't work right dividing by two generally could you please give me answer okay so you can apply binary search to like you know that there would be some element in one array and i could look for another element i can apply the binary search on another array to find the element that i'm looking for yeah yes yes so previously what you were doing you were actually doing the linear search right which lead to the bigger n square complexity yes sir yes so if i consider one as a strap element then i need to search for 21 what element you have to search for that that is what you need to consider right for if it is one what element you are searching for if it is one then i need to search for it will become 21 and this one will become 15 21 minus 15 is going to be not uh everything one it will become 21 so this one will definitely become 15. so again i need to give one number two so that the both of them will be equal what number should i search for it yes what number should you search that you need to figure out [Music] 18 [Music] is going to be 19. if i'm giving you the 5 to this number it's going to be 19 it will become 18 to become 70 to become 19. so the number i need to search for the switch in the secondary is to be equal okay on getting any idea right what element should you be searching for no sir try to generalize this thing right if you can rather than going on these numbers try to generalize this thing in terms of x and y i that that would actually help you i can tell you oh plus y s two plus six minus right okay one let's leave this question right let's leave this question let's try to move to let's not play much more time on this right let's go for another question so you are given a binary search tree right yes you are given a binary tree right and you need to figure out whether it is a binary search tree or not what approach would you follow i need to check whether the given tree is binary solution or not yes so for a binary search tree if we perform the inorder traversal it's going to result in a sorted order set okay so although i'll be considering an array and i'll be performing the inorder traversal so for every like during performing the inaudible i'll be pushing the each element into the array then at the end i'll be checking the given array sorted or not so it's going to be what will be the complexity of this the space complexity is going to be of n uh the time is also going to be off answer what is n in this case the number of nodes no no no no no not often yeah it's so often and time complexity context is also yeah sure as you traverse as you only perform the inner traversal only it will be off and then for the checking whether the array is sorted or not it's going to be also often okay so i am given a binary tree right yes sir i need to find the vertical sum of binary tree vertical sampler can you do it yes sir for the vertical sum i'll be like if you have a tree what so this one the i need to print for the each level sir like yes yes yes so here the answer should be 3 1 and 13 and 4. okay [Music] so the root index is going to be zero if i go left it's going to be minus one minus two so what is minus one minus two like if we go left then the if we consider a number line if we go left it's going to be negative values measure if we go right if we go into the positive value so if we consider this root as zero then all the lines which are left to it going to be minus one minus two in such a way and uh okay i'm talking about vertical levels uh minus one minus okay so it is also same kind like i'll be traversing through the binary tree then during when i'm going to the left i'll be decrementing the level by vertical level by one and i'm going to the right i'll be incrementing the vector level by one then uh during the traversal i'll be updating the sum in that level as well okay i'll be considering a maths or in that map i'll be storing the sum for each level okay what will the complexity of the solution oh the answer it's going to be for traversal it's going to be of n where n denotes the number of nodes and for storing also it's going to be taking off and only if we construct the unordered map even though the first case time complexity is going to be off and square for unordered map if we consider ordered map it's going to be off and logging okay okay why would you need ordered map in this case like uh for the anode on map the time the worst case time from the xt is going to be offensive why would you why would you be needing an ordered map in this case yes is ordered map required like it depends on like depends on the output we want to print like if you want to bring the output in the order manner like uh if we consider this one if you want to print the minus two level this is a three level first then this is one per level then this eight five level then four level then we need to use order master otherwise we need to use another method okay fine fine okay which is your favorite programming language tell me c plus yes okay so i hope uh that's all from my side anything any any questions that you have for me no sir like however was my performance like is there anything we'll come to that we'll come to yes we'll come to that so now i would love to give the feedback right what we have would you love to listen to that yes okay so how did you felt when we started right yes somewhat nervous but thought um by solving the problems i felt comfortable sir okay and you do you know why did you get comfortable maybe i focused on solving rather than other uh people think what something like that because i i made you comfortable right i asked you those questions you knew the answer did you realize that yes because you have strong conceptual knowledge you have gone through the concepts right but the problem is if you're given a problem which you have not solved earlier right there are chances that you might stuck and you did actually you did because you were not expecting the questions from the projects right yes sir you were expecting the questions from dsa only so you would be asked some dsa questions that you would be solving and you were really uh prepared for that yes but when an unexpected that like those project questions came you you actually uh halted over there right because you you did not expected it to be there right and what i wanted to check is whether you can handle the unwanted situations or not because every time you would not be getting the situations which for which you are prepared for right that's why i started with the projects and you should be having when you are appearing for the interviews you should be thoroughly uh equipped with the knowledge of your projects like whatever you have mentioned you should be knowing right because the answer that you given about angular react was wrong absolutely wrong so it started with a very uh that exp that impression right that you have worked on different projects but you don't have knowledge of those projects so you have not i don't know i might be wrong but yes you didn't do the complete study right why you are choosing the man's check why didn't you go for means check right so you didn't do that simply you you were learning something the months check you implemented some certain project but you are not aware why you chose to use this this stack only yes sir right okay so that was like it's how it started so i asked you another question which was not a normal logical question right not normal conceptual question of data structures algorithms it was somewhat a molded question which you all might you might have encountered when you will be solving those code chef things and code forces things right there you there you are not ask the direct uh the algorithms or data success questions right but i rely when i realized that yes you can do it then i moved to some question which was a direct pre-question right yes just to figure out whether you know the concepts or not and when you were able to answer those by that binary search tree in one attempt right you did you because you knew the answer right and second the second question is also vertical sum direct question right just wanted to check whether you have done these things or not so basics are correct based you you're strong with the basics right but still need to practice a lot of questions dependent like which are based on those concepts yes right need to work on that [Music] okay so if i would have been the real interviewer definitely i would have asked you to get prepared and come once again like come another time right okay so all the best for one for your interview like for a future interviews and i hope you will do great and i hope you like the feedback like you find it genuine right you must work on it and would be cracking some very good companies in the future anything that you would love to share with us share with gfg yeah sir it was a great experience by user i have seen some other interviews which you got into which you interviewed with the students okay they were they're also great i feel so honored to be interviewed by you it was a great thank you thank you thank you thank you come on thank you very much so guys so bye bye bye bye boys let me talk to my audience okay so guys this was smurvan and it was really nice interacting with him okay and before leaving i would love to ask you right the same thing you need to type one thing that is i love gfg everyone everyone please type i love gfg before leaving the session and if gfg is of some use off for you it's like you have used gfg for some of the helps right you need to write i love gmg and after that we will be closing a session i love gfg everyone everyone please yes thank you versa thank you indrasis okay that's great everyone has to do it right still still not getting from everyone thanks shaker thanks learn coding thanks krilov thanks sahan okay that's what kind of love we are waiting for right everyone has to do it and finally i hope you all love the session you all love the problem that we discussed today okay new songs remix right do you want to ask anything if still you have any questions you can put you can drop your questions in the comment box you get it right you love gfg okay that's fine that's fine okay i hope you love the questions today and you love the interview yes if you want to attempt vivek if you want to appear for this interview the description would be there in the link right it would be there you can fill those for the form and you would be select if you selected you would be called for the interview over here best way to learn data structure is visit gfg practice on gfg right you would be able to do that you don't need my contact number put a request on linkedin i'll accept that i told you the worker best way to learn data structures is again visit gfg and explore gfg practice on gfg right how can i prepare for aptitude aptitude is like their certain resources that you can follow their certain books what matters in aptitude like you you would be able to find the correct answers but what matters in aptitude is uh your speed speed matters so when you are practicing aptitude you need to practice how much how more problems you can solve in one minute or the 10 minutes or 30 minutes of time right it's by push khandelwal linkedin id you will get push handle wall you search for fusion mentor at geeksforgeeks you will definitely get it okay so guys thank you thank you very much for giving your time and coming to the session and i promise you that you will be getting more and more sessions like this in future as well with this what we can say is bye byes