How To Pass Your Coding Interview: Technical Interview Problems Opinion..

 

In this video I'm going to be going over my four-step strategy on how I approach technical interview problems and in my opinion this has been the most effective strategy for me so stay tuned because we got a good one for you coming up huge shout out to the sponsor of the video jet brains academy technical interviews can be super stressful however with practice and the right tools you put yourself in a good position to succeed there's even an article about how a developer solely used Jet brains academy to learn python and prepare for interviews and landed a job as a software tester at Nokia the thing I love about this product is that it takes all the scattered knowledge across the internet and consolidates it into one Place you just pick a track you can pick python java KotLin and more the knowledge map shows you all the topics in that track and the connections between them Jet brains academy is a project-based learning platform and you can pick the difficulty of the project depending on your proficiency level as well as a personalized study plan which gives you things like question of the day and topics to review  based on what you've learned and need to learn there's also seamless ide integration so you can use the powerful features of jet brains ides finally you can upload your finished projects to git hub which you can add to your resume to showcase the various projects you've created so use this link right here to get your first month completely free and I'll also leave a Link down in the description all right before we start we need a game plan most people think that coding takes up most of the time in a data structures type question but it's often not the case so here are the four steps that I use one is to understand the problem a lot of times the interviewer will make the question vague on purpose so you can't even answer it without asking questions step two is diagramming out the problem this is where you actually without coding you just figure out the steps needed to solve the problem step three is writing out those steps basically the algorithm and step four is just translating those steps into code all right so let's use an example problem for this demo this problem is Called Two sum I'm sure a lot of you have seen it it's kind of a classic but basically you're given an array of Numbers and a target number and you need to figure out whether or not two numbers exist in the array that add up to the target number all right so we have a couple of examples here on the top we have an array of four elements with a target of ten if we look here we would see that two and eight would be our two elements that add up to ten so this would return true the second problem here uh we can't just use 12 because we need to use two numbers that add up so if we wanted to use 12 we would have to find a 0 somewhere however we do see that 6 as well as 6 add up to 12 so this would return true as well all right so let's talk about the first step which is really understanding the problem because there's no point in trying to solve it if you don't fully understand it now obviously we don't have an interviewer to ask so we're just going to have to make some assumptions but a few questions that you could ask are something like will there be negative numbers will everything be an integer or could we Have floating point numbers as well is the list sorted how many elements can there be can there be zero elements can there be a million Element  some of these questions might not even matter when you're solving the problem but it's still good that you're thinking about them and you'll probably think of more questions as you go on but that's totally fine the next step is to diagram out the solution now this part will probably take the most amount of time probably like 40 to 50 percent of the interview all right so let's take this first example here and kind of see how we can figure this out so initially what we could do is we could just test every combination here and check if it adds up to 10. so initially what we could do is have something like a double for loop where we have one pointer pointing at the two and another loop that loops through the rest of the elements so initially we would check two and seven that equals nine so that's not True we check two and fifteen again that's not true here we see that we actually get to two and eight that equals ten then we return it true so we found the solution pretty quickly but we would potentially be having to go through every combination which would give us a time complexity of big o of n squared we're not using any extra memory so this is going to be a space complexity of a constant now I did mention that this is like a brute force solution so it's pretty slow however I still think even if you initially think of something better it's still good to start out with the brute force approach because it's usually going to be the easiest solution and oftentimes that's kind of what companies are looking for like a lot of companies they want to push out their product as soon as possible and a lot of times engineers try to over engineer certain things but oftentimes it's important just to like get a solution out there and then you can iterate and improve on it later on so this is a good thing to mention to your interviewer you know mention the brute force approach and then ask them is this acceptable or do you want me to optimize and this is another reason why it's better to diagram your problem first than to just jump into the code because maybe your interviewer wasn't really looking for a solution like this then you just wasted a bunch of time coding it up so we'll assume that the interviewer wants something a little bit more optimized so another strategy we can do is we can say okay we're going to start at the two we're still going to loop through the array when we get to 2 we know that we need to have an 8 somewhere in here in order to get to our target of 10. so we can use additional memory to keep track of what we've already seen so what we could do here is we could use a set and say okay we have a 2 here we know that we need to see an 8 at some Point so what we do is we could just save that here in this set then we move to the next element we get to 7 we say ok we know we need a 3 to get to a 10. is there a 3 anywhere in this set no there's not but there might be later on so we want to just be able to save That then we go to the next element we're at a 15 we know we'll have we would have had to see a negative five at some point have we seen the negative five we check our set no we haven't so we go ahead and add that to our set we move our pointer to eight we say okay in our set are we looking for an eight well yes we are because we have one right here that means that we have a pair that equals our target of 10 and then we would return true if we had gotten to the end of the array without finding anything we know that there is no pair that adds up to 10 and we would return a false the reason we're using a set instead of a list is every time we would want to have checked this list here we would have to iterate through every number and check to find our target number however since we are using a set we're able to index directly into it and that saves us the time of iterating through the list so what's the time and space complexity here well we are only going through our List one time so that's going to be big o of N and since indexing into the list is constant time that doesn't affect our time complexity however we do have to account that we are using this set here in memory so our space complexity will be o of n because of the size of the set could be the size of our initial list all right so now that we have a diagrammed out solution we want to write down the steps and this is such an important step because if you just jump into the code at this point your interviewer might not really know what you're doing and that's the last thing you want to do is to lose your interviewer because you're probably going to get docked for that but showing the steps and this could just be in clear English ensures that you and their interviewer are on the same page alright so what are the steps that we need here we want to loop through every number in our array if our set contains that number we return true otherwise we add the complement to our set and the complement is just going to be the target minus the number if we reach the end of our array we know that we haven't found any two numbers that add up to our Target and we return false all right so we're almost there the last step is just to take those steps that we wrote and just convert it to code so I'm going to be doing this in java but it should not look too different in other languages so here we have a function that returns a Boolean we're going to call it two sum we have our input which is an Array of numbers and then we have our target which is an integer so the first thing we want to do is create our set next we want to loop through every number in our array now if our set contains that number we return true if it doesn't then we want to add the Complement to our set finally if we've broken out of our for loop and we haven't found anything we return false alright so at this point we have a working solution in code now at this point it's up to the interviewer and what direction they want to go but often they'll talk about testing what kind of input can we put in that could potentially break this algorithm so you're going to want to be thinking Of things like okay what if does it work with an empty list or a list of one Element is this going to work with negative numbers is it going to work with a list of duplicate numbers let's try it with a list that returns false unless that returns true just any type of like edge cases that you can think of all right so there you have it my four-step strategy to ace your next technical interview and as you can see the coding aspect of it was really just a small portion once we diagrammed out our solution wrote down the steps that we needed it was really just a matter of translating those steps into code so hopefully you guys learned a lot from the video if you did make sure you hit the like button make sure you subscribe if you want to talk more about this feel free to join the keep on coding discord server where you can connect with other Developers it's totally free link to that down in the description thank you guys so much and as always keep on coding so stay tuned because we got a good one for you