Concatenation of Array - Leetcode 1929 - Python

hey everyone welcome back and let's write some more neat code today so today let's solve the problem concatenation of array we're given an integer array nums of length n so maybe something like this where the length is obviously three values we want to return a concatenation of this array meaning we take this array and then append it to itself so then the output array would be the original array plus the array again so basically adding each of these values to the end of the array so one two one so we have two copies of this array combined into a single array and that's what we want to return now there are many ways to solve this problem the easiest way probably would be to just iterate through every value in the input array so go here here here and then take each of those values and just append it to the original array so we can take the input array and then use that as the result and then return that so we would take the first one add it to the end take two add it to the end take one and add it to the end there you go there's the array and that's what we would return another approach would be to actually create an output array initially it would be empty I'm just drawing it this way because I know this is how much space it's going to take but initially it would be empty we take each value and append it to the array so one two one and in this case we want a concatenation so we would do this once and then we'd do it twice so now we'd add one to one if this problem was not asking for a concatenation and it was actually asking for maybe three concatenations then we would just do this same operation another time so this is kind of a more extensible way to solve this problem because we might want to concatenate a variable number of times times and the important thing to note is that since this is like a dynamic array and we're taking each value and just pushing it to the end each time we push a value it's going to be o of one time and we're going to do so n plus n times because the input array is of size n and we're basically creating a concatenation of it so we're doing that with this array twice but that's still going to be Big O of n that's why I think doing it this way isn't really bad because the time complexity is the same we are technically needing extra memory complexity if you count the result as needing additional memory if you don't count it I guess we're doing this in constant memory but now let's go ahead and code up this approach okay so we're going to create our result I'm going to call it ants for answer because that's what they were kind of using in the description of this problem and then what we want to do is take every number in nums and append it to the answer so just like this this we want to do that with every value in the input array how many times do we want to do this we want to do it twice so why not just wrap this function or this Loop in an outer loop which will execute let's say two times and then we pretty much have the result and we can return the answer what I like about this solution is it's generic like what if the interviewer asks you now write code that will do this three times or four times or concatenate five times or maybe there's a second variable given called X or you know something that will tell us how many times we want to do this so we can put X over here and then our solution would basically satisfy that now probably your interviewer won't ask you this but I think this is good food for thought so now let's just take this code and run it to make sure that it works and as you can see yes it does and it's pretty efficient if this was helpful please like And subscribe if you're preparing for coding interviews check out neat code.io it has a ton of free resources to help you prepare thanks for watching and hopefully I'll see you pretty soon