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Oh actually?! How’d you handle the case where you have more than one instance of an element in the current window then?

@@alejandroill i removed the element until i could add the current one again. example: [1,5,4,2,9,9,9] once i'm at [4,2,9] then the next element is also 9, so I remove 4, then 2, then 9, and then add 9 (a loop that checks for this) ''' while nums[end] in unique or end - start + 1 > k: unique.remove(nums[start]) cur_sum -= nums[start] start += 1 '''

@bogus3007 Ah I see, you preemptively delete even more elements when you encounter duplicates, that’s pretty smart!! Way to go man! 👊

Ayyy thank you broski, I was just too lazy after the mental toll yesterdays problem took on me 🫠 Pinning this comment for everyone to see 😎

Thanks 🙏

Hey, thank you so much for subscribing!! In my opinion, Java is a great language to code DSA with, and the one that I started with myself :) In the end I did end up switching to Python, just because it allows me to think more about the problem instead of language specifics. I.e. if you don't know any languages, then Python is probably best way to go, but otherwise the best language is the one you're most comfortable with! As long as you learn basic things such as creating & using certain data structures like HashSet<T> class and etc, you'll be totally fine :) If you do want to try out Python however, one of the best videos I've ever watched regarding the things you need to know about Python for Leetcoding is the following: ruclips.net/video/0K_eZGS5NsU/видео.htmlsi=COwJt0uhRDs4Vb2c Let me know what you decide, and remember the most important step is to start!! Don't dwell too much about which language to use, that matters much less, and if you want to stick to Java that's an absolutely perfect choice :) I'll be looking forward to seeing how your journey goes!! 😁

@@alejandroill Thanks for your reply bro 🛐 And I don't have any idea about python so I am continuing my journey with java Thanks for help 🙏

Of course, and Java is a fantastic choice!! What matters the most is that you start 😇 Feel free to keep me updated on how the journey goes as you go along, I’d love to keep hearing from you!! Best of luck brother ❤️

Haha that’s always the worst 🫠 Although usually in those cases I feel either (1) you’re really close and just missing a few edge cases or (2) you tried a greedy solution that is not correct for all edge cases. Did you figure it out in the end??

Haha yeah, at least we got it!! And wdym by lower & upper bound? 🤔

@alejandroill So my intuition was i do 2 Binary Searches to get a range and add that to result. The first is the lower bound, second is the upper bound. Example when num is 4 with lower 5, upper 10. The lower bound would be 1 and the upper bound would be 6. We try to search those in our array and add the range if it's available.

@notbalding Ah I see, do you have to make this call for every number in nums then? And for each then find the range, do (j-i+1)(j-i+2)/2 and subtract 1 from each numerator product in case num itself is in range? That’s a super cool solution!

@@alejandroill Yea a call gets made for every num, could add a memo but i doubt that it's worth it. BS is most likely faster than hashmap lookup. I'll just add part of the source code. the predicates are so you find the left or right most duplicate incase there are. ```cs int lower_target = lower - nums[i]; int upper_target = upper - nums[i]; int lower_bound = Search(nums, lower_target, x => x < lower_target, x => x >= lower_target); int upper_bound = Search(nums, upper_target, x => x <= upper_target, x => x <= upper_target); if (lower_bound == -1) continue; lower_bound = Math.Max(lower_bound, i + 1); if (lower_bound > upper_bound) continue; output += upper_bound - lower_bound + 1; ``` can paste it in discord if you like some color.

Ah that’s smart, and haha I forgot you code in C#! That’s actually super cool 😁

Ayyyyy welcome back!! 🥳

:)

Haha yeah! I think it helps that I’ve coincidentally been solving a bunch of binary search problems from the Neetcode 150 lately, so I was able to almost instantly-recognize it 😅 Thinking of things as potentially sorteded array of booleans helps a lot!!

Haha thank you! Greedy stays ahead 😎

This is the order that was recommended to me by a friend of mine when I started my Leetcode journey 2 years ago, and even by Neetcode himself I believe (before creating his Roadmap and etc.) Doing it by problem difficulty has a few advantages, and in fact there’s a medium article that explains it better than I can 😅: “”” I want to reiterate again that what you choose is up to you, but I would highly recommend doing them in order of difficulty. The reason for this is that it will ease you into the list better than doing it topic by topic. If you start by completing one topic at a time, then you will be doing hard questions from the start which can put off your tempo. Additionally the hard question require more time and knowledge so you might feel discouraged slowing down for them earlier on, but once you have the foundation of doing all the medium and easy questions in the list, they are much more manageable. Doing the list by topic also means that you won’t see topics again for the rest of the 150, depriving you of the chance to revise them. Reiterating on previously done topics to solidify your knowledge of them is critical in the learning process, which you won’t be doing as much if you do the list in order of topic. So, to sum up this section, I highly recommend doing the NeetCode 150 in order of difficulty and not in order of topic. “”” Article Link: medium.com/@theconnoisseur/how-you-should-approach-the-neetcode-150-a-kickstart-guide-b88b59819108

@alejandroill thanks for the info! I'll try it out.

Awesome!! 👏

Hahaha yesss 😇

That’s exactly right! I wish I realized that while I was solving it :(

Hahaha, and darn I didn’t even think of going bit shifts!! I just treated them all as strings via bin(…) function 😋😅 I love getting to see your comment everyday, thank you for doing this ☺️ (gets a little lonely sometimes… 🫠)

bro if youre 14 and doing DSA it doesnt matter what you use.. but id recommend python for interviewing, maybe projects in C could be cool

@@bogus3007 Thanks a lot man:)

(I’m cooking up a response, just might be a minute since it’s a long one!) Edit: My reply is too large to fit in a single comment, so I’ll split it across two comments here below 👇

Hey Ashu, first of all I want to congratulate you for starting so young at 14 years old, that’s absolutely incredible!! 🥳 A lot of my friends, myself included, really wished we started programming before going to University for Computer Science. You’re already ahead of the curb!! As for your question, it’s rather simple to answer, but depends majorly on what your goals are. I’ll start off with the pros and cons of C and Python, since you seem mostly focused on these two. As a fair warning, these two languages could not be more opposite from each other: Firstly, I'll highlight the difference between low vs high level languages, as C is a low-level language, whereas Python is a high-level language. A computer at the end of the day, only understands electricity: electricity "on", and electricity "off". We use transistors and logical gates to simulate logic, but essentially computers are able to use this on/off state of electricity to be able to understand binary: 0s and 1s, where '0' means electricity off, and '1' means electricity on. As humans, we cannot think in terms of 0s and 1s like computers can, so we develop languages that we do understand, and then take time to translate them into 0s and 1s so that the computer itself can understand them. So coding in 0s and 1s, which no one really does, would be the "lowest level" form of programming. Above that there is assembly, which humans can understand and write in, which then will be translated into an equivalent program in 0s and 1s once finished. Above assembly there is C, where when you write a C program, you will need to "compile" (translate) it into an assembly program, which will then be translated into 0s and 1s via opcode instructions, which the computer can finally understand and run for you. As you can imagine, the higher level a language is, usually the easier it is to write in, but the more costly and slow it becomes due to those translation steps that are needed to convert into 0s and 1s. Python is an interpreted language which is a little different (translates the code line by line instead of all at once to be ran as an assembly file like C), but for now you can think of it as Python needing to be translated into C code, that needs to be translated into assembly code, that needs to be translated into 0s and 1s. In principle: The higher the level of a language, the easier it is to code in for the developer, but at the cost of loss-in-performance. C is a very low-level language, whereas Python is a very high-level language. Now as for which I'd recommend between the two: C: C is again a low-level language, that I'd recommend mostly if you're looking to become as prepared as possible for Computer Science in University. Since C is low-level, proficiency in C will require you to deeply understand how memory works inside the computer, how pointers work, ensuring you collect your own "garbage" (free-up memory by your own volition instead of having it handled for you), and more. It is also the language I recommend if your goal is to enter a profession such as ethical hacking or systems programming, where the more low-level experience and understanding of how computers work under-the-hood, the better. If you understand C it will not be too difficult to learn C++, which is still fast enough (especially compared to languages like Python) to be used in the worlds most high-frequency environments, such as Quant Firms where every millisecond of juice in throughput you can get highly matters. Python: Python is again a high-level language, whereas maybe not as performant as C, provides a much friendlier developer experience. I'd recommend Python if its your first programming language, or you want to begin building cool stuff such as via rasberry pis, games with PyGame, your own scripts for personal purposes or automation, or even data science / backend development for internships using frameworks like Flask or Django for backend development, Numpy & Pandas for data science work including Pytorch or Tensorflow for machine learning, etc etc. Just in the world of internships, if you could ONLY pick between Python and C, Python would definitely be the way to go in my honest opinion. It is also my recommended language of choice if its your first programming language. It is a very flexible and versatile language for many things, and since many things in life don't require the utmost amount of juiceable performance as humanely possible out of a computer, it turns out Python is rather excellent for many use cases in the software development world. Also, if your goal is to become proficient in DSA & Leetcoding, it depends on your goals, but if its for maximizing learning outcomes I bet you can probably guess my answer -- but I'd recommend python as it just helps save on a LOT of the thinking for you, but I will admit that a great majority of competitive programmers leverage C++ for even better performance. Now as for my two cents, if you're 14 and looking to learn programming, have some fun with it, dwelve into a bunch of topics and see what you like, then without a doubt I would recommend Python. It really depends on what motivates you as a person, though if you are very internship-motivated, then it's a slightly different story. Personally, if I was starting over absolutely from scratch with zero knowledge about programming, I'd recommend a roadmap like this: (1) If you have absolutely no knowledge of programming (which I don't think is your case!), then I'd start off very small and go through this video in full: ruclips.net/video/rfscVS0vtbw/видео.htmlsi=jtrA8g4M-xdaoWKB. I love Mike Dane, and this is the exact resource that I used to teach myself the basics of programming in Python before my very first programming course in University 😊 (2) Second, once you have at least some familiarity with programming, i.e. you understand control flow via if statements, for & while loops, etc., then in my opinion there is absolutely no better place to learn than Harvard's CS50 course. I watched this course on my own for fun, and the first half is an almost near-exact replica of the CSCA48 course that I took at the University of Toronto (where I studied). The second half of CSCA48 focused even harder into elementary computer science knowledge, whereas the second half of CS50 focuses on learning how to build stuff, learning SQL, python, javascript, development work, and etc -- which I think even fits better with your goals!! I mainly LOVE this course because it does start off with C (after Scratch), teaches you the core foundations of how memory works with computers, pointers, easing into storing memory via arrays, realizing their limitations, introducing you into linked lists, then seeing those limitations, into then BSTs, and only then once you have the absolute fundamentals down -- going into the world of developing cool stuff with software 🙂 If you're interested, here is a link to a playlist of all the lectures for you to watch & learn from: ruclips.net/p/PLhQjrBD2T382_R182iC2gNZI9HzWFMC_8&si=DkMuPloW2Ya3JP6p. I HIGHLY HIGHLY HIGHLY recommend this resource, especially since you're 14 and starting out into the Computer Science world, having this foundational knowledge of programming & computers is an UNBELIEVABLE advantage at your age, especially if you're looking to go into Computer Science for University, and build a foundation for coding to build off of before starting to work on projects and entering the internship/job world.

(3) At this point, assuming you've gone through CS50, you have access to the knowledge I had (and more!) as when I just finished my 1st year of Computer Science at the University of Toronto (and about to go into my 2nd year). This is the time where I recommend you can go into the project-building world, starting maybe with a niche that you'd like to explore. I will say some niches might be harder than others, i.e. learning game development with Unreal framework in C++ might be more challenging than learning about front-end web development with a framework like React. At this phase, you have many options. You can go into the web development world, for which I would ABSOLUTELY RECOMMEND the course by Dr. Angela Yu titled "The Complete 2024 Web Development Bootcamp" on Udemy. It's not free and you'll have to pay a bit of money, but if you're willing to do so, make sure you wait for a sale on Udemy as they happen OFTEN and you can usually snatch up the course for <$20 instead of the default price it's listed at (which is usually >$100). It was the resource I used to learn web development from scratch, and boy can I say one of the greatest investments in myself that I have ever made. Dr. Angela Yu is a FANTASTIC teacher, and also has more courses that I've never tried (but I'm sure are also excellent), such as a 100 days of Python course! If you do go through this web development route and realize that you absolutely love it, and especially on the React side of things (which was one of my favourite parts of the course), I'd recommend a followup course such as "React - The Complete Guide 2024 (incl. Next.js, Redux) by Maximillian Schwarzmuller also on Udemy. If web isn't really your thing, another area is mobile development! What's nice is that if you did do a course like the Dr. Angela Yu Web Development one above, that you'll have some good practice and knowledge around React, so you can already get your hands down and dirty with something like React Native, which allows for cross-platform development. If you're not sure what that means, that's okay, essentially there's two main phone operating systems used nowadays: iOS and Android. If you want to purely learn iOS development, which I believe does require you to own a macBook, you can do so via Xcode in the Swift language, in fact Dr. Angela Yu's expertise is in iOS development (not web development!) and has a course on it as well up on Udemy! Otherwise you could learn something like Android mobile development via Android Studio in Java (or Kotlin nowadays), or a third option which is cross-platform development: these apps will always be slower than their native counterparts (i.e. an app designed for Android coded in Kotlin / an app designed for iOS coded in Swift), but have the advantage that it can be used in either phone operating system and app store. For cross platform development there are many options, including Flutter, but one of which again is React Native, which will translate on over very nicely if you now have that Web Development experience in React from Dr. Angela Yu 😁 Otherwise there are many other fields you can go into as well, such as game development, cloud computing (like me!), but in my opinion either Web or Mobile Development is probably one of the best ways for a beginner to get their foot-in-the-door into the software industry, so especially for you if you have the goal of landing internships, I think they can be a very solid and foundational choice. I would definitely still recommend starting with something like CS50 at the start to build some of that foundational knowledge, it's like learning how to shoot a free-throw or a layup in basketball before getting to the cool stuff like learning how to dunk or make fade-away shots haha 😋 The important part is to start developing projects, as with these you can not only have a lot of fun, but a lot of learning, and also things to start showcasing on your resume for employers to see as you begin applying for internships. You have a long road ahead of you, and if there's anything you take away from this, it's be curious and just keep trying new things! Some of the smartest, most talented developers I've met throughout my college years were because they started when they were younger, particularly in things such as building games in Roblox with Lua, since they liked to play Roblox as kids! No matter what you do, I'm sure you'll be absolutely incredible, I myself sure wish I chose to learn a little bit about coding when I was just 14 years old! You've got this Ashu, I hope my advice comes in useful to you in any way, shape, or form, and I really just want to applaud you for starting so early 👏 I'll be looking forward to how your journey progresses, I'd love to watch you grow as time progresses, so be sure to keep me updated!! Best of luck to you ❤️

Ahhhh that’s really smart, I was trying to come up with a way to do what I was doing but whilst modifying the array to make it go even faster. Bubble sort is unironically perfect here 😂 And wdym grouping by set bit, could you clarify? 🤔 I suppose you could split the array by set bit groups, then check if they’re each sorted? Or wait if they’re all same bit in a group, then 100% you “can” sort it. So then you just have to make sure that the max of this group is less-than-or-equal to min of next group? Or wait, then you just need to get min & max of every group, which you can all do with a singular O(n) parse… DUDE YOU’RE A GENIUS!! I’m literally on the bus on my way home right now, you just made me realize how to do it in O(n) time 🤯 I’ll have to try and see if that works at home, but if so they definitely should have upped the constraints on the problem! That’s an EXTREMELY clever solution, thank you so much for sharing it 🥰 I’ll pin this again for everyone to see!!

Noooooo, don’t give up!! I think I get what you mean, the pinned comment actually made me realize how to solve this in O(n) time as I was reading it 😅 Were you able to solve it using an O(n^2) approach?! One way I realize now is to just do bubble sort, and at any point if you’re not able to perform a needed operation (I.e. set bit counts are unequal between two numbers you need to swap), then return False. Otherwise, you were able to sort the array, hence return True :)

Yes! Until I realise that it’s simpler than I thought!

@deerajthakkilapati1030 yeah bro it happens😅

Haha, I was also surprised when the simple-approach solution actually worked :p After the fact, it makes sense though!!

Hahaha exactly 😂

Hahaha, what did the hint say?? And aww it makes me so happy to hear that, I’ll be looking forward to reading your comment every video 🥰

​@@alejandroill The hint said to think in the smallest possible even integer ps. my name is also Alejandro.

Ahh I see, yeah that definitely helps 😋 And no way, where are you from if I may ask?? I know I have a Spanish name, but I’m actually from France… 😅

Thank you so much!! 🤗

OSMANYYYYYYYY!!! What’s up my man?! Nice Enrique Iglesias reference 👨 But don’t think for a minute this means you’ll get to skip tomorrows daily with me, I got my eye on you sir 🤨🫵

🤘🏻😎🤘🏻

Thank you so much!! 😊

Ahhh checking the string lengths first is definitely super smart 😂 Concatenating s against itself first is super clever!! I wonder if you get any time complexity benefit by leveraging the problem of finding out if a string is substring of another. I suppose you could sliding window efficiently to find all strings that are permutations inside the larger string, and only check those, but still O(n)… 🤔 Even if it’s O(n) though, that solution is definitely far better than mine!! Thank you so much for sharing, I’ll pin your comment for others to see as well!! 🤗

Thank you so much!! I’ll keep the videos coming 😊

Hahaha I was debating whether I should keep going or not in my mind 😂 Now at the party… everyone is arriving late 🫠

@@alejandroill😂

Hahahaha :p

Thank you!! 😊

Aww thank you so much! That really means a lot to me! 🥺 I’ll keep on going with you!! Are you currently preparing for technical interviews, or doing this out of fun / sharpening your skills? I’d love to know 😁

@@alejandroill I'm graduating this December and currently in technical interview prep. I wasn't always consistent with daily practice, but then I randomly came across you on my feed-it felt like perfect timing! Now, I've started doing it in parallel to keep myself on track.

Oh no way, that’s amazing to hear!! It felt SOOOOOOOOOO amazing to FINALLY graduate from University, I’m sure it’ll feel equally amazing for you!! 😂 Huge congratulations for making it to the end of your degree!! 🥳👏 And yes!! Feel free not only to use my channel to have a buddy to code alongside daily with Leetcode, but also chatting or leaving questions down in the comments like you are now!! I will always make sure to respond to every single comment while I can on this channel, that’s a promise 🤗 In my opinion consistency is key, and the secret to success for many things in life - Leetcode included!! If you’re able to solve problems alongside me on daily, weekly, or even monthly basis for a prolonged period of time, I have no doubt that the two of us together will become absolute BEASTS of Leetcode 😎 Let me know how the journey goes, and I’ll be looking forward to hearing from you in my next videos from time to time :)

Yooooo thank you!! 😎🔥🔥

My pleasure! 😇

Hahaha, so there was a way to solve this with a Trie?! How did you do it, is it more efficient?

Thank you so much, and definitely agree :) Understanding the solution <<< discovering the solution for learning outcomes!

🥰

Thank you so much!! It makes me so happy to hear that ☺️ I’ll keep the videos coming your way every single day 😁

Thank you so much!! ☺️ I can’t believe I’m already in 3 digits category, it feels just like yesterday that I started this challenge!!

Hahaha thank you :)

Hahaha yeah, I saw constraint of max 3000 and immediately knew n^2 would work :p Usually in the contests I’ve noticed that for Q2, you rarely have to bother making it efficient - but for Q3 (and esp Q4) you always do. The O(n) way I suppose would be start with starting index i, find smallest index j where (i,j) substring is valid, add length of string - j to result, increment i, increment j as much as you need to, repeat and end up with O(n)? I.e. sliding window and/or two pointers kind of idea? Curious what you did :-) Oooh I’ve never heard of “sieve of eratosthenes” before, I see it’s used to find list of prime numbers up to a certain limit… I’m gonna watch Khan Academy’s video on it right now, seems like a cool little trick to have under my belt 😊 I didn’t realize until after the problem that all numbers are either prime or divisible by prime (except 1), so definitely makes sense why this works to me now 😅 That’s a really clever solution, I appreciate you for sharing it! You seem to be very mathematically mature, how long have you been solving Leetcode problems if I may ask? Do you do it for fun, or for a specific goal you’re working towards?

​@@alejandroill​@alejandroill Yeah I did q2 the same way you mentioned. Yes, sieve is a pretty handful and well known technique to find prime numbers/factors quickly, it is quite frequent in cp contests, so I know. I have been doing LC for over a year and I am currently 2070. Hoping to reach guardian. 😅 I would suggest you to also try codeforces or atcoder contests at least the beginner ones. Would help you to improve a lot faster on LC contests imo. 😊

I just watched the video on how it’s implemented - I’m shocked at how simple it actually is 😅 These are the cool tips & tricks that I love learning on the way as I go through this Leetcode journey :) AND DAAAAAAAAANG, you’re cracked dude!! I gotta get my way over to knight first haha 😂😅 I’ll definitely have to check out code forces as well, if I can convince my friend Noor to do it with me then sign me up 😎 It’s always a good motivator to compete with a friend, especially when they’re better than you 😂 (not salty at all… 🫠)

Omggggg, that’s super clever!! Basically you’re always solving/simplifying the inner-most expression, so you don’t have to worry about nested expressions with more commas messing you up!! I didn’t think of that, that’s a really cool solution :)

Yooooo thank you so much! To be fair it’s kinda lucky I earned it, the solution was literally just brute force + caching… 😂

Thank you so much!! I’ll keep them coming your way 😊

Haha that was just me having a little bit of fun 😅 I’m from France actually :) And ahhhhhh I just checked again, the number is up to 10^8 not the number of digits, so it’s at most 9 digits. Does that mean you’re able to just get away with trying to swap every two pairs of numbers and returning the biggest result? 😂

@@alejandroill haha, that's what I did after I got annoyed by the use cases.

@notbalding Hahaha I might have done the same if I looked at the constraints more closely 😆 If they wanted to force O(n) all they had to do was make input a string, so in my opinion this was fair game 😎

@@alejandroill yea I agree, the weird part is they have done it for other problems and some are marked as easy. Just tells you how consistent they are with rating their problems.

Haha yeah, Leetcode problem difficulties aren’t always the most accurate… 🫠