How To Solve Algorithms - Two Sum

[@mysterbirdtrooper6516]

I would love to see more of these. It's a nice addition to your other types of videos.

[@WebDevSimplified]

Thanks. I definitely plan to continue with this series.

[@neliyagurung4584]

@@WebDevSimplified u stopped making these

[@kran399]

@@WebDevSimplified They why Stopped making this Series. your broken your Promise 🙄

[@thedude142]

Almost every time im looking up a programming concept on here, without fail, i find you covering it. Thank you for all you do 🤙

[@WebDevSimplified]

Thanks for watching! If you enjoyed the video please let me know, because I would love to make more videos about algorithms. Also, don't forget to tryout the algorithm yourself on LeetCode, and view my code from this video on my GitHub. LeetCode: leetcode.com/problems/two-sum/ GitHub: github.com/WebDevSimplified/JavaScript-Algorithms/tree/master/Two%20Sum

[@MrVolkodaff]

This is just a great explanation, algorithms are still a weakness in my code. Thanks for the explanation, Kyle. Enjoy your videos, man.

[@RakeshKumar-vg7uv]

Video is short and simple but powerful. Thank you so much for making your videos short and always straight to the point

[@erinrose5794]

I would love more algorithm videos! I'm fairly new to coding and this is really helpful for prepping for interviews

[@skafaced102]

I've been using "Cracking the Coding Interview" (although dense, this is a great book to have) and ZTF Master the Coding Interview: Data Structures + Algorithms on Udemy! The udemy course is great because the instructor breaks big O and fundamental algos down for you as well as how to approach each data structure. However I use Web Dev Simplified all the time! He knows how to explain useful tools quickly and efficiently. Thought I would at least share some additional resources I've felt helpful for me as I prepare for interviews.

[@Train3816]

Please keep making videos! I’ve been binge watching your channel every chance I get. I’ve truly learned so much, thank you!

[@georgemccaddeniii8963]

Thank you for this video, Kyle. I'm preparing for some big interviews and I wanted to see this problem white boarded and coded out. You helped me really understand this approach and now I'll build upon this knowledge when working through others like it.

[@WebDevSimplified]

I'm really glad I could help

[@itsyourronit]

I really enjoyed it, no jargons, nothing that already makes someone feel sick, everything so simplified, I love this channel and the way Kyle tells stuff! It goes directly inside of my brain and resides there permanently

[@jasper5016]

OMG, Can you believe that I was looking for the exact problem? Thanks a lot

[@miw879]

I was struggling from one tutorial to another with there complex code, but I swear to god I'm not even lying when I found your video first I smiled because I was already damn sure that now I'm gonna understand it for sure because there is no questioning YOU ARE THE BEST TEACHER. I instantly knew I'm gonna get this now go my notebook up wrote with you and now I fully understand it..... From the bottom of my heart, THANK YOU VERY MUCH ❤ Please upload more algorithms from leetcode!

[@bartekfigatowski7980]

I liked it, more algorithms, please😁👍🙏

[@WebDevSimplified]

Will do!

[@loljakkon]

thanks man you explained this so well, I was able to find the solution after making my own long if statement nightmare and i couldnt understand that second solution when i was first looking at it, i didnt realize how they were saving into that object variable originally

[@veremox]

omg man, that way of doing this challenge is mind blowing! i am new to js and god, i've learned a lot just by watching it, interpreting the algorithm and then redoing it by myself!! very awesome!!!! this way of storing past values on a object like its a mapped bucket of information is incredible! opened a lot of doors in my head :O thanks! =)

[@zecosta9579]

Great tutorial, I think a series of this would be well received

[@WebDevSimplified]

Thanks. Based on how well received this video has been a series is highly likely.

[@zecosta9579]

@@WebDevSimplified That's awesome!

[@NirajKumar-bi5vo]

Enjoyed your algorithm videos. Keep making more of such videos

[@alicenyw1872]

I loved this! I never had to use algorithms before, but the job market seems to be more competitive right now, so I am encountering algorithms during interviews.

[@crestmarinaris6113]

This is super insightful. =) No other channel goes through algorithm and challenged so elegantly. Thank you for the video. Would love to see more of these.

[@WebDevSimplified]

Thanks. I am already planning out the next video.

[@PATRICKCHUAD]

very fast algorithm. Thanks for sharing. is the complexity of this algorithm equal to O(n) since there is only 1 loop ? O(n) is linear ?

[@chips-n-salsa]

thank you for making this....just starting on algos so this is super helpful!

[@mahrig1829]

Agree with other comments. Very happy to see these kind of videos (more advanced Javascript, problem solving, algorithms). Another great video!

[@WebDevSimplified]

Thanks. I plan to make more videos like this of all difficulty levels.

[@adriandeaconu5468]

Mate, I love your videos, you are very talented, keep up the good work. Like honestly, I watch plenty of channels just to stay in touch with different programming languages, but for some reason, you got me hooked up.

[@WebDevSimplified]

Thank you! I really appreciate it.

[@baefaux]

I've been teaching myself to code with JS and I actually understood what you were explaining! I can't wait till I write a program that I can implement this in!

[@pandat2473]

Need more content like this sir😭💖 This is really good please make some more videos like this Love from India 💗💗

[@abdulmayeedchowdhury1397]

Loved the way you described it. Thanks.

[@elva329]

Enjoyed your videos very much. Could you please continue your algorithms series if possible? Thank you

[@shisamo]

finally found a good explanation of two sum. Thanks a lot

[@bac9982]

Stellar video. Even as a Python guy you make the concepts easy to understand and the whiteboard breakdown was great. Thanks for making the time to make these and for sharing the knowledge with the world!

[@upmate2726]

Nice one. Thank you for a comprehensive explanation

[@shelbyrothman4522]

Everything you do is gold!

[@abhijeetgupta2754]

One of the best youtube channel for learning good stuff and I would like to see more videos like this.

[@WebDevSimplified]

Thanks. My next video will be another algorithms video. I hope you enjoy it.

[@caiquevallim2209]

Which book would u recomend sir? :) I'm senior dev and now I'm going to focus on learning fatests solutions to solve problems and in order to improve my skills

[@jaimemontesdeoca7989]

As always, a very helpful video. Thank you Kyle!

[@esportsnexus]

Awesome! Please make some leetcode series of medium & hard problems!

[@vladimirmikulic7860]

Please do more of this Algorithms type of videos. Great explanation BTW.

[@WebDevSimplified]

Thanks! Did the white board explanation help with your understanding or would you prefer more of just coding?

[@vladimirmikulic7860]

@@WebDevSimplified The whiteboard explanation was brilliant, I would love to see you explaining algorithm videos on a whiteboard. For me personally, it's easier to understand and it feels like a real interview :)

[@WebDevSimplified]

@@vladimirmikulic7860 thanks for the feedback. I was really hoping the white board would be beneficial, because that is the kind of content I find most useful. I'll make sure to keep the white board in future videos. Hopefully I can even upgrade to a whiteboard I dont have to hold.

[@vladimirmikulic7860]

@@WebDevSimplified No need to thank me, thank you! I really appreciate the effort that you put in these videos.

[@trangnusi13]

Thank you! Please make more videos like this. You are really helpful!

[@BluePhoenixGames1]

Great video! More videos about algorithms from you would be really appreciated

[@WebDevSimplified]

Will do!

[@oop_web7707]

Thank you for the video. If you can, please do more algorithms.I'm new in JS and I really want to understanding this part. Thank you in advance

[@WebDevSimplified]

My video coming out tomorrow is another algorithm video.

[@olivermelichercik9788]

Really enjoying these!

[@thatsenam9183]

I would love to see more videos like this one.

[@betoduarte9207]

Hello, awesome video! What would make this video even better though is if you walk through a number set and show how an example actually flows through the algorithm. Thanks for posting!

[@stith_pragya]

Thank You So Much for this wonderful video............🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻

[@bhavikrathod7493]

I have enjoyed and learnt a lot from your videos. keep going!

[@mr.webdev3700]

That was a great explanation! Good job! 👍👍👍👍👍

[@WebDevSimplified]

Thanks! I'm glad you enjoyed it.

[@chanduallada2417]

I would like to see these kind of videos... it will be very useful for interview preparation Thanks for ur efforts 👌🏻👌🏻👌🏻

[@at4371]

Thank you. Yours is excellent , but I come up with this too. step 1. get the difference (target - a[i]) step 2. search that difference if it exists in the array list using indexOf(diff) pitfall , indexOf could find same index , so we should not consider it. (n != i) var twoSum = function(a, p) { var n=-1; for( var i = 0; i < a.length; i++) { var dif = p - a[i]; n = a.indexOf(dif); if(n != -1 && n != i) { // to return [i , n] } } };

[@joematkin2554]

Hi thanks for the video, please can you explain why you didn't set the target to 9

[@lookhsu7705]

I like this! Thanks for sharing.

[@qwertykeypad789]

Love it bro, you did a great job. I learned this way of solving problems using hashing in C++ but after seeing in javascript its amazing. You explained it very well. Looking forward to see more videos like that 👍🏻

[@WebDevSimplified]

Thanks!

[@SaifaldeenSAH]

Thank you very much!, really enjoyed your explaining way, hoping to see more like that.

[@singamsettyrupeshkumar8746]

How target - current number will work I don't get tht can you explain once !

[@CH-tw7wb]

I'm always stuck with brute force methods, I just can't come up with a clever algorithm even for the easy ones. When you first started solving coding challenges, were you able to easily figure out efficient algorithms or were you also stuck with only brute force methods? If so, how did you change that?

[@djbilly5913]

I fully feel the same...Just got to keep working

[@bones1343]

I’ve struggled with the same thing until I learned about the different problem solving patterns. They’re good tools that help you optimize your solution. In this example Kyle uses a frequency counter. I’d suggest starting with easy problems using a pattern and gradually start solving more difficult ones until you really understand how it works. Hope this helps!

[@IswearIwasBatman]

Dont you have to push values from nums array into the prevValue array? How else would the prevValue array store previous values of Nums array?

[@rojehhabib648]

It is actually an object and when you do prevValue[value] = x you are basically assigning a key and a value to it

[@zafarsultanov1124]

I love algorithms pls restart this course again

[@sjsjdjyktjt2457]

Good stuff man! Just wondering, why did you set the variable "previousValues" as an object? Wouldn't initializing it as an array work the same way? Or is there a fundamental difference? Thanks!

[@WebDevSimplified]

If you use an array instead of an object then whatever the neededValue is that you are storing as the key of the object for example 1000 would be the index of the array. This would mean you would need to have an array that takes up at least 1000 spots in memory. Usually when you are working with large numbers like this or when you will potentially have many empty locations in the array then an object is better suited.

[@Jason-mx8dl]

Wait, where did the ‘index’ variable come from on line 13 when you return [index2, index]?

[@pareenjapuneet]

He fixed it at 5:54 to i.

[@pinpon163]

For better space complexity, could we also check if the current value is not already >= to the target before hashing it?

[@samuelhimmelstrup799]

What I don't get is why it is more efficient to look up if a value exists in the previousValues (object?). I mean, how does looking up something (a key:value pair) differ from iteration through something (looking through rest of the array)? You mentioned that the previousValues variable is a hash, but I haven't found a good explanation as to why it is quicker to look up something in a hash tables. Anyone knows this?

[@VedantKulkarni619]

Really awesome explanation and solution. Do you have a playlist?

[@tdpencil2811]

You can try going through every value and putting the target - the value in a hashmap, then you can constantly lookup the value to see if it's there. That is O(n) time. (not to mention freakishly fast).

[@gabrieldiaz6509]

The videos i always need

[@thattoofunny]

Great video. More algorithms please......

[@WebDevSimplified]

Thanks! I can't wait to make the next video.

[@bikramchettri9405]

Thanks for the detailed and simple explanation.

[@WebDevSimplified]

You're welcome!

[@bikramchettri9405]

@@WebDevSimplified Hey can you do a video on oop in javascript.

[@WebDevSimplified]

@@bikramchettri9405 I will add it to my list.

[@bikramchettri9405]

@@WebDevSimplified I love your explanation man, that's the only reason i am giving you a lot of trouble. Accept my apology.

[@WebDevSimplified]

@@bikramchettri9405 this is no trouble at all. I enjoy getting feedback and suggestions from viewers. I just have so many video ideas I need to use a list to keep track of them all or I forget the ideas too easily.

[@markemerson98]

awesome: more leetcodes please buddy

[@brianwebdev1958]

Thanks, that was very helpful

[@DigitalFire5000]

what is the point of the empty object. How does this empty object not always return null since nothing is pushed inside of it?

[@cesargabrielmuozcedeo3046]

It has helped a lot. Thanks!

[@anagh4802]

This was really helpful! Thanks a lot. Also more of these please.

[@baiai6509]

thank you, clear and understandable but can we solve it with a hashmap?

[@conceptualdeveloper]

Yes, Algorithm series should be good..

[@jakeschwartz4641]

Thank you for the awesome videos!

[@AnkitKumar-di2sj]

Hey! I have a doubt, in JavaScript variables declared with "const" keyword cannot be reassigned. Then how is it possible that at line no 9 the CurrentNumber is assigned values Multiple times when the loop runs. Please help

[@EntEduRealm]

kzbin.info/www/bejne/iZ27eqB7ap1pg7s watch this for all solution if you dont understand this

[@Spades340]

This was a good vid. I haven't been doing so well in coding challenges for job interviews. Do you recommend anything else for me to get better in addition to grinding Leetcode problems?

[@WebDevSimplified]

Make sure to really read the solution and fully understand the parts that you get stuck on. This will help your problem solving skills immensely and will make it so that even if you cannot solve the problem you can hopefully explain a good enough approach to solving the problem that it won't matter. Also if you struggle with algorithms like I do then focus on making projects that are really good and the employer will care less about your algorithm skills if they can see you have already created real projects.

[@stardriver8660]

Hi Kyle could you go over questions on leetcode just like this one, it just helped me so much. So many answers on leetcode is not that reliable and hard to understand. Please consider, thank you!

[@dilshodturabov]

i love you every video lesson

[@VillageJoker]

Thanks for this dude !!!

[@samueltorres2485]

Please do more leetcode stuff with detailed explanations!

[@EntEduRealm]

kzbin.info/www/bejne/iZ27eqB7ap1pg7s watch this for all solution

[@ShanilPanara]

This was great! Thanks!!

[@tr-dev92]

Hey love the entry !😂

[@fganiev]

This is great, thanks!

[@extremespartan117]

Muy bueno! I suppose you could add visuals to give a even more clearer explanation but otherwise this was really good!

[@WebDevSimplified]

Gracias. What kind of visuals would you like to see for a video like this?

[@AnnieTaylorChen]

I like it you're trying different ways of presentation. Algorithm is definitely one of my weakest points, so I would love to see of those too! :) As a beginner I don't seem to come up with the faster solution naturally, even you explained and I read your code, it took me a while to understand it. Can you add more animation to explain more visually? Such as we can visually see the index numbers flying into the object previousValues as the code runs? So what's the best way to think "smarter"? Should I watch more similar videos?

[@WebDevSimplified]

I thought about adding some basic animation to this video, but ultimately was limited on time. I think I might try doing something like that for the next video though as long as it is applicable. As for getting better at algorithms the two best things you can do are practice a lot and read/watch explanations of the solution. I would try to solve a problem and then when you feel confident about your solution check an explanation of the solution.

[@infyro]

Great explanation! Although i'm still a bit confused about something in the algorithm if someone doesn't mind explaining it to me: I'm still a bit unclear as to how 'i' is getting returned on line 13 if index2 != null is true. Can someone explain how the corresponding index is automatically returned after the conditional?

[@nestroyertv]

So as you now , you can access object properties via its key. Whats happening here is he is creating an entry in the "dictionary"(normally referred as hashmap) where its KEY=NUMBER and its VALUE=INDEX. When he substracts the current number value to the target value the result is the KEY that he needs to look for in the "dictionary", if the dictionary contains an entry for that KEY we retrieve the value , which in this case is the index, meaning we already have our combination of indexes. If not he stores the index and value as an entry to the dictionary, that way he can look it up later. Hope this helps!

[@LawZist]

Great stuff! Already waiting for you next video

[@WebDevSimplified]

I'm already planning out the next algorithm video I want to cover. It is really fun to solve the problems.

[@AmarKumar-lv1wu]

Awesome but what is index in return which you specified with the return [index2,index]

[@WebDevSimplified]

In is just a number which is the position of the array that we are at.

[@rovsenhuseynov8368]

Thank you for the useful video.

[@gomez4665]

in line 10 what is the value of neededValue? is it 9, 8, 7, 6 ?

[@MontyKsycki]

THANK YOU VERY MUCH!!!! VERY MUCH APPRECIATED!!!! THANKS FOR SHARING!!! HAVE A GREAT DAY!!! :)

[@vishnumithran4574]

hey I loved the video.. please upload similar contents

[@pswr2009]

Super helpful!

[@JustThink2000]

I like how you explain

[@savannahlin8063]

Yes!Yes! I enjoy it. It's so helpful and useful.

[@WebDevSimplified]

Thank you! I am really glad I could help.

[@vishaltaywade8069]

Really appreciate your test cases video 👍🙏 Cheers now I can able to understand js algorithms!!! Thank you so much! please do some more videos on and complications test

[@WebDevSimplified]

Thank you. I have another algorithm video coming out in a couple weeks!

[@ajwaters5323]

These are great! Definitely more of these!

[@WebDevSimplified]

I'm working on the next one right now. I'm hoping to have it out in the next week.

[@thatsenam9183]

Best video ever

[@stephanieonyekaba8274]

Just a heads up this solution ONLY works if the array of numbers are in ascending order. an array of nums such as [3, 2, 4] will not work because 6 - 3 is 3

[@flythetbm9909]

These are great. More please!

[@algorithmtrader]

the way you just popped up in the beginning always has me dead

[@vladimirjean]

That was very helpful, can you make more videos like that, I'd really appreciate it. Thanks!

[@WebDevSimplified]

I'm really glad I could help. I definitely plan to continue this series. I have already started on the next video.

[@Fieldsplanet]

Thank you so much for the vid.