Trapping Rainwater Problem | Leetcode #42

This video explains a very important programming interview problem which is the trapping rainwater problem.In this problem, given an array representing elevation map, we are required to find the amount of water the elevation map can trap.I have explained all the approaches for solving this problem starting from the bruteforce approach to the most optimal approach.I have shown how we can process and highly optimize the time complexity.
CODE LINK is present below as usual. If you find any difficulty or have any query then do COMMENT below. PLEASE help our channel by SUBSCRIBING and LIKE our video if you found it helpful...CYA :)
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[@TW-uk1xi]

This is one of the best explanations I've seen so far on the internet.

[@techdose4u]

Thanks :)

[@EngWorld-nr2ww]

Your patience while explaining is quite appreciable

[@techdose4u]

Thanks :)

[@mwshubham]

This might be the longest video on your channel. Very well covered. Thank you :)

[@techdose4u]

Welcome

[@abhilashpatel3036]

i did not even notice. Time flies.

[@MdOwaisUmar]

@@abhilashpatel3036 Absolutely, Time flies, but leaves its shadow behind.

[@rtan8780]

Dang man, you made a Leetcode Hard problem seem like an Easy. Subscribed :)

[@techdose4u]

👍🏼

[@muwongenicholus2444]

Hehehe, I was thinking the same thing. Some people are natural teachers.

[@gsmdfaheem]

Hands down the best explanation on youtube... Better than top creators.

[@user-oy4kf5wr8l]

After finding ur videos, i never watch any other channel.... i super like how u explain stuff, and different improved ways to solve it. thank you man!

[@techdose4u]

Welcome :)

[@stephc4925]

One of the best explanations! Thanks a lot!

[@techdose4u]

Welcome :)

[@codingessential91]

great video sir, i had come to understand the O(1) space solution, and your explanation is shorter and much much crisper than anyone else's. keep up the great work.

[@suryajena1575]

Happy Teacher's day. Really appreciate you as a teacher.

[@paramitagorai9087]

Generally dont prefer commenting unless really impressed. This was a great solution and I could code very easily myself. thanks for all the effort spent.

[@techdose4u]

Welcome :)

[@gautam4696]

The solution of this problem is very simple but the way sir tells how to approach a problem is amazing .

[@techdose4u]

:)

[@amitavamozumder73]

It's rare to have a video with zero downvotes! great explanation.

[@techdose4u]

Thanks

[@shantanusharma184]

Your explanation resolved all my doubts and i was able to write code by myself after watching your video for 10 minutes. Thank you

[@techdose4u]

Thanks 😊

[@mridulsemwal1396]

No one explains like this. Loved your videos

[@techdose4u]

Thanks 😊

[@DK-ox7ze]

Awesome explanation, covering all cases with detail and clarity!

[@techdose4u]

Thanks 😊

[@sugandhaduhan8707]

Best video on internet for Trapping Rain water.. I wouldn't have understood this problem if I hadn't found this video... Kudos for the great explanation....

[@YashHalgaonkar]

Your channel is really great! You should definitely have more subscriber than most of other creators who create useless roadmaps.

[@biswajitsingh8790]

Hands down the best explanation of this problem on the internet. 🙏🙏

[@PRUTHVIRAJRGEEB]

This is hands down the best explanation I have seen for this question. I am surprised it doesn't have many views!

[@techdose4u]

Thanks

[@MohitKumar-rq8hv]

TC =O(n) SC =O(1) => 24:25 superb explaination

[@techdose4u]

Thanks 😊

[@01kumarr]

giving all three possible solutions u make life easy. Thanks a lot

[@ajaygonepuri2285]

You Deserve more than a million subscribers for such a great content!

[@techdose4u]

Thanks :)

[@ayushsrivastava830]

Awesome Explanation, better from other KZbinrs

[@techdose4u]

Thanks 😊

[@muwongenicholus2444]

You sir, did an awesome job breaking this down and making it simpler to understand. Thank you for your efforts. Appreciate it

[@flyingcanopy5611]

I watched many videos to understand the concept of two pointer approach.. But after watching this video, It became so clear to me.... Next time if I am unable to solve any question I will come to this channel first... This is a very underrated channel..

[@techdose4u]

Thanks :)

[@sukeshreddy2286]

You are the best. I am now sharing with my friends!!

[@pkboolean]

thank you for this, this is extremely well explained

[@techdose4u]

Thanks

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Techdose to me is a game changer

[@ravikumar-kh9gi]

Awesome explanation . Even kids can understand after watching this video. Thank you very much

[@techdose4u]

Welcome 😁

[@venup2813]

Most underrated channel

[@chhavimishra3469]

When the content is so good, subscribing and liking are on autopilot.

[@jiosim1377]

Thanks alot! I was struggling to understand the logiv but now its clear

[@techdose4u]

Great

[@huansir1922]

thank you for your explain , from simple solution to better solution !

[@techdose4u]

Welcome 😊

[@PRASHANTKUMAR-xs9pk]

In every Questions , too much concept as well as hidden cases . When i want to try same questions after 4 days or a week i got stuck but your explanation make question easier for me. ::))

[@techdose4u]

Great :)

[@kushagrashekhawat8227]

I've watched many of your videos. Your explanations are always very easy to understand. Thank you for creating these videos; you are doing so much good.

[@techdose4u]

thanks :)

[@sanketgupta9831]

Best explanation ever with best level of calmness and patience 😊😊

[@neerajpandey7273]

I had seen your video of solving the area of histogram ..so first thing came in my mind to take 2 stacks to get left and right max ...while writing the code I realized that I can solve this without stack .... after that I saw your complete video and got o(1) space method ... this is crazy

[@techdose4u]

😂 hahaha. Very nice to see you apply the concepts of my previous video :) But there is always someone better than you 😉

[@neerajpandey7273]

@@techdose4u =D =D

[@calisthenics-]

Champ tech dose🙏 👏 Well done

[@Harsh-og5xr]

loved that o(1) space method

[@varshaprajapati6566]

thankyou so much for this video! you just made this hard task quite easy.

[@chandrachurmukherjeejucse5816]

So far the best explaination. Thank you so much sir.

[@nishantpratyush4191]

I bet this vdo has got the best explanation for the two pointer approach...thanks a ton TechDose😊

[@techdose4u]

Welcome 😄

[@santhoshmedide5279]

The last solution where time-O(N) and space-O(1) method is amazing. Came here after many leetcode solutions!

[@nikitakushwaha9572]

You are very easy and nice to understand.

[@techdose4u]

Thanks ☺️

[@beginnerprogrammingtutoria5053]

An incredibly detailed and amazing presentation. Thank you!

[@coderart__2802]

Thanks for this beautiful video, your explanation made me code myself... At the end of 16 min of the video, I understood and coded in python.

[@manojbhatt8424]

brooooooooooooooooo best explaination ever

[@techdose4u]

Thanks :)

[@PujaKumari-rp5sg]

sir you explained very nicely step by step 👌👌👌

[@aniketroy03]

Great video sir!! What an explanation! Keep uploading such videos 🙏🙏

[@techdose4u]

Welcome :)

[@sumit180288]

Very good explanation

[@ravisankarmaruramesh8112]

Index starts from 1 to arr.len-1 Totalwater+=Math.min(leftmax of current index element, rightmax of current index element)-current index element

[@techdose4u]

Nice 1 liner :)

[@rajivsarkar277]

Ur patience is appreciable

[@techdose4u]

Thanks :)

[@NaveenRawat51]

awesome explanation, the way you explained corner cases are great. keep it up

[@techdose4u]

Welcome :)

[@rachanasingh7047]

Best solution explaination to this problem. 🙌

[@techdose4u]

Thanks :)

[@akashjain4281]

The best explanation for the problems, Ty sir for ur patience and amazing explanations

[@bloody9162]

It's sad KZbin has hidden dislikes on a video, stops good videos like this from showing up first. Thanks. 38k views and 1.2k likes? c'mon guys hit the like button.

[@techdose4u]

Thanks 😊

[@gamingKlips99]

what a coincidence that we both were working on the same problem.

[@techdose4u]

:O

[@harshavarthinivr9688]

Very nice explanation 👌thank youu

[@techdose4u]

Welcome 😀

[@krishnananddubey2870]

Just explained it calmly loved that.🤗

[@techdose4u]

Thanks

[@sumeetchawla3545]

Thanks a ton for explaining solution in detail. It's really a tough job. Keep it up!!!

[@spaceship-rl5fp]

Excellent Explanation

[@khushbukareliya8999]

Best Explanation.

[@techdose4u]

Thanks

[@basiljacob3894]

Very well explained sir , your explanation for this question is crystal clear. I really liked this problem it was very intuitive

[@techdose4u]

Thanks :)

[@sujitha2339]

Clear explanation!! Thanks bro

[@harikakiran18]

Nicely explained step by step, appreciated it, understood the approach in one go...you deserve more subs & views...hope you will reach there ..:)

[@techdose4u]

Thanks ❤️

[@harishkandikatla9791]

Excellent explanation! Your channel will definitely grow a lot

[@techdose4u]

Thanks 😊

[@sandeepkharola6463]

Great work Keep going 👍

[@simrankak7045]

amazing crystal clear explaination

[@techdose4u]

Thanks

[@CSe_IT_Guy]

Best explanation 👏

[@techdose4u]

Thanks ☺️

[@monikavaid5083]

Very good solution!,

[@techdose4u]

Thanks 😊

[@prakharagarwal6237]

Nice Explanation! Thanks!

[@hnsc1]

Thank you for this video! I appreciate you drawing out the base cases and explaining everything in detail. This is definitely the most helpful video for this problem :)

[@gurubalaji5611]

Great explanation sir..hope expecting more videos from tech dose..

[@techdose4u]

Sure. I will keep uploading :)

[@athisii_ekhe6167]

you made it easy. Thank you.

[@yashkhandelwal6588]

Thank you so much you explained these questions by previously known methods because others are making it very complicated for reducing code size()

[@techdose4u]

Welcome :)

[@egor.okhterov]

As we go from left to right `max_left` could only increase (or stay the same). As we go from right to left `max_right` could only increase (or stay the same). That is why when we move pointers L and R, `max_left` and `max_right` compete with each other. First one gets larger, then the other gets larger, then the other gets larger. And we swing from one side to the other side moving pointer L and R closer to each other.

[@arjunadityarastogi2118]

Thank you , Just THANK YOU

[@huseyinbarin1653]

very clear explanation!

[@basictechs6634]

Great explanation, thank you.

[@playing_rhythms2660]

I think in the last condition it will be (l

[@ethanzhao5729]

Your explanation fits the process of how to solve a problem -- from observation of cases to generalization to optimization to final code. Pure memorization of the solution without following this process is not helpful to interviews

[@viveknandan4950]

Nice explanation.

[@cs-ope]

Great explanation!

[@paragroy5359]

Nice explanation sir......you are doing a great job

[@techdose4u]

Thanks :)

[@mpavankumar6695]

Great explanation

[@elitesharma817]

Right at 21:35 I stopped and boom my code got accepted, thanks a lot bhai, I was trying to solve with 2 pointer approach as well but couldn't deal with the water-level stuff, which you made so easy to understand and grasp, and not just that also for improvising code in such an awesome way with 2N Auxiliary space. Again thanks a lot bhai

[@depression_plusplus6120]

Nobody cares thou...keep coding

[@akshitjain2906]

amazing explanation bro!

[@GauravKumar-ue7nz]

Best explanation

[@CodeSuccessChronicle]

Thank you so much for doing this on my request.... best bro...

[@techdose4u]

Welcome :)

[@vaishaligoyal7478]

Simply Amazing!!

[@techdose4u]

Thanks ☺️

[@elenamikhaylova4287]

nicely covered thank you

[@krupaharan9406]

This saved my day :-) Thank you very much

[@techdose4u]

:)

[@abhinavmudgal7355]

Best solution

[@techdose4u]

Thanks 😃

[@milenitrivedi7561]

great explanation !!

[@sanjeevacham2400]

Excellent

[@techdose4u]

Thanks

[@nareshh74]

Thanks for the video. Can u logically explain how u chose 2 pointers approach?

[@TEJASSADADE]

you r best

[@techdose4u]

Thanks :)

[@venup2813]

You are legend 🔥🔥🔥

[@RayTayek]

very nice. thank you

[@wjrasmussen666]

This problem is kind of cool.