Leetcode Solutions | 1027 | Longest Arithmetic Sequence

[@dakshsharma8006]

best explanation of this coding problem. Hats off!!!!

[@rahuldasari1886]

Really very good explanation video....

[@pavan-nc2gs]

stoped my coading practice beacause of this problem, And now resuming because of this video, thank you so much sir.

[@raj_kundalia]

I think this is the best explanation out there!

[@RAHULYADAV-zr5fq]

Really loved the way u explained!!

[@sachin_getsgoin]

Very good explanation. Indeed the question is tricky and it was difficult to build the intuition to solution. Appreciate your honesty and the fact that you acknowledge the problem is difficult.

[@rahulmanghnani3081]

Hi Sachin, thank you for the warm feedback! :) Glad my explanation was helpful, Happy LeetCoding!

[@soumyakarmakar6470]

Awesome Explanation !!!!!

[@swapnildarmora6258]

I would like to say that this best explanation without actually jumping into the coding first. What I liked about your approach was you explained it in a way that I was able to grasp at the beginning itself and didn't need to watch the entire video.

[@bishwajeetsharma3498]

I myself struggled a lot, spent like 5 hrs pondering tried but i was doing a mistake i was creating a map of all the common differences which was both time and space consuming. Thanks for the video!! Helped me save my night for other problems!!

[@mrprime557]

Did the same. created a map of common difference.

[@anthonykostal1633]

Great Work!

[@MehtabButt-q2f]

please do leave useful links in descriptions

[@mounishsavier5774]

Great solution, thanks!!

[@tushartilwani9540]

Awesome explanation Rahul. Keep making more videos.

[@shobhitkumar6820]

Really loved your honesty sir...that sometimes its not easy to come up with a solution....

[@rahulmanghnani3081]

That's true :) Thanks Shobhit!

[@sainathreddy2632]

by just watcing first 12 min i had coded it up and it worked on first go : )). thank's a ton

[@pulavarthichaitanya3403]

very good explaination

[@naincyrastogi6304]

Thank you so much.. You have explained it very well... Seriously... It's awesome. If someone will try to listen you with the calm mind he will get to know the logic of solving this question. Really thank you so much.

[@adityakrishnan3133]

Thank you. Your video helped me understand the logic to solve this problem. Much appreciated!

[@burakarslan1885]

That helped me a lot. Thank you very much mate. Keep going

[@shreyasjain9382]

Thanks man! The explanation before coding and the verbose code does make things crystal clear. Keep up the good work :)

[@AyushiSharmaDSA]

Great explanation, helped a lot. thanks :)

[@gauravniranjan2770]

Thank You! I was struggling for quite some time in this question.

[@sushmitakumari8252]

thanks best explanation

[@ash_j3]

9:40 [[ : ], [3 : 1], [6 : 1, 3 : 2], [9 : 1, 6 : 2, 3 : 3]] I think, this should be the final array, although it doesn't make any difference to the final result. Correct me if I am wrong. Nice explanation, BTW!!

[@rahulmanghnani3081]

Hi Jatin! Thanks for your comment! Actually no, [[ : ], [3 : 1], [6 : 1, 3 : 2], [9 : 1, 6 : 1, 3 : 3]] is still correct because when we compare the difference between the current element and any previous element we update the current element's dictionary only for the difference between the current element and the previous element, we do not update all dictionary elements of the current element. Since there can be only 'one difference' between the current element and the previous element, we end up updating the value for only one key whenever we compare the current element with any previous element. Also, if you look at the array, you cannot find a scenario where you have 3 numbers separated by a difference of 6, so 6:2 would not be a valid dictionary entry. Hope that clears things up! Have a good day!

[@sanjanar9198]

Awesome explanation, I could not find any explanation to be better than this

[@e.sowmia]

thanks for your vedio

[@think__tech]

14:03 One can clearly see the amount of effort you are putting in trying yo explain the concept, really liked that. It was a wonderful explanation thanks! :D

[@rahulmanghnani3081]

Hahaha! Thanks a lot Devanshu, made my day! :)

[@ritesh_sinha]

Crux at 6:16 does the trick. I could code the solution in one go with just that line. Great video

[@gautamarora6516]

Thanks! This video helped me a lot :)

[@tanmayagarwal8513]

Great Explanation!! Really we can see .. u really put some efforts in it!

[@narutouzumaki-yx9mw]

Is there a way to solve this using memoization?

[@gandhijainamgunvantkumar6783]

Thank you for amazing explanation :)

[@yashjain1492]

if we iterate the j loop from i - 1 to 0 then why it gives wrong answer on some test case?

[@yili9725]

really nice solution and explanation. I just think line 21 is not needed.

[@tejakayyala5795]

Great Bro

[@tejeshvaish17]

thank you sir!!

[@arpit_singh10]

Great explanation :)

[@rahulmanghnani3081]

Thanks a lot, Arpit! :) Happy LeetCoding!

[@prachurjyabasistha4682]

Really nice explanation but I think that the elements have to be distinct for the solution to work

[@amarshinde5863]

finally understood 😄

[@nagalakshmi1385]

very good explanation

[@rahulmanghnani3081]

Thank you so much! :)

[@sathya1657]

Thanks sir

[@taimurkhaliq4477]

God bless you. Also you have over 30k emails to check.

[@timzhang6651]

Good job explaining. When approaching this problem, I thought the question asks to find the maximum of increasing or decreasing subsequence in an integer array 😂.

[@ShivamSingh-me1nb]

Nice explanation

[@rahulmanghnani3081]

Thanks a lot, Shivam! Happy LeetCoding! :)

[@saurabhshukla4900]

at 9:57 the difference 3 has occurred thrice before 12

[@vineethsai1575]

Python solution for the same logic. ``` class Solution: def longestArithSeqLength(self, nums: List[int]) -> int: length = len(nums) dp = [collections.defaultdict(lambda: 0) for _ in range(length)] maxValue = 1; # because min length is 2. There is atleast 1 difference subsequence for i in range(length): currentElement = nums[i] currentMap = dp[i] j = 0 while j < i: difference = currentElement - nums[j] previousMap = dp[j] newValue = previousMap[difference] + 1 currentMap[difference] = newValue dp[i] = currentMap maxValue = max(maxValue, currentMap[difference]) j += 1 return maxValue + 1 ```

[@harvitech8871]

Nice explanation but the notifications sounds were a bit annoying

[@rahulmanghnani3081]

I totally understand and I apologize! I will make sure to keep my phone off the next time :) Thank you for your feedback, Happy LeetCoding! :)

[@aayushrajput1261]

Used same approach in cpp but got TLE in leetcode.

[@manideep1218]

us a array instead of unordered_map and add 500 to the value(difference) so that u can store in the array

[@adityakajale4403]

use a array instead of unordered_map and add 500 to the value(difference) so that u can store in the array now try to solve it

[@pisanghangus2]

nicesah

[@pabloarkadiusz4687]

Lol. i Came up with this solution and discarted it because though that it can´t be that strange xd

[@rahulmanghnani3081]

Hahaha, yup that happens! :D

[@engineerhiteshahuja]

Hey rahul, Nice explanation. Don't you think that this solution is going to have huge space complexity in contrast to other dp solutions? Miles to go before I sleep. Keep practicing and keep delivering good videos. Try to reduce the length of videos if possible by doing the editing in the end.

[@rahulmanghnani3081]

Hi Hitesh, thank you so much for the honest feedback! I will work on it :) Yup, I agree with you. This solution does have relatively greater space complexity but I like this approach because it is more intuitive to me :)

[@hhcdghjjgsdrt235]

can you optimize my code ?? public class Solution { public int LongestArithSeqLength(int[] nums) { int result = 2; for (int i = 0; i < nums.Length; i++) { int current = nums[i]; for (int j = i+1; j < nums.Length; j++) { int diff = (nums[j] - nums[i]); int nextInd = j + 1; result = Math.Max(result, Helper(nextInd, diff, 2)); } } return result; int Helper(int currInd, int difference,int R) { int res = R; for (int i = currInd; i < nums.Length; i++) { int differ = nums[i] - nums[currInd - 1]; if (differ == difference) { res = Math.Max(res, Helper(i+1,differ, R+1)); } } return res; } } }

[@MrSpidm]

Why can't you code in swift ? There also exists a huge iOS community to support you.

[@Om-mb8cv]

I was finding it hard to understand from other solutions, thanks for explaining it properly !! I would love to connect with you and learn from you, if possible would love to talk to you on LinkedIn