Design HashMap | Live Coding with Explanation | Leetcode - 706

[@AlgorithmsMadeEasy]

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[@SurajSingh-tz1wr]

This video is so self-explanatory and the solution is so clean. Loved this video. Thanks a lot!

[@AlgorithmsMadeEasy]

Thanks !!

[@satheshbm92]

The clearest explanation, I found for the problem. Great work :)

[@AlgorithmsMadeEasy]

Glad it helped!

[@yusufazam1113]

If I am not mistaken this solution is technically incorrect, as the problem states you must insert a key value pair. In this case the solution only stores the value and uses the key for indexing purposes only.

[@pritisharma8980]

very clear and concise explanation,and in a short video,thanks for posting

[@AnkitKumar-ys7vs]

Thanks

[@AlgorithmsMadeEasy]

Welcome

[@fantasy9960]

best of the best! thank you for your effort !

[@codedestiny6955]

Keep learning keep coding

[@AlgorithmsMadeEasy]

yes 👍 😊

[@abcdeereijgfhd3215]

This is the clearest explanation I have found so far. Thank you. BTW your typing speed is unrealistic. Did you fast-forward the video or just have the fastest finger? haha~!

[@AlgorithmsMadeEasy]

Thank you so much! Haha.. I fast forward. 🙂

[@YNA64]

Hello thanks for the video. I have a question regarding the time complexity being O(1). Why is that so? Should it not be O(n) because for each method, in the worst case, you will have to traverse through a whole list? Hope you could clarify, thank you.

[@shreyamduttagupta7527]

Even I had the same question. For best case scenario, the put method will have O(1) time complexity if the key is not available, but if it exists, it will have to iterate through the whole bucket to find the key and update. I feel the time complexity should be O(N/K) where N is the number of keys and K is the Size taken which is 769. Let me know what you think!

[@trevorjomeihoshiwara2961]

I agree about your assessment in the worst case scenario. I believe it should have been stated as O(1) time complexity amortized. On average with a properly implemented HashMap, entries, deletions, and searches should execute in constant time. This all relies on the fact that there is a reasonable load factor (The size of the hashing array vs. the number of elements to be inserted).

[@xinniu3145]

Thanks for sharing this answer, could anybody explain why the time complexity is O(1)? and why space complexity is O(N)? And also, at 4:18, why size of 769 makes the hashing efficient? Thank you!

[@iliasolovev266]

Why did we use toRemove variable? Why just we din't remove in right there like map[bucket].remove(entry)? Because it can cause ConcurrentModificationException?

[@ujjvalsharma5055]

Wonderful video!! Keep making great videos

[@prachiraval4728]

How to print the final map after giving put and get method

[@ammarshareef462]

How are we solving the issue of collisions in this problem.

[@sase1017]

pretty awesome, thanks!

[@AlgorithmsMadeEasy]

Most welcome!! Don't forget to subscribe!!! :)

[@ashwanisingh4787]

Why are we creating Entry class.Can u plz explain

[@sanyamgoel1259]

Can we do using simple array?

[@AlgorithmsMadeEasy]

Yes, we can do it. But that would not represent the actual implementation. We have shown that too in the video.

[@sammedsankonatti9642]

why do we use Entry object to iterate like for(Entry entry : map[bucket]). didn't get that.

[@tusharjain7433]

map[bucket] is the linked list have a type of entry objects

[@dhruvkaran9724]

in remove when we found our key y we did not break; ???

[@rechinraj111]

Why have we choosen SIZE as 769 ?

[@AlgorithmsMadeEasy]

you can choose any arbitrary value!! usually, we try to select a large prime number!

[@rechinraj111]

@@AlgorithmsMadeEasy why only PRIME nos?

[@AlgorithmsMadeEasy]

not only prime numbers. you can select any number. prime numbers give us less collision so that's a recommended practice.

[@rashmikiranpandit8962]

For both the methods, the space used was almost the same, I wonder why did we use so complex method then

[@AlgorithmsMadeEasy]

The complex method is more in line with what an actual hashmap works on. It is discussed by keeping the interviewer in mind.

[@ramkumar_balu]

Why array of LinkedList? Can it be another DS?

[@AlgorithmsMadeEasy]

If you see the internal working of HashMap. You will find, it used array of LinkedList.

[@harishreddy7751]

This solution is good but I'm 100% sure the follow up question would be on collision which was not handled here and needs to be handled

[@shreyamduttagupta7527]

What do you mean? I think she explain collision and the reason of 769. She is using Modulo operator to calculate hashCode and a larger prime number to handle Collison. Isn't that enough? Let me know what you think!

[@nishantchoudhary5073]

your solution in this video are not working

[@lokeshsenthilkumar4522]

Awesoom try to post the video before 5pm pls

[@AlgorithmsMadeEasy]

Hi Lokesh, KZbin channel is not the primary job to us. We have our regular offices and can't make videos in office time. So you would see the delay. Hope you understand.

[@luminraja09]

kzbin.info/www/bejne/f4TMo2VmbLeogbM is this the special case to handle the collision ?