Hashing - Double Hashing

[@pencilcat8034]

This channel is a godsend for all who are taking the course Data Structures and Algorithms (and similar) and suffer, like so many others, from lecturers who can't teach. Myself included. I would fail and drop out if videos like these didn't exist.

[@POwens]

This saved me from failing out of my intro to data structures course (during COVID). Life saver.

[@BhargavPuri-ki7hm]

Why madam takes 7 there

[@Ahmet-dr1rq]

@@BhargavPuri-ki7hm I think question gives us

[@TheVk30]

literally the most underrated hashing legend thank you for saving me

[@abhinavsingh595]

Short and crisp explanation with example. Saved my lots of time. Thanks a lot

[@ohhCrazzy]

Thank the gods this video exist!

[@رند-س5ح]

Thank you so much this saved me from today's discussion of data structures

[@shanks9758]

Your voice is amazing ,it made fall to sleep . thank u ,u saved my life ,keep the good work

[@abdullahabod6100]

18mod7 =4 k= 4 , hash2 7-4=3 and so on for other numbers

[@christianoliver5244]

Pro trick : watch movies at Flixzone. Been using them for watching a lot of movies during the lockdown.

[@roycericky8991]

@Christian Oliver definitely, I've been using flixzone} for years myself =)

[@Mammajiprincess]

How to calculate mod..18%7 is 1.26 naa ❓

[@Mammajiprincess]

Reply plz

[@saharshamagar5059]

@@Mammajiprincess 18/7 --> remainder = 4 so 18%7=4.

[@subarux4054]

I love the way you break down the concepts!! Thank you so much for sharing !

[@faheemahmadofficial7701]

18's key hash 2 is 4 not 3???

[@anshgoel6661]

second hash function is k(mod)7 so putting the values in (7-k(mod)7) it comes out to be 3

[@olympiasol8597]

Τhank you sooooooo much ... I was looking for this for 6 hours and it was a five min solution... hate my life -_- BUT YOU ARE GREAT:)

[@KalathilAjayMenon]

A simple example was taken. Hope you expand to a bigger example with multiple collisions.

[@aswinbaiju5628]

And what happens if we get a larger value than our index limit?

[@qb415]

Normally you would do (hash1 + i + hash2) modulo array.length. This way the value can't exceed the index limit.

[@FreddyJettyJohnson]

Thank you so much, you're doing a great job ❤️

[@DuyNguyen-wx5oj]

great explanation and neat handwriting!

[@heyyoga7515]

You are an excellent teacher! Did great on my quiz because of this video ❤️

[@cannedshoes]

You are a fantastic explainer. Much love from Texas :) and pray I pass this exam!

[@rahulthapa7880]

Very nice Clearly understand Your voice is awesome ❤️❤️

[@nqnqnq]

there's an issue with this, you can get out of bounds. let's try to hash key 12, supposing index 12 is already occupied. hash1(12) = 12, hash2(12) = 2 you'd need to add key 12 at position 14, which doesn't exist. fix: position should be given by (hash1(key) + j * hash2(key)) mod size.

[@kevinkingsly]

This is the correct method

[@МартаДяків-т2л]

Thank you so much for your videos! You are just the best!

[@sovonmaji2929]

Maam , when addition --- h1(k)+ j*h2(k) ,,,, greater than 13 , then what to do?

[@DidierWyche]

Thanks for the forecast! I need some advice: My OKX wallet holds some USDT, and I have the seed phrase. (alarm fetch churn bridge exercise tape speak race clerk couch crater letter). How can I transfer them to Binance?

[@valeriosilvestro7067]

why 7?? is it an upper bound of 13/2?

[@VivianGameCollections]

WHAT A LIFESAVER, THANKS AND LOVE YOU SO MUCH, HOPE YOU HAVE A NICE DAY

[@eeni14]

Thank you so much! The explanation is really clear

[@navyashalini2951]

y u have taking in hash2 (K)=7- kmod7??

[@miguelnuno928]

Beautifully explained

[@tahofu2618]

what do you mean ... 5 + 0 in to 3, then 2 + 0 in to 1? I thought it was supposed to be hash1 + hash2 ??

[@mahimanshah7851]

Yessss

[@mahimanshah7851]

Even I dint get that part

[@hakimmustafa3349]

in to = multiply = "j" state in the formula

[@gautamgandotra9965]

this is life saver. thank you

[@hasan_shans]

Very nice courses! Thank you madam!

[@mma4605]

Great job explaining!

[@Guru-UPSC]

Why u chose hash2 a particular function. Plz, elaborate the reason for choosing that function. Thanks

[@randomname8750]

she used an arbitrary function

[@yousafraza7747]

Saved my day

[@Albatross-vn7lq]

that was too simple..Thank u mam

[@terryrodgers9560]

amazing explanation, thank you

[@gandreyhohlov1030]

Thanks! But how do SEARCH (not insertion) works? For example, how to find 44, if 18(at index 5) was removed an is EMPTY?

[@briannguyen1134]

for this example if 44 hash 1 was 5 and hash 2 was 6. Would we go in position 6? or would we do location of 5+(6*2)mod 13?

[@divyaaskihal2194]

why did u take 7 while calculating v alue of h2?

[@ashishthanga13]

r-k mod r is the formula and r should be a prime number less than the size of hash table

[@abhinavsingh595]

Its given in question and changes according to question.

[@木林海风]

Beautiful handwriting and cute voice ♥

[@makeitmakesense-e3x]

It would have been nice if you showed how you got the hash 2 values

[@edoardogribaldo2870]

Great explanation, thank you very much!

[@VersatileAnthem]

mam why don't you upload new videos .your videos are far more better then university professors !

[@oduyhung215]

thank you very much for your videos. I have a question , what will we do if the collision occur at the final key when using linear probing and quadratic probing ?

[@pvedits7977]

Nice explaination

[@sherrywu161]

Really helpful!! very clear

[@Anonymousgirl620]

Thank you sister helped a lot

[@madhusudandas8411]

maam, are you doing MS in AI ?

[@oliganguly2051]

thank u friend.. just for this video i can clear my concept

[@1muharremyilmaz]

Thanks, From TURKEY

[@theapex6097]

what would happen if sum of two hashes is more than the table size?

[@robertsterenchak8431]

Short and concise :) please make more videos like this 👍

[@justtil6749]

Amazing explanation, thank you so much

[@wallotube6359]

Very nice.continue like this

[@gayallaksara5256]

Why didn't you modularized the double hashing function by the table size

[@niazahmad7823]

Yeah she made that mistake she has to take modulus of the whole h1 plus h2

[@jahehs]

Where did you get the 7?

[@hieutrongoan4656]

love your hand writing :D

[@gauravojha1748]

Ye hash 1 nd hash 2 kha se aaya

[@jakobjensen8228]

Anyone here know what m in this statement could be? H2(k) = 1 + (k mod (m - 1) I get that it's the hash2 taking the key as input, but what would m represent here? A value incrementing if the spot it taken perhaps?

[@J2KJonas]

The m represents the size of the array so if you have got an array of [1, 2, 3, 4, 5, 6] then the m is 6. AAU gang here to save you (skal selv op i ALG)

[@jakobjensen8228]

@@J2KJonas King, gir en øl i gaden.

[@nandinigorla]

How can u take that mod 13. If they given we taken.... right...and for hash 2 also how can u randomly take 7 and for the mod also take 7

[@fisayoojo9331]

I don't know how you manufactured the 7 in the first four lines and you didn't explain that. Had to use other resources to figure that out.

[@AdvayBasavaraju]

Wowee great vid, helped a lot thx so muhc tee hee

[@Iam_Smk]

Short and sweet

[@dipanshunautiyal4234]

Vo 11-kmode11 ku nhi hua?

[@rolandor9678]

wow, me encanta que excelente explicación, muchas gracias.

[@tafveezahmad9692]

ERROR IS THERE (hash1(k) +j*hash2(k))modN will be there you have missed modN

[@bedtimestoriesforkids9755]

Are you from CMU?

[@vamsikrishnach9278]

Excellent job madam 🤩🤩🤩🤩🤩

[@BhargavPuri-ki7hm]

Why madam takes 7 there

[@rakshithgrajcse330]

very much helpful thank you

[@zenekquerky7255]

It can happen that hash1(k) + j * hash2(k) > 13 I think its possible, despite that 7 and 13 are prime. In your example you had "Lucky numbers" :D Otherwise you end up with index out of bounds.

[@chainsawman-stoic]

doesn't matter if index is out of bounds

[@RustyBagel127]

@@chainsawman-stoic so if it becomes out of bounds then what happens?

[@nqnqnq]

@@chainsawman-stoic it does

[@Dwika34]

I think the first thing you should say is that double hashing only works for a prime length array. The second thing you should fix is: I think the formula should not d be hash(k) + jhash2(k), the reason being that I tried it using a while loop in java and it enters an infinite loop . By your approach if the j is zero then the code would keep on repeating itself(do keep in mind that the second function cannot have the value of 0 in double hashing). So it should always start with hash(k) + hash2(k). So it should look like this hash(k)=hash(k)+hash2(k). This way we would always reach the intended way purpose of double hashing which is to increment hash(k) with the value of hash2(k). Like many beginners, I think those 2 points would make it easier for us to grasp and comprehend the material. Thank you, otherwise great content and delivery

[@richardpaul5427]

I think that starting with j = 0 is fine, there doesn't seem to be any reason why you'd need to start with j = 1. Also, double hashing can work on non-prime length tables, if the hash2(k) always outputs a number that is not a factor of the size of the table.

[@mohammedafzal5720]

How did you calculate H1 and H2?

[@AshutoshSingh-qj1gm]

taking mod values, like we do for other hashing functions

[@fisayoojo9331]

@@AshutoshSingh-qj1gm not exactly there's sth about prime numbers for H2.

[@elkleelekee]

@@fisayoojo9331 it has to be of q - (k mod q) where q is smaller or equal the size of the array

[@berndlauber6328]

perfect teacher :o))

[@bellenature143]

How to get hash1 and hash2 values

[@jayprakashjaiswaldeptofcom1250]

really ,u dont think its important to tell hwo to take second hash function ?

[@ilhemwalker9145]

Thank you sooo much ❤

[@ΠαναγιώτηςΧατζηδαυιτίδης]

thank you kind woman

[@zum4342]

THank you very much

[@bouboudubinks6959]

amazing

[@mohammadgh5768]

Thanks tomorrow I'll have a ds exam

[@nguyenquanghuy963]

thanks you so much

[@ort.school]

cool, thanks

[@mdkanokhossain1445]

Thank You

[@kumarnigam8078]

dought free lecture :)

[@nhat1286]

nice!!!!

[@kantipudiavinash5743]

Nice voice❤

[@faheemahmadofficial7701]

11 mod 7 is 4

[@fkhan2416]

The hash 2 value of key 44 is 1 not 5.

[@SirSimon-zg2rm]

Thanks!!!!

[@karthikeyan4375]

I want extendable hashing

[@przemysawcwiek8306]

HELLO im from poland, im young programmer, im have algoritmos kolokwium, thx for help.

[@anandhakannan2435]

I lub u😻

[@er_surya__7__118]

😇😇😇😇

[@nomindulal3102]

h2(K) i didn't understand

[@nirmishrathod9813]

Explain me the calculation of " hash2 "

[@sinto4105]

you have taken easy example

[@sinto4105]

take some complex example

saolasın hintli bacı

[@gangstergangster5454]

eyy ooru madam meddhi mee number pettandi please

[@sameerthakur851]

mam wiTh face cam pdao

[@aakashsuresh2566]

Math in Ohio 5+1*5=10 lmfoa 3:40

[@JacksonFilmsMovies]

It is 10 bro

[@Fullpoor69]

Aint no way