2.6.2 Binary Search Recursive Method

[@atulgunjal6627]

Your mastery in converting complicated algorithmic steps into the simple stages is impressive.

[@mohammadfaisal3649]

i wish there was a coding part also. i Have NEVER seen a teacher with this level of understanding in data structures.

[@mansoorkhattak5072]

Sir you are hero , superb !! Allah lambi zindagi de :)

[@nitiKT]

Bari Sir, hats off to you. I brag to my friends that I was your student and thought me DSA during my engineering and every time I have an interview I make sure I go through some of your videos..

[@preethamm.n1161]

Sir, u are my hero sir 👑God of algorithms 👑 😇🌞😎💻 "Simply in the nptel outdated teachers are teaching the same concept for hours together And u are awesome sir without missing out any of the concepts u are teaching better than them sir" As enstien said "if u can't explain in simple ,u have to understand well enough" For the above qoute Ur best example sir Thank u sir it's helping me a lot God bless u sir

[@jessesinger4790]

31/83 videos in, bought your course on data structures. Maybe jumping ahead of myself, but you're amazing at explaining this.

[@mohamedatef3526]

This is, by far the best tutorial for learning binary search I've ever seen. Many people have sufficient knowledge and skills and they try passing them to others but a few of them can deliver them in a convenient method like Abdul Bari Does.

[@abhilashpatel3036]

Being from non cs background, it was very difficult for me to find time complexity of a algorithm. Your recurrence relation series has helped me alot.

[@saran5671]

There is a slight mistake in your algorithm if(l==h) will throw you a stackoverflow error instead you should use if(h

[@mustafamahmoudahmed1778]

Thanks for this helpful playlist, you are the best. I tried to implement the algorithm as it is in the video, it didn't work except for values already in the array. My recommendation: 1- remove the if block 2- Modify the else block to be "if (l h" Here is my implementation in C++: int BinSearch(int l, int h, int key,vector arr) { int mid; if (l

[@backpropagated]

Thank you for these videos Abdul Bari. I normally struggle to learn from videos, but your concisesness helps so much. I know that my focus won't be wasted, so I can listen intently for the full video.

[@eva42sh]

cannot express my gratitude. Thank you Mr Abdul - all of your videos are priceless! you're a legend. Thank you for helping to improve

[@protek8]

I never understood recursion, but after watching this video I know all of it thanks, Abdul sir!

[@Swansylinks]

You're so unique, I failed algorithm because I didn't understand it when my lecturer taught me. I am sure I will scatter my Saturday's exam curtesy of you Dr Abdul Bari.

[@StefanoCocomazzi93]

I can only shay Thank You. I Just passed my algorithm exam with honors. Thank you, thank you and again thank you

[@luckywhite7241]

Great to come across your clips on algorithm, you lecture just rolled away huge pressure off my neck. Thanks Sir

[@eva42sh]

Thank you Mr Abdul - all of your videos are priceless! you're a legend. Thank you for helping to improve

[@zureka3242]

Sir in your recursive code, you didn't give a condition for when the element can't be found, i.e. you have to give a condition that when l>h return -1. Other than that amazing lectures

[@vineetwidhani8513]

The first condition where l==h is when the algo will return 0 when an element is not found, in case the element is not found, before l becoming greater than h , it first becomes equal to l.

[@AbdullahSiddiqui949]

now i am clear you teach it better then , even our university teacher.

[@Farahat1234]

From which university you are?

[@subramaniyanvg6367]

Sir you should be guiding students for companies like google and amazon. Also please write a book on Data Structures definitely I will buy.

[@khale-d]

this also is a good algorithm: def RBinarySearch(arr, value,l = 0,h = 0): if(l>h): return -1 mid = int((l+h) /2) if(arr[mid] == value): return mid elif (value > arr[mid]): l = mid+1 else : h = mid-1 return RBinarySearch(arr,value,l,h) arr = [1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29] print(RBinarySearch(arr,25,0,len(arr)-1))

[@intuitivej9327]

I can finally write the code after this lecture series! Thank you from South Korea.

[@dmsnm]

One question: Aren't we suppose to return 0 for successful events and -1,1, etc for unsuccessful events? Great lecture series btw.

[@66renegade66]

Correct. The tutor here has array indices starting at 1. So function can return 0 if key not found. Most languages have array indices starting at 0, so return -1 if not found.

[@weixinwang52]

That's the thought I was looking for, thanks

[@CLG111]

I've had two algorithms courses one as an undergrad and also one as a master's student and I was always kind of iffy about my understanding but now I understand and my learning is complete thanks to Professor Bari.

[@chaulethanh752]

I can't see the method where you find the first occurrence of the element to look for and what if your array r

[@gayatri263]

God bless you and your loved ones..... Keep rising... 🥰😘

[@devesh1697]

I know my DAA is in safe hands now.

[@amuzak9063]

and 2 years later, I do too

[@yogeshwarsingh6151]

@@amuzak9063 lmao Samw😂

[@bageshwardham-1M]

DAA or DSA??😅

[@ApniKaksha_bonded]

​@@bageshwardham-1Msame question

[@colemannelson5392]

Made this very easy to understand, divide and conquer!

[@FELIPE-vj7vd]

I have just one thing to say: Thank you!

[@akashbose5228]

Sir instead of that if l==h block if we just check l>h and return wouldn't it still do the same considering we are already comparing with a[mid] later? Thank you

[@chaosavenger2]

you'd also have to check if your lower bound is greater than you upper bound, such as for the input [2,5], target = 0

[@saivishwanath958]

Great content . Quick correction : The recurrence relation is 2 * T(n/2) +1

[@saifurrahman3961]

I am facing a problem with this algorithm, if the key is not found then the function is not returning what's expected. The program just terminates. I think there needs a (l > h) terminate condition.

[@senaholiz]

I noticed this too. This can easily be solved by another if chain in the first if. if () { ... }else if () { ... } else { return -1 }

[@initalAS]

only one word sir """SUPERRB"""

[@anbarasanv5625]

passing arguments (l,h,key,Arr).. I think array missing in the passed arguments sir

[@anirbanmukherjee5591]

Call a constructor.

[@vineetwidhani8513]

In such cases array is always declared as global variable. You can also pass it as argument but that would take more system memory.

[@imgeek4282]

@@vineetwidhani8513 Pass the reference then?

[@anthatikalyan4995]

I love your way of delivering... Awesome

[@jayadevpulaparty1341]

One thing i observed is that if we take an even sized array, we are getting tree of depth 5 instead of log(16)= 4. Please let me know if my observation is valid

[@vijaypalmanit]

super sir, your videos are really very helpful, you make the subject simple so that even a new student can understand, I am able to write programs watching your videos, thank you so much.

[@amberchawla7930]

Sir i dont think l > h , case is covered which actually could occur

[@codingvibesofficial]

Why are we using return in if else block..instead we can avoid return in if else block I think return mid is sufficient

[@josephsebastian1244]

bro its good.my friend suggest u and i was lucky i got u

[@practicemail3227]

I'm a non-cs background student and even i can understand such simple explanation. Hats off to you sir for your contribution sir.

[@tubex1300]

Master what kinds of problems we can divide? like in case of the binary search above?

[@supremoluminary]

What if there are duplicate values? We want the first one. Input: array= [1, 5, 5, 5, 6] value = 5 Expect: 1. But your approach would divide the array in half and check the mid element, array[2]. array[2] is 5, and that matches the value you searching for, so your function would return 2. Instead, it should return 1.

[@subhamroy5619]

a=[3,6,8,12,14,17,25,29,31,36,42,47,53,55,62] z=int(input("Enter the number you want to search: ")) low=0 high=len(a)-1 while low

[@AmulyaKishoo]

Binary Search has only Divide strategy and not conquer strategy. So, does it come under Divide & Conquer ?

[@jonelleyu1895]

So helpful! Thank you Sir! Btw would you please enable the subtitles? My english is not very good. Thank you.

[@garogarabed6196]

The array starting at index 1 is confusing me, but in general awesome video! Thanks a lot!

[@anupampaul2907]

Sir, where is the condition to check (l>h)??

[@adityac4418]

how can be lower limit greater than the upper limit

[@amberchawla7930]

@@adityac4418 it can come think of a subarray of 2 size and then mid is 0 index , now consider key smaller than mid

[@sahilchaudhariarsss]

mistake in algo-----> not checked condition for low>high if(low>high) return -1;

[@deepak1291]

Algo worked fine when item is inside the array or greater then the array elements but fails, when item is less then the entire array elements. Pass: 1-> When item is present 2-> When item is greater then all the items present Failed: When Item is less then all the items int[] a = {2, 3, 4, 10, 40}; int searchItem = 1; int low = 0; int arraySize = a.length; int high = arraySize - 1; private static int search(int[] a, int low, int high, int searchItem) { if (low == high) { if (a[low] == searchItem) return low; else return -1; } else { int mid = (low + high) / 2; if (searchItem == a[mid]) return mid; if (searchItem < a[mid] ) return search(a, low, mid-1, searchItem); else return search(a, mid+1, high, searchItem); } } Condition need to be added : Instead of: if (low == high) { we need to put one more check there: if (low >= high) {

[@rohanMJ]

shouldn't we have to pass array into the recursive function? or should array be a global variable. Am i wrong guys?

[@intuitivej9327]

Yes we need to pass array to the fuction. We can just capture the main logic behind so you will have no problem if it is kept in mind.

[@prateeksharma2839]

Please sir ...i'm little bit confused... I need your help...please reply and tell me that binary search iterative method also use divide & conquer strategy or only recursive approach is using divide & conquer for binary search

[@shardhajanani2962]

If they ask binary search in question paper which method have to follow either iterative method or recursive method ???

[@shardhajanani2962]

Ok sir..thank you so much 😊

[@mohammedadel8948]

Thank you for your hard work.

[@dark4o90]

but this is not really D&C algorithm as it just reduces the problem but it does not generate separate results for sub-problems which are later merged on like in quicksort or parallel sum

[@pranki2254]

Sir, I just bought your Data Structures course on Udemy. I have working experience in Java but the course is taught in C and C++, will it help me in detail with respect to Java or will i be missing something?

[@akshaysharma8235]

Sir, a function can return the function itself which you have done int binary search algorithm ???

[@RameshMaity90]

Batch of 2023 ❤ still masterpiece for Algorithm

[@rachit007]

Great explanation

[@priyankagehlot9945]

Thankyou sir 🥰😄

[@shobhitlamba3495]

why aren't we using "while(h>=l)" in the else statement?

[@YanMinThwin]

Thank you soo much sir

[@pmahaur962]

Sir what's the meaning of return in coding why we do this and when?????

[@SRNR_PODCAST.]

a gold mine in youtube

[@rahulraj-hn1cd]

Superb Sir ji thnq for giving algo video

[@saivaraprasadmandala8558]

why isn't the order of binary search is O(log n to the base 2)

[@adityakumarmishra5556]

Sir time we get by iterarative algorithm and recursive algo is same log(n) so which one is best for use .

[@mohammedrizin3015]

sir do we want to define the l and high values in recursive algorithm

[@sahilgurung8876]

Btw why is it t(n/2) for the returning functions even if rbinsearch function takes t(n) time they are the same aren't they

[@pragmatic_p8]

it recursively called for only half of the array numbers...so n/2

[@auroraz6911]

@@pragmatic_p8 Thanks for your clear explanation! I was also confused about it, but now I totally understand.

[@thenerdycoder07]

Best Ada teacher♥️♥️♥️♥️

[@adipratapsinghaps]

Sir, how is BinarySearch Divide and Conquer? We are not dividing the problem into multiple sub-problems. We are, at every step, decreasing the problem into a single smaller problem. We don't divide the array into 2 halves at each stage and process both arrays. I read on internet it is a Decrease and Conquer problem. Is this true?

[@superawesomeninja2]

This is a truly great video, but wouldn't we want to include the sorted array as one of the parameters for the recursive binary search?

[@shishiradhikari1911]

Don't we need to pass the Array as one of the parameters (which in this case is A)? It does not really matter but if you want to be pedantic then I think you should pass A as one of the parameters too.

[@shishiradhikari1911]

Makes sense.I was just being pedantic. Thanks for these awesome videos!

[@jairam1741]

If element not found you return zero but what will happen if index of the element is zero?

[@downtowngedi]

Sir, why did you put a condition to check whether l is less than h?

[@downtowngedi]

What if the element isn't present in the array. The call should be returned rather than calculating mid in else.

[@krishnamohan1809]

Nice video sir,but i think it will not work for cases like key=1 and array=[2,3];

[@KhwiloWatai012]

The base case should be: if (low > high) { return -1; } Since 1 is less value than 2, the first element of the array, the recursion in this lesson will run without reaching its base case. At some point, high will be less than low which would then result in an error. So it's best to define your base case as the above example.

[@esgmodiyt1359]

Besttttttttttt teacher

[@gateeasycse]

Sir generly any problem written in iterative time complexity take more or equal to recursive ?

[@gateeasycse]

Abdul Bari sir iterative and recursive are equailvent power? If yes then y we are using recursive ?plz explain .greedy, dynamic approach following iterative or recursive or both

[@basavrajningadali4919]

sir please make videos on python also

[@divyanshutripathy3484]

Wouldn't the code still work if we only wrote what's in the main else block?

[@kirandeepsingh9144]

where is combine step in binary search after divide and solve step?

[@kirandeepsingh9144]

+Abdul Bari without combing it full fill the divide and conquer guidelines? as it says there are 3 phases divide conquer and combine

[@abhisheksinghrajput2624]

Thank you sir and great explanation

[@TTAGGGTTAGGG]

never though I'd have Prakash Raj teach me CS

[@Btech_baatitulu]

Not satisfied 😢

[@vigneshprabhu7626]

I love u sir you're my bahubali

[@karanssh]

4:46 you might want to mention that we return 0 after the last else block in case element not in array. Also, return 0 denotes success in some languages, better to return -1 or an error but that's just down to my personal preference

[@adriann789]

No need to return in the last else block since returning the recursive function will eventually return l or -1 (not found) as per the first if (l == h) condition. By continually halving the array, we will eventually hit the base case where the array will only contain 1 element.

[@45_vrushalinikam19]

Thank you🙏

[@seiftahawy54]

Sir, you're great !

[@raakuu]

You are great❤️❤️

[@syedfamily1]

Thank you x 100

[@ihsannuruliman3656]

did he forget to input the array in the parameter?

[@sheraz_razzaq]

Thank you.. Sir....

[@vishalrao5541]

nothing understandable

[@pvssandeep2836]

Thank u sir

[@ArshdeepSingh-nm1tt]

i donno why he took that pause 0:02 , anyways he's best!

[@laxmig7764]

Explain examples sir

[@aadarshmishra1488]

mja aa gya sir

[@RHIN0o]

thanks for this video!