Lecture 66: Construct a Binary Tree from InOrder/PreOrder/PostOrder Traversal

In this Video, we are going to solve TREE Important Interview Questions.
There is a lot to learn, Keep in mind “ Mnn bhot karega k chor yrr apne se nahi hoga ya maza nahi aara, Just ask 1 question “ Why I started ? “
Discord Server Link: / discord
Course Flow: whimsical.com/dsa-4-placement...
Notes Link: drive.google.com/drive/folder...
Slides Link: drive.google.com/file/d/1HQBc...
Code Links: github.com/loveBabbar/CodeHel...
Questions Links:
- Construct a BT from Inorder/PreOrder traversal: practice.geeksforgeeks.org/pr...
- Construct a BT from PreOrder/PostOrder traversal:practice.geeksforgeeks.org/pr...
Do provide you feedback in the comments, we are going to make it best collectively.
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My Editor: rishu.rsing...
Intro Sequence: We have bought all the required Licenses of the Audio, Video & Animation used.
Timestamps:
00:00 - Question 1
02:53 - Approach
11:05 - Code
22:38 - Question 2
23:40 - Approach
27:20 - Code
#DSABusted #LoveBabbar

[@srmtube2556]

3 things I learn when I see this videos one is dsa concepts and other is consistency and commitment.

[@inspiringzone12]

Absolutely right

[@khushisrivastava357]

Hey are u there? actually i am not able to find the codes on the github link after lec 65..i think they are missing

[@RohitSharma-vq7ro]

​@@khushisrivastava357bro itna to khud try kar

[@MSDHONI___]

consistency is important bro

[@top10shorts21]

The code mentioned in the video doesn't passes updated testcases --> So here is the updated code --> class Solution{ private: int Findposition(int in[] ,int inorderStart , int inorderEnd , int element ,int n){ for(int i = inorderStart ; i=n || inorderStart>inorderEnd){ return NULL ; } int element = pre[index++] ; // At every interation index is increasing Node* root = new Node(element); int position = Findposition(in , inorderStart , inorderEnd ,element, n); root->left = solve(in , pre , index , inorderStart , position-1 ,n); root->right = solve(in , pre , index , position+1 , inorderEnd ,n); return root ; } public: Node* buildTree(int in[],int pre[], int n) { // Code here int preorderindex = 0 ; //Pre order is NLR so First element is root . Node* ans = solve(in , pre , preorderindex , 0 , n-1 , n ); return ans ; }

[@sourabhvishnoi9884]

Really helpful, thanks

[@anmol3]

Thanks

[@vimalrai2092]

it really helps, i was soo confused. thanks...

[@AmitSharma-nv2oj]

@@vimalrai2092 for which question

[@khushdesai7600]

can u tell us what you have change in this code?? because i have see this couple of time but , i could not catch it??

[@anmol3]

Question 1 Test case 54 fails after addition of new test case Solution: Can't use maps. Use findPosition function and pass inorderStart and inorderEnd as arguments and not n(size). This happens because elements might be repeated.

[@yashbanka8877]

There is something wrong with this concept let me just clear it up . When you check for the location of the element in the inorder array you need not check it's location by traversing in the whole array instead , you need to check for the element in the required portion . In this case check for the element from in[inOrderStartIndex] to in[inOrderEndIndex] and you will just be fine

[@shwetpatel2712]

Thanks Bro it works.

[@PriyanshuSrivastava11fig]

@@shwetpatel2712 please share the updated code. I'm not able to figure it out how to pass 54th test case using map

[@shwetpatel2712]

@@PriyanshuSrivastava11fig sure here it is. class Solution{ public: int findposition(int element , int in[] , int start , int end) { for(int i = start ; i = n || inorder_start > inorder_end) { return NULL; } int element = pre[preorderindex]; Node* root = new Node(element); int position = findposition(element,in ,inorder_start , inorder_end); preorderindex++; root->left = solve(in,pre,n,preorderindex, inorder_start , position - 1); root-> right = solve(in , pre , n , preorderindex, position + 1 , inorder_end); return root; } Node* buildTree(int in[],int pre[], int n) { int preorderindex = 0; Node* temp = solve(in,pre,n, preorderindex, 0 , n-1); return temp; } };

[@praveshishere]

bro what would happend if elements are repeated in between inroderStart and inorderEnd

[@anuragpandey8165]

30:15 You clearly have a strong understanding about where the students could get stuck. Much love

[@aayushiagarwal8797]

Thank you sir :), for making tree simple and understandable . I would like to highlight one point : Mapping solution will give wrong answer in case of duplicated nodes..... in such case , we can optimize findpos() function by checking from inStart to inEND .. int findpos(int in[],int x,int n,int s,int e) { for(int i=s;i

[@ritikrastogi6438]

Yes you're right

[@govindsuryavanshi6653]

First I have completed all DSA series and now conclude this is Greatest ever DSA series to exist on youtube or paid courses. Your contribution will be remembered. You're God of DSA for us🙇‍♂ Thanks you.

[@rishiagarwal813]

bro 65th lecture ke bad GitHub par code links nhi hai ky ??

[@prerakagarwal5623]

You are doing literally a very good job. I got to understand many concepts easily after watching your videos. Trees are very well explained. Many Thanks.

[@kritarthtripathi9793]

Best DSA course and consistency ++...Thank u so much for your effort❤

[@simplesolutions2621]

Best course! Best teacher! *Best time to learn!* 🔥

[@sudhanshukumar3976]

mid course me kon coad dana band kar data hai ghanta best teacher

[@prashantbirajdar9271]

wah bhaiyaa ..another an exciting session i understood every thing from this session thanks bhiyaa for providing free of cost DSA course...loves the most...content and your teaching technique is so optimistic...thanks again

[@yadvibhalla5392]

Best course ever🔥 consistency++;

[@pavanmutalikdesai6611]

Best explanation!!! You make solutions look so simple.

[@chandrabhanbahetwar9638]

It is the best dsa course in the you tube bhaiya carry on we all are with you 🌹🌹

[@rampratapmishra5962]

Wahh... Bhaiya mann gya aapko.. Kya consistency ha aapkee.. Ham ek video dekh nhi paarahe.. Aur aapke... New video... Aa rahe.. Ha bhaut saahi bhaiya.. Bass.. Aise hee consistentsy ham bhi continue kar paaye... Great bhaiya really great fan of you!!!!!! 🤗🤗

[@ayushkiledar4730]

Awesome!! The best DSA anyone can teach!!

[@prabhatmishra6753]

Great Efforts Sir....I think who wants to learn tree this is the platform

[@ritendrasinghbhadauriya5751]

Sir apke efforts to wakai sir excellent and ek aur best cheez ki aap scratch se har cheez samjhate hai........and sir salute to your consistency........💯💯

[@ayushjangid5649]

One of the best teacher || mentor. Thank you so much bhaiya for this course literally the best course.

[@nishankdas1895]

Amazing observation bro on the inorder to postorder question. I have never thought it that way.

[@KPCoder]

Thanks you sir, excellent content, no one can explain like you from basic 🙏 god bless you

[@rohanyadav2056]

Sir many many thanks to you You're an inspiration , I've referred this playlist to all my friends. Your dedication is next level sir

[@haiderali0801]

The best DSA course ✨❤️

[@scoc55vora15]

A Very WELL EXPLANATION wala Video and Insane amount of Effort of Love Bhaiya is clearly vivble and For that Again and Again Explanation Thank you bhaiya

[@ankitgaur7428]

Bhai Lecture 66 onwards code ko github mai push kyo nhi kar rhe ho? Repo se code samajna easy rehta hai. during videos hum code samaj sakte and then after completion of video hum code repo se notedown kar sakte hai. so pls push code from lecture 66 onwards in github repo.

[@fahadnazir8924]

is Source-code of lecture 66 onwards available anywhere ?

[@shrajangupta8206]

did you got any sourse where codes are there this lecture onwards?

[@harpratapsinhnakoom3540]

words are not enough to express our gratitude towards you.. Thank you bhaiya

[@Amaan-ji4su]

Best DSA course on youtube !

[@shivkumar-og4ow]

thank you bhaiya .. you are doing regularly hardwork to complete this course .. bahut bahut dhanybad.. ❤💘💘💘💘

[@iqfacts8647]

Best dsa course I have ever seen

[@ritikamehta9791]

Great consistency sir💯💯. Thank youu vry much!!

[@AA-wy9vw]

Loving the series!!

[@satwiksharma4359]

Great series , very helpful .

[@anuragmalviya2397]

Bhaiya ki knowledge, video uploading me consistency, or way of explanation top notch hai!🔥🔥🔥

[@user-lk1jv9qv4s]

Totally agreed

[@vinayakgarg4628]

Here we can also use unordered map (T.C - O(1)) as we don't need data to be sorted, so the overall t.c will be O(n)

[@deepakpal2168]

Bro it will not work if we have dublicate values in array like (1 2 3 4 3)

[@himanshukashyap8894]

keep growing bhaiya. You do wonderful for us

[@someshsangwan3768]

Op consistency bhaiya 👍🔥🔥🔥

[@rashmi_gaur]

Awesome Explanation!

[@aishwaryaporwal2321]

I just solving this question from ur DSA sheet n got this video notification ♥️♥️💯

[@faizanalam8360]

Loved your efforts. Thank you bhaiya

[@ani68]

Was waiting for this one......💯💯💯💯

[@shaleenspeaks003]

The best best best and best course ever

[@dewanshpatle9056]

Best course ever consistency++;

[@siddharthyadav1885]

great work and effort

[@prateeksharma3680]

Attendance marked 👍👍👍 consistency 🔥🔥🔥

[@ShailendraSingh-ob7rp]

Thank you bhaiya Maza aa gya questions solve krke ✌️✌️

[@parassetia4964]

Lot of love to you bhaiya, hope you are well and fine. Just waiting for graphs and dp too😅

[@utkarshsingh1457]

consistency op... Thanks for the beautiful content...Just enjoyed going through the lectures one by one... 😁

[@deepak44222]

mehnat lag raha hai bhai tum enjoy kaise kar le rahe ho.🥺🥺🥺🥺

[@uditpanjiyar3203]

first question is explained very deeply but one more condition is also added on gfg that the values of root can be repeated thanks for the quality content

[@ritesh_tiwari447]

for repeated nodes Just use map mpp and find element index by using {mpp[element].front()} then pop the queue

[@KratosProton]

Great explaination!

[@RahulKumar-wt9qc]

Shaandar video hai bhaiya 👍👍👍

[@keshavgambhir9894]

Present bhaiya Consistency op 🔥🔥🔥 Commenting for better reach

[@suvigyabasnotra7378]

Can you give advice on what to do after seeing the solution of a problem you've never seen before and don't know how to code..?

[@SanjuJana-pj6pn]

Thanks a lot bhaiya 😊❤

[@rohitrohra7553]

u make everything simple

[@shekharsuman3219]

Bhaiya keep inspiring us we r with u

[@muhammadsuleman8936]

Lecture was amazing brother

[@curiosityOnItsPeak]

I used to get scared from some of questions including these But now .....Huhh! . All thanks to you bhaiya

[@ekanshsharma1309]

Simply Love You Bhaiya 💗💗

[@gauravverma4652]

in first question u used map for optimisation which have complexity O(logn), shouldn't we use unordered_map for O(1) complexity ??

[@Coder_DhruvArora]

Yes

[@sahilchhabra2391]

bhai dono me O(1) hogi na. Map ki key already pata h toh value toh yuhi nikal jaegi aur mp.find() use krne ki need nhi kyuki map toh bana hi saari entries se hai, key toh pakka hogi hi.

[@Coder_DhruvArora]

@@sahilchhabra2391 I didn't got your point But even inserting into map also takes O(log n) So it definitely adds into time complexity

[@sahilchhabra2391]

@@Coder_DhruvArora oh I forgot about the insertion complexity for ordinary map 😅, ya ya u got that right

[@7u5h42]

🙌🙌 consistency OP

[@kunalbhika6424]

Great lecture as always😍

[@rishabhjain7838]

Dedication 😱💯💯

[@amishapandey6875]

Really THANKFULL!

[@laksheybanga8106]

Mzaa aa rha h bhaiyaaa 💕❤️

[@Urahara25]

One suggestion bhaiya... We don't wanna get demotivated...so contest ke bhi solutions practice krwaiyega please......And company specific category bhi ki like kis site se kaun si kaun si company specific pdhna h... Interviewbit ,gfg,...etc...Amazon, Microsoft,google nd aur bhi

[@harshpandey4190]

Thankyou So much bhaiya going great

[@alokranjan3185]

great explanation sir❤️

[@niteshkoli007]

ab ye question mai kabhi bhi nhi bhulne wala😁

[@sunny-gb6xh]

Thank you bhaiya for your grt content :)

[@janvi_jindal05]

you are the best bhai....

[@user-ey9lq4mf6p]

Thankyou Bhaiya!!

[@adgurjar1663]

Best course 🔥🔥

[@ziyadauti3676]

Best explanation compared to others...!

[@Harshit-rm5kd]

Thanks a lot bhaiya ❤❤

[@user-ks8qn5sz5b]

code link from 66 lecture to end is not available sir , plzz upload the link the of code link. thank you from the bottom of my heart sir for making a beautiful series for us 😍😍

[@yashzawar7938]

great job!!

[@RajKumar-vq1nm]

Maza agaya..❤️

[@RohitKumar-rm3kc]

Amazing video 💛💛

[@SanjuJana-pj6pn]

Thank you sir 😊

[@bhavooksethi2589]

Best course❤

[@PRIYANSHUKUMAR-un9zu]

Present bhaiya🔥❤

[@adarshparitosh5870]

Thank you so much bhaiya, before it I have been read 2,3 time but my concept was not clear but in first attempt I got 100℅ understanding of construct tree, ab mai DS se diprate ni ho rha😃ni to 4th sem me aa kar lgta tha khi CSE le kar galti to ni kr diye...

[@theguywithdreams1600]

Thankyou Bhaiya ❤

[@AyushKumar-yu5tj]

After this course Knowledge will be like knowledge= INT_MAX;

[@BicornOfficial]

lecture 66 onwards, the codes are not available on the github link mentioned in description. Where can i get those codes, does anyone have any idea?

[@simplesolutions2621]

Love _Consistency_ Babbar!

[@sailendrachettri8521]

so far so good :)

[@utkarshverma8773]

ULTIMATE CONTENT

[@aryapatel3495]

awesome video❤

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Deadline Seriously Le Rhe Ho Kya Bhaiyya😂 Consistant Level OP😁🥰

[@Sam-rz5hw]

bhaiya aap best ho

[@manishFromIT]

Thanks bhaiya 👌

[@swapnilsalunke5942]

Great work

[@mansoorrr9167]

Can some tell me how in root left and right after giving range positions it is extracting the elements from inorder array? We are only finding the position of element from in order arr and passing the positions to recursion but how it is allocating the root left and right from the I order arr??

[@yashgupta4866]

Present bhaiya Consistency OP

[@savy9554]

Amazing content

[@harshalpatil6482]

east or west babbar bhaiyya best

[@bhuvamehulkumarvisabhai2904]

here in solve function why we sent map by address, because i try to sent by value and it gave me TLE

[@verma_jay]

best course

[@mightygerman]

Thnx a lot sir....

[@shubhammanitripathi9507]

Maja aa gya 😁😍