Binary Tree Bootcamp: Full, Complete, & Perfect Trees. Preorder, Inorder, & Postorder Traversal.

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Full Binary Tree: Every node (besides children) has exactly 2 children (the maximum children a node can have in a binary tree).
Complete Binary Tree: Every level, except possibly the last, is completely filled, and all nodes are as far left as possible.
Perfect Binary Tree: All interior nodes have two children and all leaves have the same depth or same level. Perfect binary trees are both full and complete.
Preorder Traversal: node left right
Inorder Traversal: left node right
Postorder Traversal: left right node
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[@BackToBackSWE]

Table of Contents: A Quick Message 0:00 - 0:31 What We Are Going To Do 0:31 - 0:52 Full Binary Trees 0:52 - 1:38 Complete Binary Trees 1:38 - 2:14 Perfect Binary Trees 2:14 - 3:18 Let's Discuss The 2 Fundamental Traversals 3:18 - 3:42 How To Know Which Traversal Is Which 3:42 - 5:05 Think of Recursion Like This. 5:05 - 5:33 Preorder Traversal Walkthrough 5:33 - 11:15 Inorder Traversal Walkthrough 11:15 - 14:25 We Realize That This Is A Special Tree 14:25 - 15:07 Postorder Traversal Walkthrough 15:07 - 18:59 Briefly Addressing Time Complexity 18:59 - 19:22 Wrap Up 19:22 - 19:40 At 1:42 I meant that binary heaps are complete binary trees with the heap ordering property. Not that a complete binary tree is always a heap. The code for the traversals is in the description. All recursive and basically the same function. We will do iterative and O(1) space traversals soon.

[@2WARDEN2]

The ToC and video itself are perfect! The quality of information is phenomenal, I'm glad I kept digging for pre/in/post order examples until I found this! Thanks for taking the time to create this!

[@BackToBackSWE]

ye, for the internet yo

[@bonniwanamaker6296]

This guy is an amazing teacher.

[@BackToBackSWE]

i try :*)

[@connerjensen8170]

Yeah for real I love his enthusiasm

[@SquidBeats]

Jesus Christ is God and is the only way. Hell is real whether you believe it or not

[@JossinJax]

Omg writing "lnr" at each node really clear this up for me. Thank you!

[@BackToBackSWE]

nice

[@oasishusband5260]

Ikr I loved that!

[@More-right-rudder]

I am a software engineer for 2 years and I didn't know that. Let me go sell my degree ...

[@alexandergonzalez5975]

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[@BackToBackSWE]

haha, what a statement

[@andrews2945]

*Ocean of low quality CS channels

[@Moitaytay]

I've gotta say; I've worked at Amazon and Lyft, where you'd think people have their fundamentals down like crazy, but they can't explain simple topics like these. You, sir, have the gift of teaching. Thanks for your help!

[@BackToBackSWE]

sure

[@prashmokk6659]

This video was amazing. I don't really comment on videos, but I had to express my appreciation to you for creating this. I got an interview about a month ago and this was the first of many videos I watched of yours while I was preparing. This past week I found out that I got the job and you were a big part of that. I'm not sure if you'll see this, but I hope you know that your videos have helped me and many others. Please continue to make awesome informational content like this!

[@backup2ramdisk]

WOW. Watched a bunch of videos by different people on traversals, everyone else just mumbles on and on "print this, skip this and print that" without explaining why, and you're THE ONLY ONE who actually explains the whole recursion thing in detail. THANK YOU SO MUCH!

[@swimmingbyrd6283]

Showing these traversal with a "n" saved my lllliiiifffffeeee!!!!

[@BackToBackSWE]

yuh

[@gauravpandit577]

Wow the Video is Awesome, I had studied this in my College but never understood it, But now its crystal Clear Kudos to you...!!!🤗

[@BackToBackSWE]

great

[@MM-lo9tk]

I always assumed this was a super complicated topic and have been putting it off as long as possible. You just made it so simple and easy to understand. Thank you. I think I just found my new favorite channel!

[@sunnypatel1784]

Your reaction to the cutting and the stomping sounds cracked me up! Great content man! You just got yourself a subscriber.

[@artyomkarapetyan08]

This is amazing. I've tried watching 5 binary tree videos and none were as good as this video! It's just so clear and everything makes so much sense and I can feel this concept internalizing for me. Thank you!

[@mhaland2775]

I have looked at so many videos to understand this. This is the first video that made me understand it:) The recursive way of thinking was really helpful to understand this

[@BackToBackSWE]

thank you! Means a lot

[@manojchoudhary6146]

I don't know who's those people who dislike such informative video. Great efforts, keep doing.

[@crewelghoul]

I've been struggling with data structures and algorithms, and this really made things a lot clearer, thank you so much!

[@BackToBackSWE]

great and sure

[@haylydo8376]

I never comment on videos I see, but this one has to be the exception, because this is by far the best video I have seen on this topic. It cleared up so much confusion, and gave me tools to use along the way. Thank you!

[@BackToBackSWE]

Nice to hear. Thanks and sure

[@fanifyeyev]

I have watched dozens of similar videos, I can tell you, this guy is amazing. The way he provides the material is unbelievable, so motivated, so much energy, so much positive things can be felt.

[@BackToBackSWE]

thanks - this guy

[@andreysantos6660]

Man, I wasn't being able to understand tree transversals properly until I've seen your explanation. Thanks a lot! Now I understand!

[@BackToBackSWE]

nice!

[@birbx3r354]

I struggled with data structures and algorithms for 4 years. Watching your vids has helped me finally understand what's actually going on in layman's terms. Thank you so much for making these videos and keep it up!

[@BackToBackSWE]

ye, great

[@marilu0007]

The only person with charisma to teach Data Structures, I love it! (mosh is also good but you are pure gold)

[@johnisdoe]

This video is VERY helpful in understanding recursion. I honestly brute forced recursion and never thought of it that way. As someone mentioned in the comments, this channel is a one-in-a-million!

[@BackToBackSWE]

great

[@gloriawang7493]

thank you for such a high-quality video. your explanation of "each node needs to execute the same policy" makes a ton of sense! never have i understood traversal so clearly until your video!

[@josephwong2832]

The way this guy walks through these examples is crystal clear.

[@BackToBackSWE]

ye - this guy

[@travissimelane1847]

I don't know how to thank you. You have saved me hours of reading a Data Structures Textbook 3 times just to get this concept. Very thankful. Please do not stop your great work

[@shenzheng2116]

I am a math student targeting for a data science career And I have to say this is the BEST computer science video I have even seen! Just AMAZING!

[@BackToBackSWE]

thx

[@alexbowen3381]

Thank you so much for this video!! I'm an MIS major and a former CS major and after a so many CS courses a 20 minute video by you finally made me understand traversals! You are great at explaining these concepts and I look forward to binging more of your lessons as I brush up for some SWE interviews

[@BackToBackSWE]

nice thx

[@vamsishankar2825]

I used to not watch this channel and ignore this channel, as it is also a channel which offers course like tech lead, joomla and others. But after watching this video, I subscribed to your channel for the most intuitive explanation given on Preorder, Inorder, & Postorder Traversal and really Loved the content.

[@BackToBackSWE]

Yeah, I think we are pretty good. We have a dedication to what we do and are looking to create a service & brand with longevity and the intent to augment people's lives. I think that is something that can stand the test of time.

[@dansteryoo]

a lot of channels would have taken shortcuts to fast-forward or just breeze by each node explanation because it might feel redundant.. but man so thankful you understand repetition is an important part of education.

[@BackToBackSWE]

sure

[@iaminhridoy5871]

To be honest, you way of teaching is as clear as crystal, loved it ...

[@tmzpanda]

0:46 full/complete/perfect binary trees 3:48 preorder/inorder/postorder traversal 5:38 preorder and dfs 11:16 inorder and binary search tree 15:07 postorder

[@BackToBackSWE]

yes

[@xxlhara]

man, you've got some intense energy, i love it.

[@jorgeriveramx]

Thanks you man, great explanation. I have been a programmer for 11+ years, but never attended software engineering classes, just self taught, this videos help me a lot.

[@BackToBackSWE]

great and great

[@ftedg]

A channel like yours pushing quality CS videos is really really in need... Thank you so much for your efforts. Most of what's on youtube is low-quality Indian content (no hate). Again thank you so much and please dont stop! I would recommend some videos on Algorithm designs like divide and conquer, greedy method etc.

[@BackToBackSWE]

Haha, well I think my videos are "ok". I just want to do them and if it helps someone then all the better. If it completely goes over someone's head then that is fine too. Also, I think a table of contents in any instructional video longer than 4 minutes is key. Everyone comes to a teaching with different levels of preparedness and precontext. And in regards to the Algorithms stuff...we will do plenty of that just give it time since I have a long content list to cover. Those topics are in the list.

[@soumyajeet7809]

Lma4a Well i agree, that there's a lot of Indian content but u can't classify everything generally as low quality. I mean, since there are so many Indian channels, there's a good chance that the videos posted are not that good but there're some legit channels that if u learn from u definitely won't be disappointed. Instead u'll thank me later. See the videos on the channel "mycodeschool" and u'll know.

[@huilingyan3981]

I do have seen good quality Indian content videos. The thing is that as a non-native English speaker, i always have to spend extra time understanding what they said lol

[@emilyhao9272]

@@soumyajeet7809 Disagree. All of the content I encountered have been a waste of time. What's even more frustrating is some often switch between English and other languages, highly confusing for the viewer. Just make two videos or stick with one language and subtitle it.

[@soumyajeet7809]

@@emilyhao9272 Here are some Indian KZbin channels that offer their videos only in English and the quality of content is excellent. You should have a look at these. If you still find these a waste of your time, try learning from books or other channels. 1. Edureka 2. Intellipaat 3. Simplilearn 4. ProgrammingKnowledge 5. Mycodeschool 6. codebasics 7. TutorialsPoint India ltd

[@ParsPersianVR]

to the point and straight! thank you! in preparing for my qualifying PhD exam and i just arrive after work and come to starbucks to study! i dont have enough time to read allthings in book carefully so thats the reason this video save much more time for me! tnx again! :)

[@yannickwessidjam2036]

Wow! the best video I have ever seen!. I have been trying to understand this for so long. No one really explained it in a format that made sense to me. This makes so much sense!. Thank you !!!

[@abhilashp4439]

His reaction to the loud cutting noise was hilarious!!

[@BackToBackSWE]

Happy Holidays 🎉 Haha Thank you for your comment, Abhilash! We'd love to offer you a 40% Off our exclusive lifetime membership just use the code CHEER40 - backtobackswe.com/checkout?plan=lifetime-legacy&discount_code=CHEER40

[@bufdud4]

Wow, I was struggling to visualize recursion for months. This cleared it up for me! Thank you!

[@BackToBackSWE]

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[@MikeChaseJr]

This is amazing. One of the better CS videos. I love how you ask questions to test our understanding as we watch!

[@BackToBackSWE]

ye

[@sasbazooka]

I'm a Sr. Software Development Engineer who got here without ever taking any CS courses, and now I am hurting for that. This dude here is giving me the exact info I need to fill in the blanks. Bravo dude!

[@BackToBackSWE]

Thank you, appreciate it 😄 Also check out our Free 5 Day DSA Interview Prep Mini-Course - backtobackswe.com/ 🎉

[@nitingupta1591]

The best traversal video till now. You teach using first principles. Hats off !

[@safsofapeintor2249]

I rarely comments in videos but your videos really deserves more then comments and likes , I hope u continue sir with such amazing content

[@juliannafotheringham7101]

This is the most fantastic, clear video I have ever seen on DFS traversals, thank you so much my dear angel!

[@beverlykwok9704]

this channel is sooooooo underrated... truly the best coding teacher on youtube

[@BackToBackSWE]

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[@kakashisenpai99]

This guy is the best Teacher 😍

[@BackToBackSWE]

im ok

[@kakashisenpai99]

@@BackToBackSWE 👍👌

[@bartlomiejdrozd2357]

Great stuff my friend! Way you use NLR, LRN, NRL is simply beautiful. Few minutes and I got to understand how binary trees are traversed! Thank you!

[@BackToBackSWE]

ye - great - sure

[@drodskate]

This is exactly what I needed! Thank you so much! You have no idea how hard the summer quarter has been with the lack of explanation.

[@BackToBackSWE]

nice - happy 4 u

[@jonathanluo0]

5:24 explain very well on nlr (Preorder) traversal on each node, plus recursion in general

[@maxstanley1818]

two years later, hands down best traversal video on youtube.com. I don't know why schools do not use the nlr rule

[@gansaikhanshur4934]

Who's watching this in 2022. This guys know how to teach!!! Thank you!

[@tobyhuynh146]

dude, your explaination helps me retain the information so much better than other tutorials. writing the policy on each node is a really good trick for a visual learner like me. Thanks

[@BackToBackSWE]

glad it helped

[@cesare-o7l]

Hey Ben, someone posted your channel on /r/cscareerquestions and from that moment I'm hooked to your videos! Thanks so much for making these videos. I'll have my Twitter internship onsite in two days and your videos are helping me to brush up.

[@BackToBackSWE]

hahahahah, so THAT's why the channel growth spiked one day. I was so confused. What was the thread? And thanks, yeah, this channel has a long long long long long way to go.

[@cesare-o7l]

​@@BackToBackSWE Haha the guy who posted it actually removed the post contents with the link when I last checked. I don't have the link though. It definitely had more than 50+ upvotes

[@BackToBackSWE]

@@cesare-o7l wow...yeah I've been bugging the moderators for a post. They are definitely sleeping on me. That's why I think I have a ways to go. I need to wake them up.

[@Danny1905]

Awesome. I came from a great CS book I'm reading and the chapter I'm right now touched this topic, so I came here for more info and wow. You helped me to understand it so much better! Keep it up! This channel is awesome

[@BackToBackSWE]

thanks

[@reinasama904]

The quality of this material is beyond what we deserve THANK YOU SIR

[@ichinnorovtuguldur3627]

I like how he teaches it so passionately. It was super helpful! awesome!!!

[@BackToBackSWE]

thx - and great

[@srinadhp]

The way you explained the recursion is class apart!!! Also how to identify pre/in/post order. Hats off. Will now search for your video on graphs! Hope you have it. Keep posting!

[@BackToBackSWE]

thanks and ok

[@jonathanberkeley4109]

you are a good teacher, thanks for the video

[@BackToBackSWE]

thanks sure

[@caleboke2771]

Using LNR as the call stack just help me understood how binary trees work in general. Thumbs up man

[@brucewayne3141]

I study CS at an Ivy League school and I didn't learn shit from my professor's lectures. Your videos are literally saving my grade cuz my final is tomorrow. Thank you.

[@aleksascepanovic4773]

I dont like ever comment on youtube, just wanted to say thank you.I didnt attend my classes for 2 months due to health issues and was having trouble understanding this going only by code and presentations I had.Thank you, again.

[@faridashaikh1015]

lnr at every node just made things so clear for me .....This is just amazing!!!

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All videos on this channel make my concepts Crystal clear

[@BackToBackSWE]

nice

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Honestly, You did a wonderful job explaining this content! It was fun, easy to follow and understand! 5 Stars! I did watch all of it, and I shall continue too watch all your videos! You rocked it!

[@BackToBackSWE]

nice thx

[@mattdoestechstuff]

This was really helpful. My university lecturer did a terrible job explaining this, but you managed to do it so succinctly and clear. Thank you!

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Nice job, you are making Africans very proud of your content. I'm sure your Ethiopian/Eritrean brothers and sisters agree.

[@BackToBackSWE]

Great haha though I think everyone should just do whatever. I don't want to inspire one group (though great if it happens). I'm just human, I just see humans.

[@persnlassname7137]

Thanks to your channel... It really changed on how I see the traversal works, I understand it better and I hope I can pass my midterm exam on this topic. Thanks dude

[@BackToBackSWE]

nice!

[@konekoshoujo]

Bachelors in CS, 3 YOE and this is the firs time I understood recursive tree traversal! thank you!!

[@diveruzumaki5556]

after three years I finally understand tree traversal properly T_T , THANK YOU

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This is AMAZING! And I laughed so hard at *LOUD CUTTING NOISE*! (Probably means I need to come out of my office for a bit lol) I for sure will be using this content for preview of whatever I am learning. Great work!

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This video is gold. Thank you!

[@BackToBackSWE]

sure

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I love you for providing these insights. Can't stress enough how much this is helping me, man!! Thank youuuuuuuu❤

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[@BackToBackSWE]

thx

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Bro, you are the be(a)st, very intuitive explanations. I am not a cs major, but I can follow you very well. Please keep up the good work.

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After watching this video, I laughed at myself on how struggled for nearly 8 hours with this concept you just made easy within minutes.

[@BackToBackSWE]

ur good

[@iulia6707]

this helped me a bunch for my collage exam, thank you!

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[@BackToBackSWE]

Thanks! Germany is sweet!

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Dude I wanna say that you are really impressive. This subject really made me confused but with your teaching style that shit became more understandable. Thx so much.

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[@speedsanti]

It’s hard to keep up and stay motivated with online classes, so I started slacking off in my data structures class. Thanks to you, I feel like I’ve caught up and I feel ready for my midterm on wednesday 😼

[@BackToBackSWE]

great

[@jacobmoore8734]

Studying for an interview next week, wasn't a CS major. OP, you're an awesome resource!

[@BackToBackSWE]

u gon make it

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Quality breakdown. Simplified, easy to understand. Much gratitude! Man, even very easy means of memorization. Fantastic.

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God bless you brother. Your style in explaining things is sensational

[@BackToBackSWE]

thanks and thanks

[@GGphantom1031]

The best American English video to explain the binary tree lesson I am learning in college so far ! T.T ...

[@BackToBackSWE]

Hey

[@codepractices7]

Amazing content and teaching!! Gained so much knowledge in 20 mins than i could in my whole semester!! Please continue making such quality content on DS&Algo!! Thank you Ben.

[@BackToBackSWE]

nice

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Absolutely well explained. I am watching this before my google interview tomorrow. Thanks a lot! Subscribed!

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This is the best explanation I have heard so far. I cannot forget this!

[@BackToBackSWE]

thx

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I can NEVER forget this

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[@BackToBackSWE]

haha

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first time I ever subscribed to a channel after watching just 1 video, you have a great teaching style!

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[@BackToBackSWE]

It is indeed...it is indeed.

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[@BackToBackSWE]

great haha

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[@BackToBackSWE]

sure

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Awesome! Thanks for this video. I was just attempting a leet code problem where I had to traverse a binary tree and I was pretty lost. You're a great teacher!

[@BackToBackSWE]

sure and thanks

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best explaining I've seen so far. Thank you so much!!!

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[@BackToBackSWE]

ok

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[@BackToBackSWE]

ok

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[@BackToBackSWE]

thanks

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[@BackToBackSWE]

thanks

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Man this is the best explanation of tree order/recursion that I've seen great job!

[@BackToBackSWE]

Thank you, glad you liked it 😀 Do check out backtobackswe.com/platform/content and please recommend us to your family and friends 😀

[@frozen_tortus]

Absolute hat's down. The teaching style is unique and I love it.

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[@BackToBackSWE]

Thank you, glad you liked it 😀 Do check out backtobackswe.com/platform/content and please recommend us to your family and friends 😀