It took me a week to finish this tutorial. This tutorial is just pure gold. I always found it hard to understand time complexity for recursive solutions. But this video explains it perfectly. This is probably the best tutorial on dynamic programming. I can't believe you're giving such quality content for free...
I am 45 mins in, but I had to stop to drop this comment. This is hands down one of the best tutorials I've ever seen. Alvin is a true teacher. I am blown away by his style. I have taken paid courses on this topic, but this is the first time I am understanding what this is about. I can't wait to finish this tutorial. I am going to go for all your courses.
I've been coding since 1998 and have watched countless tutorials on countless topics. This guy is definitely one of the best teachers I've ever come across.
my man Alvin! I'm a Senior Developer but it was always a grind to brush up DSA topics when I'm in the job hunt. Your videos helped me quantify it a lot. I just watch your DSA videos in 1.5x half a day before an interview and that is all I need. Very well put both for beginners and for folks like me who need a quick run-through. This is the kind of stuff internet is made for. Appreciate the great work. keep it up!
After getting frustrated from these dynamics programing, after hunting to know the real concepts in books, articles, online paid courses, CZcams videos, finally got this here and that too free. I can't believe this. He teaches like crazy. Thanks a lot.👍
Damn this guy was the instructor for app academy. His explanations actually put me on the track to understanding this crazy world of code. So glad he's back on the scene!!!
a note: go donate on their website, it's tax free (As they are non profit), they get the full amount and you pay no taxes. CZcams charges taxes to both the channel and the donator.
This is the slickest way I've ever seen not only Dynamic Programming, but also recursion presented. His slides/animations are just perfect for guiding every single step your brain needs to go through along the way, and he handles all kinds of gotchas and keeps you from getting stuck. I'm already going from "holy cow how am I going to even approach these problems" to "ok this is starting to get intuitive with this workflow" just an hour in. Literally better than any professor's teaching style than I remember from my college CS program. The effort put into this video is insane! I have a feeling this video just covers some of the basics-intermediate problem types, but I bet this will be a great stepping stone to tackling the harder DP problems.
Phenomenal teacher, I’ve got an hour left and even though I’ve fumbled my way through similar problems I feel I understand everything much better. This is now my go to recommended video for recursion and dynamic coding
I'm here after watching graph algo. I am a data engineer and I always struggled to understand the space and time complexity, this animation is all I ever wanted. This is by far the best video I watched on dynamic programming. Moreover, Alvin has that charm to keep me captivated for long hours without loosing focus. Keep up the great work man!
I've never seen anyone before who was able to better and more clearly explain dynamic programming. The way you're leading us there step by step and also how the material is presented is outstanding. I'm very impressed Good Sir :-) Thank you very, very much 🙇
@@khz2172 I don't think he's that good, the course only teaches the basics and some simple problems. If you want to become good at DP I think you should practice with some DP problems (from codeforces, for example)
I'm not one to watch any 5 hour video but this one really hooked me to go all the way. Explaining hard things in a simple and engaging way is hard and you delivered it perfectly.
Brilliant video! The entire community of learners owes you a coffee for teaching us this excellent approach to solving the infamous dynamic programming problems. Other videos and books do not go into this well-defined mindset and step-by-step strategy that you need to develop, in order to understand and ultimately solve these problems from a *pragmatic* approach (which is what ultimately aces technical interviews). Keep up the great work, Alvin!
Simply THE best dynamic programming course on youtube, wonderfully explained. The course made understanding the difficult concepts a breeze. Loved the progression of problems, even the harder ones felt easy after understanding the basic strategy and the recipe. Thank you freeCodeCamp and Alvin.
@@LogansDarling while I'd argue there are probably better, more direct ways to support a creator, what makes it so weird to you? People have been spending cumulative billions of dollars over the past years just for having their message read on stream or purely for support. It's basically a pay-what-you-want scheme. If you really feel like shaming other people's spending, I suggest you may start with people buying shiny rocks to put on rings with otherwise zero value and ethically questionable production.
@@TomasLKarlik while I'd argue that shaming someone for how they choose to support someone is lame, financially or otherwise, what makes you think that's what I was doing? People have been being confused by the billions of new features YT has put on their platform over the past years just because they're not used to it. It's basically a guess-what-this-symbol-means scheme. If you really feel like assuming the motives of peoples' questions, I suggest you may start with people sarcastically belittling people to cancel anyone who doesn't follow their exact position with otherwise zero value and ethically questionable means. jokes aside i understand how that could be misconstrued as an insult but i was genuinely wanting to kno cuz it could have been like idk - Spending money on a specific comment. - Spending money on a channel. - Spending money on YT. - Spending money outside of the platform and the YTer giving them the badge. - No money even being spent and me just thinking something is a currency symbol. - It could be _anything_ considering how stupid I am, so I have no clue. although if u kno that its for a specific comment then ig u answered me so thx (I do think that it's stupid, but that's more on YT's part than the commenter's part. Seems like a stupid feature to add on the platform, but that hasn't stopped YT before so oh well. ¯\_(ツ)_/¯)
Learning to code by myself, this course brought me so much. I didn't know anything about dynamic programming, not much about time and space complexity. Now I wouldn't say that i master it of course, but with those great explanations and examples I happened to cruise through all these exercises with ease. I am genuinely shocked to see how easy it is for me now, as those problems just seemed impossible before and their solutions looked like witchcraft. Thank you so much, this is a wonderful course !
It's amazing to realize that grid traveler problem sounds like a completely different problem to fibonacci, but it's solved with the same pattern. Just wow.
You will find in theory of computation that the problems are divided into sets of similar problems ie we can reduce any problem to any other problem to solve and if we can solve just one problem in that set in an more efficient time complexity then we can solve other problems in that set the same way
Wow. Dynamic programming looked so daunting on the outside. In a matter of 2 days, you changed my mindset about it for good :) Now it seems easy and doable. Many thanks!
Thanks for the great content. In gridTraveler problem, base condition could be that if either of rows or columns is 1 , we can return 1 So, if(m == 1 || n == 1) return 1; And i think we could just check m and n interchangeably : if ((m + "-" + n) in memory) return memory[m + "-" + n]; if ((n + "-" + m) in memory) return memory[n + "-" + m]; As number of ways to travel a grid for (2,3) will be same as number of ways in case of (3,2)
This is the best dynamic programming content I've ever seen. What I found particularly helpful is being able to understand and view recursive problems as a tree. Because of course trees are recursive data structures. When you have a tree from the outset, as long as you understand general principles of DFS and BFS, a lot of solutions become obvious. What this guy does is show a way to make the implicit, explicit. It's that step that is usually the most difficult because sometimes you're just given a number and asked to solve the problem. Once you understand that problem with that starting value represents a tree of decisions, it allows you to visualize it in such a way that the solution becomes evident. Great job.
@@user-wl5tv4jl7v it's not a scam but they are definitely over priced. I think of college as my source for what I need to know, and the internet (mainly youtube) as my source of knowing those things. Without college/universities, it's hard to know what you need to know. It would take a lot of asking questions and bothering people who didn't sign up to be questioned... lol
I usually can't symphatize with ppl who say this, but yeah, DP is probably the biggest thing the internet has been able to taught me better than a price-near-the-seven-hundred-thousand-colombian-pesos uni course.
YOu should be given an award as the best tutor on Dynamic Programming concepts in the history!!! You approach is so detailed and step-by-step. You found the best formula on how to teach these complex things. Thank you very much for your job!!!
00:00 Intro to dynamic programming 3:22 Understanding the need for Dynamic programming 10:48 Understanding time complexity and space complexity 22:27 Back to the need for dynamic programming with an example 23:31 Dynamic programming - how it reduces the time complexity 25:56 Implementation of dynamic programming using memoization 38:38 More problem
This is an amazing and helpful tutorial! For GridTraveler program, we can solve it analytically. Assume a grid with size m*n , then to go from the top left to the bottom right, the total number of step moving right has to be (n-1), and the total number of step moving bottom has to be (m-1), the overall total number of step has to be n-1+m-1 = m+n-2. Any particular path is an arrangement of steps of these two types of directions. Therefore, it is equivalent to say that if we have total m-1+n-2=m+n-2, then count the number of ways we can pick m-1. So the analytical solution is (m+n-2)!/[(m-1)!(n-1)!] , where ! means factorial
I watched this in just 2 sittings. The explanations are so clear and well laid out. A lot of repeats of course, but that's kind of a good thing in this case because it helps to get used to the topic. Alvin is an amazing teacher.
This course just proves that when you go through each minute detail of a problem in a calm and precise manner, while also hinting at the obvious even, a student is much more likely to pick up on the subject. Judging by all the other comments, slower people like myself are starting to get the concept. 🤣 Fantastic coure, thank you very much for uploading this piece.
I don't think it's about slow or quick, it's just that schools don't teach us how to think. They just cram crap down our throats and expect use to puke up rainbows.
The author did not include in the compute complexity the access of the memoized data. For the fibonacci, the algorithm can be optimized to o(1) instead of o(n).
Thanks for the fabulous course 👏🙏One modification that I think the video needs is that for the grid travel algo with memoization, the space complexity is O(m*n) and not O(m+n) [1:04:15]. The stack of course uses O(m+n) space but the 'memo' object grows to store m * n key/val pairs. So the overall space complexity would be O(m*n).
one of the worst things about learning new DSA concepts is the jump in logic/thinking thats made where it doesn't make sense until you've done a million examples because people don't really explain their thought process and the intuition behind it much. this has none of those issues. this is probably the best DSA video i think i ever seen. amazing work, thank you. 🎉
This is hands down the best crash course on dynamic programming. After struggling for so many hours on dp, I actually feel that I understand the logic and process for tackling dp problems now. Thank you for this amazing video!
In the example of canConstruct 2:24:00 you can use the method `startsWith` since you're just interested in knowing if the target starts with the word, so you don't need to traverse the entire string finding the index! Amazing course btw I really appreciated!
Repent to Jesus Christ “We demolish arguments and every pretension that sets itself up against the knowledge of God, and we take captive every thought to make it obedient to Christ.” 2 Corinthians 10:5 NIV
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Man, Alvin, I watched your Graph Algorithms course first and I absolutely loved it! I saw people there, recommending this legendary course and I just knew I had to come here! Every single second watching this video was completely worth it! There is no way I can praise your explanation enough Alvin! There just is not! After this going through this video, I went from literally have no clue whatsoever about what dynamic programming even means, to completely falling in love with this subject. I would surely indulge myself into this subject, and I believe that this video right here is simply the best entry point for any developer out there who is willing to learn this subject. Thanks Alvin. I am really very grateful!!
Just thank you, for my job I need to write python code for some automation of processes, but I do not have a computer science degree so I kind of leaned on the fly. I knew there was a way of doing some stuff recursively but never tried because I feared it would take me too much time to understand and implement with my basic knowledge. Just with the firsts 2 examples I already have a pretty good idea of how to do it and I am pretty sure it will also help me in the future.
This is a great short course with a great teacher!! 😉😉😉😙 The classes I attended about dynamic programming in my university are not even comparable to this. This is much more understandable, well presented and makes you want to keep learning the topic.
This the best and most informative explanation of DP I've seen in 25 years! Great job and I hopefully some day you'll be compensated well for your outstanding teaching ability.
Very lovely tutorial. I finally feel confident about solving recursion and DP problems. I have a observation: At 2:32:27, why is the target.indexOf(word) === 0 not factored in, in the calculation for time complexity. Even though we are comparing against 0, target.indexOf(word) will first search through the word, which is (O(m)) before comparing against 0. This should leave us with an overall time complexity of O(n ^ m * m ^ 2).
You literally explained the course in a simple and legit way!! So, DP can be this easy??? 🏃🏾♀️🏃🏾♀️ me heading to leetcode to solve the hard DP problems!
After finishing this video in 2 full days, I am able to come up with an approach now, and write solutions. No matter how much efforts I made to learn dp, I was no where close to coming up with a neat approach. With these concepts and some more practice on the DP problems, I can sure be good as a hell pro problem solver in a month.
I've always been afraid of DP because of how counter-intuitive it can be sometimes. I also struggled with memoization and tabulation options. Thanks a ton for this video. Helped me a lot.
Definitely, one of the best courses to start with DP. Just started with the tabulation approach and, decided to attempt it after watching the initial explanation. But decided to follow a different approach as below: def fibDPTabulation(position): if position
Yeah, I wondered that too, why he's doing forward tabulation instead of backward one. But for the later problems with strings, it really makes much more sense to think forward, so he just wanted to establish consistent practice.
Alvin has made dynamic programming so much easier and quite fun to understand and code in. This video also strengthened my divide-and-conquer concepts, what a cherry on the top! Recursion tree explanation, animations, multiple examples and the way he helped to visualize how things actually work are just too good. My man also took things gradually, step by step and covered a lot without letting us get tired of it
Thanks for this tutorial: with your lectures I improved an algorithm that calculates any of level the Pascal's triangle, it was really satisfying to see the big improvement with a very few lines of code
Alvin I have been studying for months and i have taken my time through this video - single handedly drove home soo many concepts and helped me get a solid understanding and an easy translation into Python code. Thank you!
3:52:52 the space is actually the size of the largest value in the numbers array, (due to growing the array to i + num) which could be way larger than the target value (unless I am misunderstanding and the array becomes sparsely represented for a huge index so not memory hungry)
This is one of the best videos on both recursion and dynamic programming I've ever seen. Thank you for making this available and sharing this knowledge with the programming community.
It is always a treat to find content perfectly paired to one's journey in programming. For me, this content is exactly what I need. Thank you Alvin and thank you FCC for distributing! Unbelievable that this is free.
This is great, i love how it starts from a foundation and builds the muscles you need. I know the course is 5 hours, but I would have loved if it was even 20 hours just building up and up the core knowledge required to solve dyprog problems. I already feel better and more clear about recursion half way through.
Apart from the knowledge served, I also want to appreciate the work done to choose colours for slides. It works so perfect for both day and night mode.
@John Leal i was looking for this in the comments memoized base case after this optimization would look like if (m, n) in memo: return memo[(m, n)] elif (n, m) in memo: return memo[(n, m)]
Was wondering that too, I tried it out... Passing a grid of 500,500, I measured the time it took for it to run... 230ms without and 125ms with the sorting.
For the Fab why not this simple algorithm which is faster: def Fab(n): f1 = 0 f2 = ff = 1 i = 1 while (i < n): ff = f1 + f2 f1 = f2 f2 = ff i += 1 return ff print (Fab(62))
Because "i" has to iterate over and over until number "n" is reached, which means that the algorithm is based on how large or not is the "n" number, and when an algorithm depends of "n" numbers/items/elements/etc... the representation of it would be linear O(n), better than quadratic O(n^2) approach, not better than constant O(1). Hope I solve your question nabil, greetings!
You are a coding instructing master. There are millions of people who code, but only a few coding instructing masters. Great stuff. You deserved every one of those subs and likes.
I am writing this review by just viewing the content for 30 mins. I loved it. I was bit reluctant to start as Dynamic Programming is very difficult and yet very important at the same time. This has given me a boost of confidence as i was able to code the same concept in Java. Thank you so much. And Happy Coding everyone. No matter how difficult it seems, we would go through it Together. :)
Hands down. I am not a very good student of programming however, the way this person teaches is impeccable. I am solving questions side by side and I am getting all the answers right within the first go. Thank you so much for your efforts and you should really teach me everything because I am UNSTOPPABLEEE.
Fibonacci tabulation is amazing; this is how you would intuitively calculate n-th fib number by hand. How come I have never thought about it when writing algorithms? Amazing course, many thanks!
this is a godlike Tutorial. I recommend to everyone watching to pause after the problem is introduced and think of a way to solve it and then watch the explanation. Adds some more depth to this amazing work!
I had the same idea, but as @Taniea said, you still end up computing all possible pairs. You don't even save the lookup time, as the lookup occurs before the 'if' condition.
Honestly, this is the most exciting video on coding I've watched in a long time. I'm only about 10% through, and I feel like I'm already a better coder for following along. I don't know JS, so i'm following in Python, and honestly, I think that adds to the value of the video since I have to actually understand the code that Avin is writing before re-implementing it in Python. Also, I'm getting a taste of JS syntax, which is an essential language. Thanks Alvin and Free Code Camp!
After graduating with a CS degree and working for 2 years, I can finally explain to someone what DP is! Phenomenal and unbelievable course. Can't thank you enough for this high-quality content.
Thank you for this tutorial! I'm still going through it, but I wanted to keep a track of any errata I encounter in this comment. 47:00 - The rightmost leaf is labelled as (0, 0) as opposed to (2, 0) 1:04:05 - The space complexity is stated as O(n + m); however, memoization takes O(n*m) space. So, the overall space complexity is O(n*m).
Bro is using 2 tricks called memorization and tabulation all over the video but there are more tricks to cover those problems such as 1. Optimization Using Space Reduction 2. Recursive With State Compression 3. Greedy Algorithms and more, but it was impressive on how bro using visualize to cover those problems for a nearly newbie to fully understand. Great work out there man. 💬
Before I thought I would never be able to solve problems using dynamic programming , but now I have a lot more confidence. Thank you for this amazing video😁
For the howSum code, if you're having trouble spreading the array (in case you're using something other than JS). Try solving it with booleans, kinda like the canSum problem, and then if it returns true, then just add the num in a global array/ ArrayList/ Vector.
Regarding the grid traveler, in the diagram section before coding the solution you said that 1, 2 and 2,1, 3, 2 and 2, 3 are basically the same with the same possibilities, so for the check key = m, n key in memo shouldn't we also checked for key = n, m key in memo? That would cut the amount of recursive calls but about a half, no?
47:00 last node to the right should be 2,0... still a base case, so no difference overall, but it's best to clarify to prevent people of confusion and frustration...
Alvin, thank you so much for uploading this video. I got into programming as some kind of a hobby. Your video not only taught me two very important principles, but also brought me understanding for terms that my math teacher-25 years ago-was not able to explain. Thank you so much!!! 🤗
Simply a mandatory video for anyone learning dynamic programming. Astonishingly well planned out, with great examples and explanations. If you're looking at the comments to see if you this is worth your time - it will blow your expectations away.
Two hours into the video and I was able to write my own little recursive function without looking at any notes! I never understood it before! The visualization at the beginning of the video was key for me. Thank you for breaking it down so thoroughly.
For the howSum and bestSum problems, the additional product of m in the complexity can be avoided by mutating the array instead of creating a new one and copying it over. Just use combination.push(num) and it will be O(1) since appending an element at the end of an array is O(1). So time complexity can be O(m*n) and O(m) which is even better. Other than that, great video.
Hey, could you explain why the time complexity of canSum with a memo is O(m*n)? I can understand the brute force way is O(n^m) but I'm confused with the improved one.
@@liangyu3771 Think about how many different ways there are to call canSum. With an amount of m, canSum could be called recursively with any number from 1 to m, so there are m different ways. Similarly, for each node from 1 to m, there are n edges to branch from. In total, there exists at most m * n nodes to traverse through. The difference between n^m and m * n is due to the memo object saving us from doing repeated work.
No. I don't want to be a software engineer at Google. Please leave me alone algoexpert I just wanna learn dynamic programming.
resistance is futile, you will be absorbed, prepare for the interview
@@donsurlylyte haha...me neither. I should apply just for grins, to see what it's like.
Literally every video I click!!
Yeah, man. Whats with the grin .. Little too happy..
in fact, this is the most annoying ad ever! This plump woman with a nasty voice will come to me in my nightmares.
It took me a week to finish this tutorial.
This tutorial is just pure gold.
I always found it hard to understand time complexity for recursive solutions. But this video explains it perfectly.
This is probably the best tutorial on dynamic programming. I can't believe you're giving such quality content for free...
Agree
I guess you already know how to reverse a binary tree...
Key is a tree
Agreed.
Same .. I took more than a week
I am 45 mins in, but I had to stop to drop this comment. This is hands down one of the best tutorials I've ever seen.
Alvin is a true teacher. I am blown away by his style. I have taken paid courses on this topic, but this is the first time I am understanding what this is about. I can't wait to finish this tutorial.
I am going to go for all your courses.
bro what's your current status i mean are you working ?
still can't believe how good this course is, like legitimately taught me more on algorithms, recursion, and dp than anything I've ever seen
You mean so?
The first thing I'm gonna do when I get a job is to donate to FCC. I've learned so much from their content on CZcams and tutorials on their website.
What a good guy!🎉
People like you make me believe in humanity
Good luck! 👍
Ikr! I'm going to do the same. It's only fair.
FCC rocks
This guy has the most relaxing voice of any lecturer I've heard.
So true!
I've been coding since 1998 and have watched countless tutorials on countless topics. This guy is definitely one of the best teachers I've ever come across.
my man Alvin! I'm a Senior Developer but it was always a grind to brush up DSA topics when I'm in the job hunt. Your videos helped me quantify it a lot. I just watch your DSA videos in 1.5x half a day before an interview and that is all I need. Very well put both for beginners and for folks like me who need a quick run-through. This is the kind of stuff internet is made for. Appreciate the great work. keep it up!
Did you get it
After getting frustrated from these dynamics programing, after hunting to know the real concepts in books, articles, online paid courses, CZcams videos, finally got this here and that too free. I can't believe this. He teaches like crazy. Thanks a lot.👍
Alvin is amazing. He currently works for google right now
That's because he is crazy
He's crazy - 01:04:10 - OBVIOUS MISTAKE - he forgot to calculate space occupided by THE CACHE. Space is O(n * m), not O(n + m) OMG OMG OMG
Damn this guy was the instructor for app academy. His explanations actually put me on the track to understanding this crazy world of code. So glad he's back on the scene!!!
we meet again! thanks for watching -Alvin
@@CoderbyteDevelopers ooooo you just got a new sub.
Hey join this guys
www.scaler.com/event/coding-interviews-dynamic-programming?rcy=1&rce=f6cd5eeb1984
@B Q is there a video link for his data structures and programming videos?
@@CoderbyteDevelopers completely off-topic question if you don't mind: What microphone are you using?
This is definitely the best course on Dynamic Programming I have ever done. Notice, not the _best free_ course, the _best_ course, period.
a note: go donate on their website, it's tax free (As they are non profit), they get the full amount and you pay no taxes. CZcams charges taxes to both the channel and the donator.
bro what's your current status i mean are you working ?
This is the slickest way I've ever seen not only Dynamic Programming, but also recursion presented. His slides/animations are just perfect for guiding every single step your brain needs to go through along the way, and he handles all kinds of gotchas and keeps you from getting stuck. I'm already going from "holy cow how am I going to even approach these problems" to "ok this is starting to get intuitive with this workflow" just an hour in. Literally better than any professor's teaching style than I remember from my college CS program. The effort put into this video is insane!
I have a feeling this video just covers some of the basics-intermediate problem types, but I bet this will be a great stepping stone to tackling the harder DP problems.
Phenomenal teacher, I’ve got an hour left and even though I’ve fumbled my way through similar problems I feel I understand everything much better. This is now my go to recommended video for recursion and dynamic coding
does he teach backtracking in the video ? Haven't started watching it.
@@shivamdhir640 not specifically but discussed in some questions
This is the first standing ovation I've given to a CZcams video.
I'm here after watching graph algo. I am a data engineer and I always struggled to understand the space and time complexity, this animation is all I ever wanted. This is by far the best video I watched on dynamic programming. Moreover, Alvin has that charm to keep me captivated for long hours without loosing focus. Keep up the great work man!
i think it would've been better if you supported his main channel
@@billcosta can someone please suggest the main channel of the tutor....
His teaching style looks best to me.
Thanks
www.youtube.com/@AlvintheProgrammer@@ankitjaiswal272
Give this to Alvin
I've never seen anyone before who was able to better and more clearly explain dynamic programming. The way you're leading us there step by step and also how the material is presented is outstanding. I'm very impressed Good Sir :-) Thank you very, very much 🙇
I finished it and I feel like my head is burning from excitement and curiosity for practicing. It was amazing.
Thank you so much for this course
Dynamic programming truly is crystal meth
how good are you in DP now?
which pograming language are you uisng for coding?
If you are using java can i ask you some questions?
@@khz2172 I don't think he's that good, the course only teaches the basics and some simple problems. If you want to become good at DP I think you should practice with some DP problems (from codeforces, for example)
all 5 hours?
This guy is going to be invited to my wedding.
Make sure you have a prenuptial aggrement bro.
@@swordofgrayskull1530 Words to live by
Same
and this will be his 5 hour-long toast speech :D
Invite me too, i wanna meet him 😂😂
I'm not one to watch any 5 hour video but this one really hooked me to go all the way.
Explaining hard things in a simple and engaging way is hard and you delivered it perfectly.
Brilliant video! The entire community of learners owes you a coffee for teaching us this excellent approach to solving the infamous dynamic programming problems. Other videos and books do not go into this well-defined mindset and step-by-step strategy that you need to develop, in order to understand and ultimately solve these problems from a *pragmatic* approach (which is what ultimately aces technical interviews). Keep up the great work, Alvin!
Quality content from Quality Teachers,that too for free!!❤️❤️
Hey join this guys
www.scaler.com/event/coding-interviews-dynamic-programming?rcy=1&rce=f6cd5eeb1984
No, Not for Free. You Paid with Attention Dollars, :)
@Harshil Pandey "Attention Dollars" is dollar you pay when you "Pay Attention" 😏😋
Someone tell this to WhiteHatJr ppl
@@neerajkale I can't still fathom that scam is still running
Simply THE best dynamic programming course on youtube, wonderfully explained.
The course made understanding the difficult concepts a breeze.
Loved the progression of problems, even the harder ones felt easy after understanding the basic strategy and the recipe.
Thank you freeCodeCamp and Alvin.
did u spend money making this comment
@@LogansDarling while I'd argue there are probably better, more direct ways to support a creator, what makes it so weird to you? People have been spending cumulative billions of dollars over the past years just for having their message read on stream or purely for support. It's basically a pay-what-you-want scheme.
If you really feel like shaming other people's spending, I suggest you may start with people buying shiny rocks to put on rings with otherwise zero value and ethically questionable production.
@@TomasLKarlik while I'd argue that shaming someone for how they choose to support someone is lame, financially or otherwise, what makes you think that's what I was doing? People have been being confused by the billions of new features YT has put on their platform over the past years just because they're not used to it. It's basically a guess-what-this-symbol-means scheme.
If you really feel like assuming the motives of peoples' questions, I suggest you may start with people sarcastically belittling people to cancel anyone who doesn't follow their exact position with otherwise zero value and ethically questionable means.
jokes aside i understand how that could be misconstrued as an insult but i was genuinely wanting to kno cuz it could have been like idk
- Spending money on a specific comment.
- Spending money on a channel.
- Spending money on YT.
- Spending money outside of the platform and the YTer giving them the badge.
- No money even being spent and me just thinking something is a currency symbol.
- It could be _anything_ considering how stupid I am, so I have no clue.
although if u kno that its for a specific comment then ig u answered me so thx
(I do think that it's stupid, but that's more on YT's part than the commenter's part. Seems like a stupid feature to add on the platform, but that hasn't stopped YT before so oh well. ¯\_(ツ)_/¯)
@@TomasLKarlik could you shed more light on the more direct ways to support a creator ?
first time seeing a GOLDEN -COMMON- comment on youtube
(sorry... I played too much hearthstone recently...)
Learning to code by myself, this course brought me so much.
I didn't know anything about dynamic programming, not much about time and space complexity.
Now I wouldn't say that i master it of course, but with those great explanations and examples I happened to cruise through all these exercises with ease.
I am genuinely shocked to see how easy it is for me now, as those problems just seemed impossible before and their solutions looked like witchcraft.
Thank you so much, this is a wonderful course !
This is THE BEST algorithm course I have ever seen on youtube. Wish there are more videos like this!
It's amazing to realize that grid traveler problem sounds like a completely different problem to fibonacci, but it's solved with the same pattern. Just wow.
@black c yeah, C(m + n, n).
which pograming language are you uisng for coding?
If you are using java can i ask you some questions?
You will find in theory of computation that the problems are divided into sets of similar problems ie we can reduce any problem to any other problem to solve and if we can solve just one problem in that set in an more efficient time complexity then we can solve other problems in that set the same way
Wow. Dynamic programming looked so daunting on the outside. In a matter of 2 days, you changed my mindset about it for good :)
Now it seems easy and doable. Many thanks!
Thanks for the great content.
In gridTraveler problem, base condition could be that if either of rows or columns is 1 , we can return 1
So, if(m == 1 || n == 1) return 1;
And i think we could just check m and n interchangeably :
if ((m + "-" + n) in memory) return memory[m + "-" + n];
if ((n + "-" + m) in memory) return memory[n + "-" + m];
As number of ways to travel a grid for (2,3) will be same as number of ways in case of (3,2)
This is the best dynamic programming content I've ever seen. What I found particularly helpful is being able to understand and view recursive problems as a tree. Because of course trees are recursive data structures. When you have a tree from the outset, as long as you understand general principles of DFS and BFS, a lot of solutions become obvious. What this guy does is show a way to make the implicit, explicit. It's that step that is usually the most difficult because sometimes you're just given a number and asked to solve the problem. Once you understand that problem with that starting value represents a tree of decisions, it allows you to visualize it in such a way that the solution becomes evident. Great job.
This is one of the most clear and succinct explanations on the memoization and tabulation techniques for dynamic programming!
which pograming language are you uisng for coding?
If you are using java can i ask you some questions?
This man literally taught me more dynamic programming than paid university courses
Kis language ka hai, c ya c++ ,ya java
This is the problem with America lol
@@milkmeapollo9048 entire world dude , I aint american but my country has the same problem , universities are the biggest scams ever.
@@user-wl5tv4jl7v it's not a scam but they are definitely over priced. I think of college as my source for what I need to know, and the internet (mainly youtube) as my source of knowing those things. Without college/universities, it's hard to know what you need to know. It would take a lot of asking questions and bothering people who didn't sign up to be questioned... lol
I usually can't symphatize with ppl who say this, but yeah, DP is probably the biggest thing the internet has been able to taught me better than a price-near-the-seven-hundred-thousand-colombian-pesos uni course.
YOu should be given an award as the best tutor on Dynamic Programming concepts in the history!!! You approach is so detailed and step-by-step. You found the best formula on how to teach these complex things. Thank you very much for your job!!!
00:00 Intro to dynamic programming
3:22 Understanding the need for Dynamic programming
10:48 Understanding time complexity and space complexity
22:27 Back to the need for dynamic programming with an example
23:31 Dynamic programming - how it reduces the time complexity
25:56 Implementation of dynamic programming using memoization
38:38 More problem
I can't believe you made this with over 2,000 slides. You're a hero.
What did he use to create those slides ?
Yeah, that coordination is spot-on.
The visualization and break down of these concepts are so well done. Kudos!
This is an amazing and helpful tutorial!
For GridTraveler program, we can solve it analytically. Assume a grid with size m*n , then to go from the top left to the bottom right, the total number of step moving right has to be (n-1), and the total number of step moving bottom has to be (m-1), the overall total number of step has to be n-1+m-1 = m+n-2.
Any particular path is an arrangement of steps of these two types of directions. Therefore, it is equivalent to say that if we have total m-1+n-2=m+n-2, then count the number of ways we can pick m-1. So the analytical solution is (m+n-2)!/[(m-1)!(n-1)!] , where ! means factorial
I watched this in just 2 sittings. The explanations are so clear and well laid out. A lot of repeats of course, but that's kind of a good thing in this case because it helps to get used to the topic. Alvin is an amazing teacher.
Had I searched for "dynamic programming" two days earlier, this video wouldn't even have been uploaded to youtube. The timing couldn't be better!
This course just proves that when you go through each minute detail of a problem in a calm and precise manner, while also hinting at the obvious even, a student is much more likely to pick up on the subject. Judging by all the other comments, slower people like myself are starting to get the concept. 🤣
Fantastic coure, thank you very much for uploading this piece.
I don't think it's about slow or quick, it's just that schools don't teach us how to think. They just cram crap down our throats and expect use to puke up rainbows.
The author did not include in the compute complexity the access of the memoized data. For the fibonacci, the algorithm can be optimized to o(1) instead of o(n).
o(1) for storage.
Thanks for the fabulous course 👏🙏One modification that I think the video needs is that for the grid travel algo with memoization, the space complexity is O(m*n) and not O(m+n) [1:04:15]. The stack of course uses O(m+n) space but the 'memo' object grows to store m * n key/val pairs. So the overall space complexity would be O(m*n).
one of the worst things about learning new DSA concepts is the jump in logic/thinking thats made where it doesn't make sense until you've done a million examples because people don't really explain their thought process and the intuition behind it much.
this has none of those issues. this is probably the best DSA video i think i ever seen. amazing work, thank you. 🎉
This is hands down the best crash course on dynamic programming. After struggling for so many hours on dp, I actually feel that I understand the logic and process for tackling dp problems now. Thank you for this amazing video!
I love the way he teaches and his love for coding can be seen in his face, whenever he smiles after hitting the code. Thanks man
for the tabulated canSum, although changing the outer loop bound to i
In the example of canConstruct 2:24:00 you can use the method `startsWith` since you're just interested in knowing if the target starts with the word, so you don't need to traverse the entire string finding the index! Amazing course btw I really appreciated!
Repent to Jesus Christ “We demolish arguments and every pretension that sets itself up against the knowledge of God, and we take captive every thought to make it obedient to Christ.”
2 Corinthians 10:5 NIV
@@repentandbelieveinJesusChrist3 Annoying-ass bot.
Also, I was thinking, can't you also use a trie to pre-compute data within the word bank, so you can efficiently access it during the recursion?
No book can explain DP this well and believe me I have tried!
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Man, Alvin, I watched your Graph Algorithms course first and I absolutely loved it! I saw people there, recommending this legendary course and I just knew I had to come here! Every single second watching this video was completely worth it!
There is no way I can praise your explanation enough Alvin! There just is not!
After this going through this video, I went from literally have no clue whatsoever about what dynamic programming even means, to completely falling in love with this subject. I would surely indulge myself into this subject, and I believe that this video right here is simply the best entry point for any developer out there who is willing to learn this subject.
Thanks Alvin. I am really very grateful!!
Link
@@ytg6663 czcams.com/video/tWVWeAqZ0WU/video.html
Just thank you, for my job I need to write python code for some automation of processes, but I do not have a computer science degree so I kind of leaned on the fly. I knew there was a way of doing some stuff recursively but never tried because I feared it would take me too much time to understand and implement with my basic knowledge. Just with the firsts 2 examples I already have a pretty good idea of how to do it and I am pretty sure it will also help me in the future.
Good luck!
The best tutorial I have ever found on DP. I watched it 2 years ago and again watching till end today. Amazing content and amazing teacher. :)
This is a great short course with a great teacher!! 😉😉😉😙 The classes I attended about dynamic programming in my university are not even comparable to this. This is much more understandable, well presented and makes you want to keep learning the topic.
This the best and most informative explanation of DP I've seen in 25 years! Great job and I hopefully some day you'll be compensated well for your outstanding teaching ability.
1 hour in and I am absolutely loving the content. Still in awe that this kind of knowledge is made available for free!
Very lovely tutorial. I finally feel confident about solving recursion and DP problems.
I have a observation: At 2:32:27, why is the target.indexOf(word) === 0 not factored in, in the calculation for time complexity. Even though we are comparing against 0, target.indexOf(word) will first search through the word, which is (O(m)) before comparing against 0. This should leave us with an overall time complexity of O(n ^ m * m ^ 2).
You literally explained the course in a simple and legit way!! So, DP can be this easy??? 🏃🏾♀️🏃🏾♀️ me heading to leetcode to solve the hard DP problems!
Did you solve some?
Just read the question and backed off???
@@karanveersingh5535 LMAO
This needs follow-up
Famous last word
After finishing this video in 2 full days, I am able to come up with an approach now, and write solutions. No matter how much efforts I made to learn dp, I was no where close to coming up with a neat approach. With these concepts and some more practice on the DP problems, I can sure be good as a hell pro problem solver in a month.
I've always been afraid of DP because of how counter-intuitive it can be sometimes. I also struggled with memoization and tabulation options. Thanks a ton for this video. Helped me a lot.
Definitely, one of the best courses to start with DP. Just started with the tabulation approach and, decided to attempt it after watching the initial explanation. But decided to follow a different approach as below:
def fibDPTabulation(position):
if position
Yeah, I wondered that too, why he's doing forward tabulation instead of backward one. But for the later problems with strings, it really makes much more sense to think forward, so he just wanted to establish consistent practice.
Great so far. If the first half hour is an indicator of the rest, I already learnt more in that half hour than in the past 10 years... Great job
Might be the best video on not just Dynamic Programming, but also for Recursion that I've ever seen
Alvin has made dynamic programming so much easier and quite fun to understand and code in. This video also strengthened my divide-and-conquer concepts, what a cherry on the top!
Recursion tree explanation, animations, multiple examples and the way he helped to visualize how things actually work are just too good.
My man also took things gradually, step by step and covered a lot without letting us get tired of it
Thanks for this tutorial: with your lectures I improved an algorithm that calculates any of level the Pascal's triangle, it was really satisfying to see the big improvement with a very few lines of code
Definitely one of the best instructors I've ever known. Thank you sir
Alvin I have been studying for months and i have taken my time through this video - single handedly drove home soo many concepts and helped me get a solid understanding and an easy translation into Python code. Thank you!
3:52:52 the space is actually the size of the largest value in the numbers array, (due to growing the array to i + num) which could be way larger than the target value (unless I am misunderstanding and the array becomes sparsely represented for a huge index so not memory hungry)
This is one of the best videos on both recursion and dynamic programming I've ever seen. Thank you for making this available and sharing this knowledge with the programming community.
It is always a treat to find content perfectly paired to one's journey in programming. For me, this content is exactly what I need. Thank you Alvin and thank you FCC for distributing! Unbelievable that this is free.
This is great, i love how it starts from a foundation and builds the muscles you need.
I know the course is 5 hours, but I would have loved if it was even 20 hours just building up and up the core knowledge required to solve dyprog problems.
I already feel better and more clear about recursion half way through.
OMG I LOVE THIS GUY! This is the absolute god of dynamic programming. The CS-version of 3B1B.
Apart from the knowledge served, I also want to appreciate the work done to choose colours for slides. It works so perfect for both day and night mode.
1:04:12 The number of paths of [2,3] is the same as [3,2], so the function can be optimized a little more by sorting the keys: if m
you're right, so that solution give O((m+n)/2)
@John Leal i was looking for this in the comments
memoized base case after this optimization would look like
if (m, n) in memo:
return memo[(m, n)]
elif (n, m) in memo:
return memo[(n, m)]
Finally i found the comment i was looking for thanks.
Exactly. He even mentions this while describing the solution, but didn't implement it.
Was wondering that too, I tried it out... Passing a grid of 500,500, I measured the time it took for it to run... 230ms without and 125ms with the sorting.
The way he explained it can't be better! Many thanks.
For the Fab why not this simple algorithm which is faster:
def Fab(n):
f1 = 0
f2 = ff = 1
i = 1
while (i < n):
ff = f1 + f2
f1 = f2
f2 = ff
i += 1
return ff
print (Fab(62))
Because "i" has to iterate over and over until number "n" is reached, which means that the algorithm is based on how large or not is the "n" number, and when an algorithm depends of "n" numbers/items/elements/etc... the representation of it would be linear O(n), better than quadratic O(n^2) approach, not better than constant O(1).
Hope I solve your question nabil, greetings!
You are a coding instructing master. There are millions of people who code, but only a few coding instructing masters. Great stuff. You deserved every one of those subs and likes.
I am writing this review by just viewing the content for 30 mins. I loved it. I was bit reluctant to start as Dynamic Programming is very difficult and yet very important at the same time. This has given me a boost of confidence as i was able to code the same concept in Java. Thank you so much. And Happy Coding everyone.
No matter how difficult it seems, we would go through it Together. :)
Hands down. I am not a very good student of programming however, the way this person teaches is impeccable. I am solving questions side by side and I am getting all the answers right within the first go. Thank you so much for your efforts and you should really teach me everything because I am UNSTOPPABLEEE.
Fibonacci tabulation is amazing; this is how you would intuitively calculate n-th fib number by hand. How come I have never thought about it when writing algorithms? Amazing course, many thanks!
This is probably THE best DP tutorial on the web! Kudos to FCC, Coderbyte, and Alvin.
this is a godlike Tutorial. I recommend to everyone watching to pause after the problem is introduced and think of a way to solve it and then watch the explanation. Adds some more depth to this amazing work!
Hands down, it is impossible to describe in words the way this man teach the recursion problem in first quarter.
So far the best video I have gone through for DP!!!, Thanks Alvin for taking the time for such quality content 😊😊
In the GridTraveler I would have used (1,x) and (y,1) as base cases, as there's only one way to go down a straight line.
yeah more optimization
Same here
Anyways every unique pair is getting calculated only once.
I had the same idea, but as @Taniea said, you still end up computing all possible pairs.
You don't even save the lookup time, as the lookup occurs before the 'if' condition.
I actually felt bad when this course ended. Felt as if a part of my life's story just rested.
😅😄
What a nice line there👍👍
which pograming language are you uisng for coding?
If you are using java can i ask you some questions?
Honestly, this is the most exciting video on coding I've watched in a long time. I'm only about 10% through, and I feel like I'm already a better coder for following along. I don't know JS, so i'm following in Python, and honestly, I think that adds to the value of the video since I have to actually understand the code that Avin is writing before re-implementing it in Python. Also, I'm getting a taste of JS syntax, which is an essential language. Thanks Alvin and Free Code Camp!
This video is hands down the best explanation of DP. The guy did a fantastic job of making tabulation a breeze to understand.
After graduating with a CS degree and working for 2 years, I can finally explain to someone what DP is!
Phenomenal and unbelievable course. Can't thank you enough for this high-quality content.
R u doing job ?
Hey, this is truly one of the best tutorials I've seen so far and very appreciated. Many thanks for your time!
Thank you for this tutorial! I'm still going through it, but I wanted to keep a track of any errata I encounter in this comment.
47:00 - The rightmost leaf is labelled as (0, 0) as opposed to (2, 0)
1:04:05 - The space complexity is stated as O(n + m); however, memoization takes O(n*m) space. So, the overall space complexity is O(n*m).
Bro is using 2 tricks called memorization and tabulation all over the video but there are more tricks to cover those problems such as
1. Optimization Using Space Reduction
2. Recursive With State Compression
3. Greedy Algorithms
and more, but it was impressive on how bro using visualize to cover those problems for a nearly newbie to fully understand.
Great work out there man. 💬
Before I thought I would never be able to solve problems using dynamic programming , but now I have a lot more confidence. Thank you for this amazing video😁
Hey join this for more stuffs
www.scaler.com/event/coding-interviews-dynamic-programming?rcy=1&rce=f6cd5eeb1984
The best Dynamic Programing course I've had so far, thanks a lot for the best teacher.
which pograming language are you uisng for coding?
If you are using java can i ask you some questions?
For the howSum code, if you're having trouble spreading the array (in case you're using something other than JS). Try solving it with booleans, kinda like the canSum problem, and then if it returns true, then just add the num in a global array/ ArrayList/ Vector.
Do you even need to spread the array? It seems suboptimal.
You should be able to push onto the array in O(1) time in most languages.
Regarding the grid traveler, in the diagram section before coding the solution you said that 1, 2 and 2,1, 3, 2 and 2, 3 are basically the same with the same possibilities, so for the check key = m, n key in memo shouldn't we also checked for key = n, m key in memo? That would cut the amount of recursive calls but about a half, no?
The good teacher explains. The superior teacher demonstrates. The great teacher inspires. You are a great teacher Sir! Thank you!
47:00 last node to the right should be 2,0... still a base case, so no difference overall, but it's best to clarify to prevent people of confusion and frustration...
I cannot believe that this quality of teaching material is for free!! Your are amazing!!
Alvin, thank you so much for uploading this video. I got into programming as some kind of a hobby. Your video not only taught me two very important principles, but also brought me understanding for terms that my math teacher-25 years ago-was not able to explain. Thank you so much!!! 🤗
This is one of the best explanation for Dynamic programming on entire CZcams. I have never seen such an clean and Fantastic explanation. Thanks alot
Congratulations on making such a clear tutorial! I will definitely point my students to this if they need to get up to speed about dynamic programming
Simply a mandatory video for anyone learning dynamic programming. Astonishingly well planned out, with great examples and explanations. If you're looking at the comments to see if you this is worth your time - it will blow your expectations away.
Two hours into the video and I was able to write my own little recursive function without looking at any notes! I never understood it before! The visualization at the beginning of the video was key for me. Thank you for breaking it down so thoroughly.
For the howSum and bestSum problems, the additional product of m in the complexity can be avoided by mutating the array instead of creating a new one and copying it over. Just use combination.push(num) and it will be O(1) since appending an element at the end of an array is O(1). So time complexity can be O(m*n) and O(m) which is even better. Other than that, great video.
Hey, could you explain why the time complexity of canSum with a memo is O(m*n)? I can understand the brute force way is O(n^m) but I'm confused with the improved one.
@@liangyu3771 Think about how many different ways there are to call canSum. With an amount of m, canSum could be called recursively with any number from 1 to m, so there are m different ways. Similarly, for each node from 1 to m, there are n edges to branch from. In total, there exists at most m * n nodes to traverse through. The difference between n^m and m * n is due to the memo object saving us from doing repeated work.
@@ericx3woo THANK YOU SO MUCH Your comment helped me not only to understand this problem but justify one current solution for my University.