That ex-Google coding interviewer looked impressed! 😎

He coded the KZfaq algorithm to where more of his videos would pop up in your recommended.

interviewer: does that make sense? him: yeeehaa me: wtf jus happened

(Me who knows nothing about coding): hmm yes yes that looks good

I have no idea what is going on, but I still watched the whole thing

Ok. William is being humble here. Pretty sure if this wasn't an interview he would have completed all the problems in 10 mins.

I have no clue why I’m watching this and why I can’t stop as if I’m absorbing information, even though I’m fucking clueless as to what’s happening

Bruh I feel like a useless human watching this

*"The left property, the right property"* Me: Ahhh, yes its Real Estate

"Am I allowed to Google the solutions?"

This coding interview is so much more practical than regular interviews. Like where do you see yourself in 5 years

"Alright that was like a introduction question" ...... Me: "oh"

And hes a high school student, dang. I can't imagine understanding this stuff in high school.

> Solves leetcode medium > holy shit I'm so smart > goes on this channel > gives up, cries

I have heard about only one tree in my life ; that is Christmas Tree 🎄

“They’re speaking the language of the gods.”

*interview starts for Google * Interviewer: alright let’s get started Me an intellectual: can I use Microsoft Word instead of Google Docs? Interviewer: Get out

Me: *furiously typing* Interviewer: what’s going on? I’m not seeing anything on the Google Doc? Me: *on stackoverflow*

i don't even know what he's doing but i like it

So much fun to see. Still in my first year of studying programming, but it's so fascinating to see him think. Very organized way of thinking and obviously very smart too. Hoping I'll be as fluent with it as him in a few years!

11:56 William: "Does it make sense so far" Clement: "Yes" Me: No. I haven't understood anything.

Hey guys this is so legit I tested w Google interview and failed but the way this video is presented feels exactly how I felt during my interview. Good luck to you if you are planning to interview =)

interviewer: "so now let's move on to something completely different" ... "so let's go back to that binary tree..."

Interviewer: *speaks coding language* Him: *explains coding* Me: yes that makes sense now

Bruh im done, im currently in my second semester for cybersecurity and after seeing this im out

A more eloquent solution for Prompt#2 For each node, add the sum of (original full tree) depth and re-iterate down to zero adding those sums also. e.g. Node#8: its original depth is 3, therefore we know it can be used in up to 3 (sub) trees, each time decreasing in depth. So the total from this node is 3+2+1+0 = 6. The same for Node#9. Node#5 would be 2+1+0 = 3. Add for all nodes and you get 26

KZfaq finding yet another way to make me feel like an idiot

After I watched your interview with Clement, I was so impressed. Your ability to solve this complex problem was very inspiring. You had me subscribed from day 1. Continue to code!

as a high school student ??? Me: OK, shredding my university degree right now.

I'm happy for you, William! I wish you all the best :)

11:57 "Does that make sense so far" "Yup" What you don't see is him quietly going on StackOverflow wondering what the hell he just said

This must be how aliens feels like when they hear our language

I thought I was doing well because I could solve the first part... then they kept adding more and more complexity and I couldn't keep up lmao. I have to re-watch the second half of this video, great job.

He is the chosen one to take down Google

Just watched your Mock interview with Clèment. Great job! I'm very impressed. I started coding for fun. Subbed! Looking forward to your future videos!

Wow inspiring, more video like this please for learning purposes. Thank you! 🙏🏻

Just imagine Clement wrote the problems in text with all the inputs...William would solve all of them like in 10min xD

24:19 Clement smiles when tmw makes progress 🙂

wow Bro . William's voice is so soothing . I can listen to his voice at night and fall asleep . I'm not implying that it is boring , instead it is very relaxing and it gives me tingles (like ASMR) .

Great job!!!! I see a bright bright future ahead of you.

I’m watching this while eating even tho I don’t understand nothing but deep in side hoping I can understand what’s goin on 😂😂

William is definitely being humble and acting like in a real interview (slow down and communicate). Great to watch. Thanks for sharing. I actually came up with BFS in mind first and wonder am I missing anything here if using BFS (for the first two prompts)?

Inspirational AF. Both of them hella good at what they do

You came up with the optimal solutions so quick!

And here i am 24 years old jobless getting rejected in all interviews

*I feel Like I got Smarter and big-brainier just by watching this guy ace this interview!*

Idk anything about coding but this video made me want to learn how to code! I been trying to find a hobby but this is fascinating and fantastic job!

Great Job William continue!

The colab we never knew we needed

Finally joining William Lin Fan Club, I hope tmw spirit will give me strength

I am sitting here at 4 in the morning and this came across my feed and I felt I had to watch the entire thing. I have been in IT since I was 14 and I will say I had no idea what the hell was going on the entire time lol. Took coding in high school but I knew in a few days it wasn't for me. Props to you man.

"just high school student" - funniest shit i've ever heard. Common high school student doesn't have almost 3k CF rating

For the 3rd problem, since you're only asked to return the sum of distances to the target node, I don't think you need another dfs. In the first dfs you updated the target node with the info you need. So after dfs1, ans = p.second - (target->sz) + (p.first - target->sz).

Clement is everywhere!

I swear, I had also learned of everything in what was said here from an Algorithms book but I don't know it as thoroughly as him. I enjoyed this!

im drunk rn but i will pay ALL my attention to this video, normally id for sure not watch this video bc of my pride but i LOVE this type of content bc i actually understand it. THANK YOU WILLIAM

he was hired at 30:10, jittery with voice change, lip bite, hair adjustment and turns of camera ... now that is nerd for love.

i really thought this was an *interview* oh well this just passed through my feed lol

That's a hard question good job I am keeping watching your videos are so helpful improving my skills in understanding problems.

Thanks, this was quite instructive!

That “and 5” really was his time to shine

Imagine being qualified for Google after High School. Nice work, I will follow your channel and see your progress, it's really interesting.

I'm coming up in my senior year of college for software and I feel like I could of came up with these solutions but not nearly as fast. With a whiteboard and 3-5 hours it would be possible, but this guys quick with his thought process

The first question can be seen easily as a sequence. Each node in the rth row has depth (r-1) and there are 2^(r-1) such nodes. So it's just the sum of (r-1)*2^(r-1) where r goes from 1 to n, where n is number of rows. Correct me if I'm wrong.

Practice and passion makes someone good at something? Woah, I would've never guessed.

william seems to struggle with english more than the problems itself lol

crazy how freaking brilliant some people are

I'm actually a little jealous... I wish I had your passion at that age. Super impressive either way, you're an inspiration!

{0:16} Everyone's Gangsta (top right) until they see *Great Great Grandmaster* preparing for coding interview

A much simpler solution for the second problem would be to just change one line of code from the first problem. ans += dep Becomes ans += dep * (dep+1) /2 which is the summation of all number 1 to dep. The logic behind it is that the node at depth 3 will be part of 3 subtrees. And the corresponding depth of that node for those subtrees will be 1, 2, 3. Similar for nodes at depth 1 and 2.

For Prompt 2, an easier approach would be to find the depths of each individual node and just add their sums of AP up

this guy nailed it easily .. he's young, sharp, still flexible . I wish parents was more caring about their children learning good stuff in their free time instead of wasting time on social networks and wasting time on other stuff .. this guy is amazing . I wish my kid one day will be even x10 sharper ! XD

I do work at Google (as or writing this), but these are my personal thoughts. First of all I want to say great job Clement and William. I have really enjoyed your videos and want to thank you guys for the great content. William, you are definitely impressive and have a very good chance of acing your Google Interviews if you choose to give them. One issue in these interviews is the subconscious bias - Clement knows how good William is so even though he tries to be fair and unbiased he is more likely to give William the benefit of the doubt than an average interviewee would get. For instance the solution for the 3rd problem has some issues - they are pretty basic ones and something that are trivial to catch if you're coding in an IDE (can you spot them?). Still that's something that I (and I guess the average Google interviewer) would bring up after the candidate has written code. Won't impact my hiring decision though.

_MEANWHILE MY TEACHER - TAKE INPUT AND PRINT THE EVEN NO._

Keep up the good work clement..could you please make a video on commanly used approaches or ways to solve competitive programs with william

I am happy that i could solve the first problem without trouble

For the 3rd question, even adding the parent node is helpful for using DFS/BFS to solve the problem, but your creative thinking for this question is so cool and the coding for the last question is so amazing. If the interviewee ask to figure out all sumDist for all node, then this solution only need O(N). But the way to add parent node will need O(N^2).

I'm 21 and pretty ok at programming, I'm amazed how fast this dude's brain works (talking about the rest of his kickstart videos cuz this one was pretty straightforward except the 3rd problem cuz it was genius of his to design that formula so quick). I wish I didn't go to college and instead I coded day and night to reach his level at that age lol

"Does it make sense?" No, it doesn't but still gonna watch it

for last problem - if you make tree non-directional (by adding parent pointer to each node) you can treat any node as a root for whole tree and apply solution of the second problem

Im not the only one mesmerized by his pen flipping, right?

Very entertaining William. I watched the whole thing, couldn't understand the other dude tho. I guess you should take the AP CS test for me now thanks!!!!!

Dang bro you killed that problem. Highly impressive

Congrats William! You crushed it at IOI!

I had no idea what was going on...but i found it interesting and watched the whole thing

and here i am, happy because I just moved a div to the center :)

Nice Video!!

Good job young man!

Man he got an IOI silver medal, this has to be pure lightwork for him lol

the beginning looks like a movie intro:)

I could think of the first solution in about 5 seconds and I'm a happy person not even gonna watch the rest for a next few weeks unless I'm good enough to be able to do the second one too.

I wish you would make videos themed on how you got good. Timeline, skills acquired, projects from first to recent, how long do you practice daily, what have you studied, what do you suggest for people to get good or to your level?

Thanks for the great coding interview. I tried to write my own solutions before I continued watching your solutions. And I just attached my codes here. Problem 1: Besides the ordinary dfs, I also wrote a one-line solution that works. int sumDepths(Node* root) { return root ? 2 + sumDepths(root->left) + sumDepths(root->right) : -1; } Problem 2: Actually, you can modify your previous dfs solution to get the answer. Suppose the node in the entire tree has depth 3, then node in the subtrees (including the entire tree) has depths 3, 2, 1, 0, sum to 6. That is true to each node. Thus, int ans = 0; void dfs(Node* root, int d) { ans += d * (d + 1) / 2; // instead of d if (root->left) dfs(root->left, d + 1); if (root->right) dfs(root->right, d + 1); } Problem 3: I wrote a one-pass solution, but it took me thirty minutes... vector find(TreeNode* root, TreeNode* target) { // 0: found target or not(0/1) // 1: number of nodes // 2: sum of dists // 3: dist to target from nodes above / for node below, we don't care if (!root) return {0, 0, 0, 0}; vector l = find(root->left, target), r = find(root->right, target); // sum the distances we have so far int sd(l[2] + r[2]), da(0); if (!l[0] && !r[0]) { // haven't found target // add up extra dists to current node // which equal to the sum of nodes below sd += l[1] + r[1]; } else if (l[0]) { // found target on left branch // update the dist from curr node to target da = l[3] + 1; // add up extra dists of all nodes on right branch to target // plus the dist of curr node to target sd += (level + 1) * r[1] + level; } else { // found target on right branch // update the dist from curr node to target da = r[3] + 1; // add up extra dists of all nodes on left branch to target // plus the dist of curr node to target sd += (level + 1) * l[1] + level; } return {root == target || l[0] || r[0], l[1] + r[1] + 1, sd, da}; } int solve(TreeNode* root, TreeNode* target) { return find(root, target)[2]; }

And I'm just sitting here: "Yea, I've got a big tree at home too!" I got lost so fast... :/

you're a super smart dude... big things are in your future

U're really a monster algorithms and coding ... niceee

When he says, "hmmm, k so... k so I think..." that's equivalent to about 4 days of thinking time for me

easy peasy for William lol

Bro I love ur content

People don’t feel bad some are just gifted in certain stuff, you are gifted in different ways, everyone has it’s gift.