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Videos uploaded by user “Yusen Zhang”
Find kth largest element - 15min Coding Challenge
 
12:02
Thank you for all your support! We have reached over 100 subscribers. I know this is nothing in the world of Youtubers but it means a lot to me. I look forward to the next milestone of 1,000 subscribers!
Views: 2655 Yusen Zhang
(Lincoln Memorial) 15 min Java Coding Challenge - Count and Say
 
16:51
For those of you who are new to my channel, here is the procedure of my coding challenge: 1, Open up a random number generator and a timer. 2, I would get a random number generated by Google. 3, A question of easy level would be chosen based off of the random number. For now, my 15 min challenges only do easy questions because medium and hard questions would usually take more than 15 mins to finish. Today's video was filmed at the staircases of the Lincoln Memorial.
Views: 797 Yusen Zhang
Integer To English Words - 30 min coding challenge
 
46:45
Sadly I went over time but luckily I was able to nail this tricky question! Which question would you like me to do next?
Views: 316 Yusen Zhang
Meeting Rooms II 30 Mins Coding Challenge
 
28:08
Coding Style - Accepted Jitsu!!!
Views: 280 Yusen Zhang
(Washington Monument) 15 min Java Coding Challenge - Validate IP address (FAILED)
 
18:06
I went straight to the Washington Monument right after work today. It took me a while to find a good spot to film the video cuz I wanted to have a good shot of the Monument. I got unlucky and picked a long question today so I was not able to finish it. Sorry! I will talk about my solution in the next video. At least the function can compile with no errors lol. My legs were numbing after I finished the video so it took me about 10 mins to get back on my feet, literally. I thought I was gonna freeze there for the rest of the day. Solution to the question: https://discuss.leetcode.com/topic/71444/java-simple-solution
Views: 210 Yusen Zhang
(Romanian Food Festival) 15 min Java Coding Challenge - Array Intersection
 
15:22
Today's coding challenge took place at the Romanian Food Festival in Maryland. I had a hard time concentrating because of the loud music in the background lol. But that's the point of the coding challenges: we want an unsettling environment to simulate the intensity during a coding interview. The festival was not as Romanian as I thought it would be, I think since nobody was dancing to the traditional Romanian music, they just gave up and played mainstream American music. Anyways, it was a fun event overall. I also had an interesting chat with a senior couple and exchange contacts.
Views: 110 Yusen Zhang
Intersection Of Two Arrays II - 15 min coding challenge
 
14:25
After 5 months of summer break, I'm back!
Views: 438 Yusen Zhang
30 min Coding Challenge(Failed) - First Missing Positive
 
01:02:55
Yes....I failed again....I guess I'm not skilled enough for hard questions yet. I need more practice with medium and easy questions.
Views: 410 Yusen Zhang
(Union Station) 15 min Java Coding Challenge - Log Messages
 
12:59
First, my thoughts go out to the victims at the Las Vegas shooting. Today's challenge took place at the Union Station in Washington DC. I had a hard time concentrating because there were a lot of people walking around and checking out what I was doing. They probably thought I was hacking the WIFI at the train station lol. It was a good mental training though. Luckily I finished the challenge in 12 mins.
Views: 95 Yusen Zhang
Word Ladder - 30min Coding Challenge
 
31:32
Haha I just realized at the end I didn't even use the unvisited hashset......NOOB!
Views: 1633 Yusen Zhang
15 min Java Coding Challenge - Search Insert Position
 
18:34
Today was not so challenging because I did it at home. Sorry guys I got lazy lol. I definitely was not as nervous and sweating as much as I would be in public. I failed today because I forgot to offset the high variable (high = mid + 1) during switching mid. Stupid mistake!!!
Views: 90 Yusen Zhang
15 min Java Coding Challenge - Power of Three(FAILED)
 
19:31
For those of you who are new to my channel, here is the procedure of my coding challenge: 1, Open up a random number generator and a timer. 2, I would get a random number generated by Google. 3, A question of easy level would be chosen based off of the random number. For now, my 15 min challenges only do easy questions because medium and hard questions would usually take more than 15 mins to finish. The solution to today's challenge is as followed: public boolean isPowerOfThree(int n) { // 1162261467 is 3^19, 3^20 is bigger than int return ( n lt 0 && 1162261467%n==0); }
Views: 109 Yusen Zhang
15 mins Java Coding Challenge - Longest continuous increasing subsequence (FAILED)
 
18:53
For those of you who are new to my channel, here is the procedure of my coding challenge: 1, Open up a random number generator and a timer. 2, I would get a random number generated by Google. 3, A question of easy level would be chosen based off of the random number. For now, my 15 min challenges only do easy questions because medium and hard questions would usually take more than 15 mins to finish.
Views: 106 Yusen Zhang
15 min Java Coding Challenge - Lowest Common Ancestor
 
11:44
I almost got it wrong: TreeNode left = lowestCommonAncestor(root.left, p, q); TreeNode right = lowestCommonAncestor(root.right, p, q);
Views: 286 Yusen Zhang
Maximum Vacation Days - 30min Coding Challenge
 
30:26
Music: Chopsticks Brothers - Little Apple 徐梦圆 - China-P
Views: 344 Yusen Zhang
15 min Java Coding Challenge - Excel Sheet Column Number
 
13:16
Lesson learned from this challenge is that: We always convert XXX to integer from left to right, which is kinda counter-intuitive to how you would do in your head.
Views: 183 Yusen Zhang
30 min Java Coding Challenge - Insert Delete GetRandom()
 
39:14
class RandomizedSet { Map[Integer, Integer] table; List[Integer] randomList; /** Initialize your data structure here. */ public RandomizedSet() { this.table = new HashMap[Integer, Integer](); this.randomList = new ArrayList[Integer](); } /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */ public boolean insert(int val) { if(table.containsKey(val)) return false; table.put(val, randomList.size()); randomList.add(val); return true; } /** Removes a value from the set. Returns true if the set contained the specified element. */ public boolean remove(int val) { if(!table.containsKey(val)) return false; int pos = table.get(val); if(pos != randomList.size() - 1) { int last = randomList.get(randomList.size() - 1); table.put(last, pos); randomList.set(pos, last); } randomList.remove(randomList.size() - 1); table.remove(val); return true; } /** Get a random element from the set. */ public int getRandom() { int len = randomList.size(); if(len == 0) return 0; Random rand = new Random(); int n = rand.nextInt(len); return randomList.get(n); } }
Views: 135 Yusen Zhang
Word Break - 30min Java Coding Challenge
 
17:49
Sorry about the interruption at the end. Someone was knocking so I had to get to the door!
Views: 751 Yusen Zhang
15 min Java Coding Challenge - Closest BST value (FAILED)
 
23:14
Yesterday I went to sleep at around 2 in the morning and woke up at 6:30 so I was definitely not in good shape for this lol. But I still wanted to make this video and see how my performance would be with drowsiness. Yup, it turned out to be bad. Moral of the story: get a good sleep before your interview. That's more important than anything else.
Views: 84 Yusen Zhang
15 min Java Coding Challenge - Contains Duplicate II
 
17:36
For those of you who are new to my channel, here is the procedure of my coding challenge: 1, Open up a random number generator and a timer. 2, I would get a random number generated by Google. 3, A question of easy level would be chosen based off of the random number. For now, my 15 min challenges only do easy questions because medium and hard questions would usually take more than 15 mins to finish.
Views: 142 Yusen Zhang
30 min Coding Challenge(failed) - First K Pairs with Smallest Sum
 
55:47
Explanation for the question(Chinese): https://www.youtube.com/watch?v=IoNLpJ787RI
Views: 293 Yusen Zhang

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