Julia's coding blog - Practice makes perfect

I like to do some sports marketing and then like to learn one or two tips. I do not know what to pay attention to, I just start to read one article a time.

I spent over one hour to study Stephens's interview, 20 minutes practice video in 2017 US open. I try to learn from the tennis star. The sports marketing and sponsorship, Stephens does very good job to present herself.

I also like to learn and use the techniques for my coding blog, quora.com writing, and github sharing, and algorithm practice.

Here is the article for me to read.

Now it is 12:25 AM. I have to go to work tomorrow. It is not healthy to stay too late.

Hard work

I know that it takes a lot of hard work for me to achieve something.

Hardship and hunger for success

August 9, 2018

Introduction

Hardship and hunger for success is my study topic for next week. I like to read the article called In Tennis, Hardship and a Hunger to Succeed. The article link is here.

Unstoppable book excerpt is here to read. I just copy some notes from the blog:

I have always believed that unforgiving routine and sacrifice are crucial factors in every success, rather than just talent, whatever talent is, and Sharapova absolutely confirms that in describing how people first started noticing her tennis.

It was not my skill that people remarked on. It was my concentration — that I could do it again and again without getting bored.

And also this quote of Masha’s first coach, Yuri Yudkin, whom Sharapova met while living in Sochi.

To be great at anything, you have to be able to endure a tremendous amount of boredom.

My experience

I like to write something about hunger for success. I just could not believe that it is already two months since my last trip to Seattle.

Actionable techniques to get any job offer

August 9, 2018

Introduction

It is 12:04 AM. I tried to search good research topic for me to think about in the day time. I came cross this one by a Facebook product manager. Here is the link. The title is called Actionable techniques to get any job offer.

My notes

Be likable
Interviewers are looking for people who will create value for the company while being fun to work with.

Pitch an idea
Pitching an idea like this is a great way to start an interesting conversation and be a memorable candidate.

Know yourself

Last minute research topic

August 8, 2018

Introduction

It was 11:59 PM and I like to find a research topic for me to have a happy day and go to sleep. The topic is called secret interview technique by a Facebook employee. Here is the link.

I know that most of hard working people share their work on Leetcode discussion panel. I like to set a goal to share my practice as well. I like to track how quick I can learn from the community. Here is my sharing.

Tuesday, August 7, 2018

It is time to change my attitude

August 7, 2018

Introduction

It is time for me to work on my attitude. I like to do some study how to collaborate with people better. I overestimate the online judge's power but underestimate the power of person. I learn to respect the authority through bible teaching starting from year 2001.

I like to find some study material for me to get inspiration how to work with people better. I like to make people life better by saying sorry, thank you, it is my fault.

Study time

I like to read the article about Roger Federal. Here is the link.

Three moments shaped Federer as a player and as a man

A brash, belligerent teen to a 19-time major winner. Three moments shaped Federer as a player and as a man. One such moment he was powerless to control.

Federer didn't slide down a slippery slope as a young, angry talent, and believes his coach Carter's death shocked him to maturity. Carter died in car accident while on safari in 2002.

Second is to split with the coach Peter Lundgren at age 22. Roger no longer needed a mate on tour. Lundgren was a mate of his. He would sit in a car with him, turn on the music, let him scream his head off on the highways of Miami, play silly games, get all that out of his system.

"Suddenly Roger Federer started to become a man. He didn't need that looking after anymore."

Actionable Items

It is such great story about Roger Federer.

I had same issues I guess as Roger did from 19 years old to 22 years old about loud music issue.

I spent hours to listen the music from June to August 2018, for example, I can listen the same song over 10 times in a week, Duo Lipa, I am the one.

I was busy to study lyrics and meaning of song, but that is all I can do. But I could not be educated too much after those hours long music listening.

I have to learn how to deal with frustration, loss, and failure, and learn how to get comfortable with myself.

Usually it is good for me to study those tennis players, after the first round loss, how they handle the loss. Just move on. Do not overreact.

Also I have to push myself more often and get under the stress of work on design of the algorithm. One thing I can do is to push myself to solve one or two algorithms a day.

I notice that Leetcode discuss is a good place for people to share and get inspiration on algorithm and data structure. A lot of people already share their experience and they are very successful in terms of career.

I also like to share more and see if I can help myself as well in the learning process, I will try to put all 40 algorithms I practiced called two weeks drill and share them one by one on Leetcode discuss.

It is Sunday morning 8:00 AM. I had chance to talk to my ex-coach forty minutes about a few algorithms and he also gave me his analysis. He is in the city of Beijing and I am in the city of Vancouver.

It is so surprising to have a coach and then I know what to do next. I like to write down the conversation by the time.

Time line

8:00 - 8:10
I described the algorithm called to define an iterator for list of iterators. He said that he did not really understand the problem, so I explained the problem to him. There are two possibilities, one is all lists are sorted, second one is not sorted. If all lists are sorted, then define a minimum heap. If all lists are not sorted, then put everything in the minimum heap. The time complexity should be nlogm, n is total nodes in all lists, m is number of lists.

He said that if the list is not sorted, it can be sorted using in place, like quick sort as well. ( I like the idea and did not think about it at all. )
你也可以把一个 iterator 排好序，用 inplace, quick sort.

I told him that I studied the algorithm one day before, called Merge k sorted lists in Leetcode.

The coach said that you have to calm down, work on more Leetcode easy level algorithm. You can finish 40 algorithms in one month (July 10 - August 5), one year you can finish 400 algorithms. Overall, if you do not practice enough, you will be nervous, or all kinds of problems.

Julia：我感觉紧张。我照你说的去做，刷了四十道题。二道题都在里面。
Coach：刷题没有刷够。就会出各种问题。就像高考，你没有考好。不是再考一次，应该准备一年，基本功练好。中国人就只能刷题。
Coach：你现在一个月刷了 40 道题，一年就能刷400 道题。你可以写邮件要求第二次，但是只看现场表现。
Julia：刷题感觉累。周六就刷了五道题。
Coach：不能赶速度。有时候我刷题也感觉累。动脑太多。

8:10 - 8:20
我开始讲bad version 这道题。我想用数值，提醒用数组，预处理就用了时间 O(N). 我用了二个变量，好的和坏的version。用二分法，找中间值。如果是坏的，看左边的邻居是好还是坏。
这道题从开始到结束就用了20分钟。我就没有给机会回到第一道题。不停地提问题。

8:20 - 8:30
我开始讲 infix expression to construct binary expression tree. 用堆栈来做。(1+2), 把(1+2推进栈，碰到)，开始出栈。
其实我想拿一部分分数，没有用堆栈。不管如何，用堆栈。postfix 用堆栈。但是infix也是可以用堆栈，你自己多用几个左右括号，就自己搞定规则。

coach：可以转换成 postfix expression.
Julia: 不用转。直接用堆栈。反正用多余的左右() enforce priority. 多余的左右() 便宜。

8:30 - 8:40
Julia: 我开始讲刷题把一个BST转换成链表。我开始把左子树换成链表，连到右子树链表。花了一个小时。通不过。换一种思路，用二个变量，前一个和当前，五分钟写出来。觉得不对，把第一个思路做通。用中序做了，想想后序也有可能做通。
coach: 刷题把几种思路都做了。有时刷了100道，其实就刷了10道。你把多个思路都刷了，下一道就可能有同样的思路。

Julia：我觉得这次刷四十道题，刷出兴趣来了。以前刷题少，因为没有体会到乐趣和好处。还有就是刷题好的多的，就不在朋友圈里。

Julia：我又讲一道难题，一年前刷了，几个月前又研究了，写了十个博客。各种想法。结果还是不会做。这次我就记住一个例子，自己解释如何用这个例子，解释如何除去多余括号。链接在这：去除多余的左右括号。

Julia: 我还在做面试, interviewing.io, 我最近碰到一个Waterloo本科生，做过二次谷歌实习。他解题就比较有策略。把问题弄清楚。

Julia：我沟通问题，一问一答。我有时回答问题。接着说。
coach：这个不好指导。只能靠多刷题。题目见的多了，自然就会轻松应付。

It is better to study leetcode by the tag called design. Here is the link.

Two more links:

//https://www.youtube.com/channel/UCPumyEKs86w-GtWDd2XQYtg
//https://www.youtube.com/channel/UCDHkPnEcrEf3B9-isB4jXIw

Learn dynamic programming

I chose to learn dynamic programming using Leetcode 10: regular expression matching over 10 round of mock interviews.

The interviewee suggested me to work on 10 dynamic programming on elements of programming interview, and then work on easy level dynamic programming on leetcode.com

Summary

I had chance to meet a strong undergraduate student on mock interview. I learned from his performance. We had discussion over one easy, two hard level algorithms. And also we had exchanges of ideas how to work on interview, and how to prepare.

One of statement May be an argument or fact:

Waterloo undergraduate computer science students, all they do are working on algorithm problems and prepare for interview.

References

Feedback from the interviewee

Interviewer feedback

Friday, August 3, 2018

Leetcode 23: Merge k sorted lists

August 3, 2018

Introduction

It is a hard level algorithm called Merge k sorted lists. I could not believe that I had to learn the algorithm again in such a short time. I spent over 30 minutes to study one of Leetcode discussion and wrote first time using SortedDictionary to implement C# minimum heap.

My practice

Here is my C# practice of the algorithm called Merge k sorted lists.

Related algorithm

I spent 30 minutes to rewrite mock interview algorithm called K messed array using minimum heap. It is so excited to learn how to write a minimum heap using C# using less than 20 lines of code.

Here is the algorithm code written for K messed array.

100-hard level algorithms 2018 summer campaign

Here is the hard level algorithm folder. I like to document the learning of the algorithm.

Challenge

Here is the fact:

Julia, you spent 10 rounds of mock interviews from March 2017 to June 2018. You could not come out using SortedDictionary to write a simple minimum heap for K messed sorted array algorithm.

Give a few arguments to defend yourself:
I do not spend time to read SortedDictionary source code.
I do not know how SortedDictionary class is designed, why it is needed.
I do not try to memeorize all APIs from SortedDictionary.
I do not have chance to read the code using SortedDictionary to solve the problem.
I did search why C# does not provide PriorityQueue like Java.
I got so many choices to continue to study and improve. I just move on other problems to solve.

Give a few advice how to break through the problem:

Please provide a possible three solutions you can approach to come out a written solution like using SortedDictionary.

Wednesday, August 1, 2018

Morris traversal review

August 1, 2018

Introduction

It is the most classical traversal using O(1) space called Morris traversal. I had a discussion with a friend starting from 8:30 PM and then we discussed the algorithm more than 20 minutes.

Here is the transcript.

I also like to review one of blogs I studied a few years ago. It is written by a facebook engineer in Chinese. Here is the link.

Quick sort technique study

July 31, 2018

Introduction

It is time for me to review the algorithm using quicksort technique. Here is the gist.

Leetcode 40: combination sum II

Leetcode 47: permutations II

Leetcode 46: permutations

Leetcode 90: subsets II

Leetcode 111: minimum depth of binary tree

July 28, 2018

Introduction

It is an easy tree level algorithm called minimum depth of binary tree. I like to consider two ideas, one is to use breadth first search and then shortest path and then terminate search early. Another one is to use recursive function to do depth first search, to prune the search, if the current depth is bigger than minimum depth found so far, then current path should be terminated.

My practice

Here is my C# code. My first practice failed on one test case. My base case is wrong. I should consider the base case with a node not null, but left child and right child both are null. Null node should not be considered as a base case.

weekend planning - 80 facebook algorithms on Leetcode.com

July 28, 2018

Introduction

It is time for me to make my summer weekend special one. I choose to work on facebook algorithm 80 of them on Leetcode.com.

I will plan to work on a few hours based on the list of algorithms

Here is the list I prepared before.