Leetcode 18: 4 sum

Dec. 27, 2017

Introduction

It is the cold day in the city of Vancouver, I spent the whole day inside the home for another vacation day. I have a whole week off. I only went out with my friends to take a walk in Burnaby central park, and I booked 3 mock interview 12:00 PM, 8:00 PM, 10:00 PM.

First peer is working on next January Google onsite interview, second peer is working on next January Facebook onsite interview. Third peer is from Shanghai, China, he had Google onsite 4 years ago, and then he prepares to get another one.

I was busy to observe how other programmers work on problem solving. My thinking is that young people are smart, and very good at communication, but lack of challenge in daily work or practice compared to working on Hackerrank contest advanced level algorithm. I want to see those determination and dedication in their problem solving process in the future.

 I went through the Hackerrank contest to work on advanced level algorithm, I understood that it is so hard to make things work, score zero from over 5 hours for a depth first search, but the algorithm cannot meet the time complexity requirement.

Those young peers are trying their luck, they will experience how tough the fight is after their onsite interviews. There are some candidates with a lot of practice and being able to solve the problem in less than 10 minutes.

Here is my records of practice:

Leetcode 4 sum

I had mock interview 8 PM. The peer has experience to work for Microsoft, and then I got advice how to improve my code.

My last practice is on Nov. 14, 2017. I wrote the blog the document the practice. And after that I posted a question on code review website but no one gave me review.

Dec. 27 is my fifth time I worked on the algorithm, I wrote exactly same code of 4th practice. But the peer gave me a few of advice to simplify the code.

The above code can be simplified. First look at the redundant code to manipulate the dictionary.

The first is to reduce four variable to two variables, save i, j instead of arr[i],arr[j], i, j. Secondly line 17 and line 23 are the same, extract them outside the if/else branches.

Here is the code after simplification.

Actionable Items

Look into those four companies, Nitanix, Uber, Qualtrix, Splunk.