Sudoku solver

January 20, 2018

Introduction

It is another 10:00 PM mocking interview. At the very beginning, I always say that my name is Julia. I am in the city of Vancouver. I have been working on C# last eight years, web programmer. And then the peer told me that he is xxx and then he has been working for yyy last 5 years.

I was so surprised to learn that the mock interview has such great machine learning algorithm. I just got another senior developer with one of top four software companies and then we will spend one hour together to discuss the algorithm.

Code review

The algorithm I had to work on is called Sudoku solver. What I have to do is to write down the problem, constraints, and also explain the depth first search and idea to apply backtracking algorithm.

The peer did ask me how to optimize the function getAvailableChars, there are 27 searches.

Here is the C# code with analysis as well. I start to pay attention to the analysis in mock interview, make sure that I can write very clearly about problem, given constraints, and the problem to solve, the idea to solve the algorithm problem.

I went over the constraint in the matrix first, and the write down Constraint, and then write down the main idea of the algorithm: DFS + backtracking, and go over the first row three elements in depth first search, and then the peer told me that he understood the algorithm and I can write the code.

I continue to write down the time complexity and space complexity. The time complexity is 9⁸¹ at most, but I wrote it wrong 81⁹. The peer asked me and then I corrected it.

The only thing I found in whiteboard testing is line 32, I forgot to add !, it should be if(!isDot).