HackerRank: Connected Cell in a Grid (III) - C# solution (III) - using recursive function

April 17, 2016

problem statement:

https://www.hackerrank.com/challenges/connected-cell-in-a-grid

Here is the code studied using DFS function with return value.

https://gist.github.com/jianminchen/bc2c399407a30181ca68292459a3c791

Julia likes to practice using same idea, write her own implementation.

Practice #1: 

https://gist.github.com/jianminchen/fd909c3545e2081cf2dd2b6daea5900f

Time spent:

Copy main function from previous implementation, and write recursive function - it takes less than 15 minutes.

First time write, no bug!

April 18, 2018

Here is another writing over 30 minutes:
Practice #2: 
https://gist.github.com/jianminchen/d434bcc59ebc8eb7c2cbb20c6f48ac06

The practice goal is to see if I can shorten the time to 10 minutes in writing. How good I can write.

But, surprisingly, the practice takes 30 minutes; and I found out the several issues:
1. Timeout - recursive calls, if/ while checking
2. Array.GetLength api

First, time out issue; read a row of '0' or '1', should be if, I put a while. <- it takes more than 10 minutes to find out. I pinpoint recursive call, because I have doubt, not 100% sure.

And then, I tried to avoid the recursive call to itself, and then, (dr, dc), mistakely I put (dr, dr); HackerRank shows wrong answers for 2 test cases.

Make one change a time, and see if I can shorten the time to 10 minutes.

Study Array.getLength()
https://msdn.microsoft.com/en-us/library/system.array.getlength(v=vs.110).aspx

Another version, it takes 14 minutes to write, without a bug:
Practice #3: 
https://gist.github.com/jianminchen/bd155e574b32ebb163455dad02fa76b1

Julia's performance is up and down, from 15 minutes to 30 minutes.
Again, all practices links:
#1
https://gist.github.com/jianminchen/fd909c3545e2081cf2dd2b6daea5900f
#2
https://gist.github.com/jianminchen/d434bcc59ebc8eb7c2cbb20c6f48ac06
#3
https://gist.github.com/jianminchen/bd155e574b32ebb163455dad02fa76b1

Work on speed and accuracy. Practice, more concentrated on writing. More alert on bug code. More knowledge about api, and basic things.

Learn Jagged Array -
http://stackoverflow.com/questions/597720/what-are-the-differences-between-a-multidimensional-array-and-an-array-of-arrays