HackerRank - Connected Cell In A Grid (II) - C# solution (II) using Queue

April 17, 2:50 - 3:25

Problem statement


First practice using C#,  solution written by Julia:

C# practice by Julia


Study the code: 1. Use Queue, instead of using recursive calls, using 2 dimension array, excellent code to study:

Study code 

So, Julia did one more practice, and just wrote second implementation using idea in the above blog. 

Write C# code again using idea - 2 dimension array, queue, and also, mark the visited node using '2'. 
C# solution 1

Second Practice

It takes 30 minutes to write and fix bug, log interesting things happening in the practice:

1. First, fix the issue to read a row to a string, and then go over one char a time to get each node for the row.

   use Console.ReadKey()  first <- fatal error

2. use wrong local variable about key

3. Count should be 5 but 11 for one test case, count same thing more than once! - > add extra checking before counting. Or, set node is visited just before adding to the queue. 

Compare to the solution #1, two dimension array uses integer 1 or 0, my copy is using char '1', '0';
And also, the solution #1, every node sets visited true before adding to queue.
And my design, do not set, which causes problem. Same node is added to the queue more than once.

It is better to add unvisited node to the queue once.

Julia, you have to make sure that no bug in the code, it does not matter what idea you use. 

Third practice:

Write in 20 minutes, no bug:

3rd practice using C#


Again, 3 practices:

No. 1 - C# code

No. 2 - C# code

No. 3 - C# code