HackerRank NCR codesprint - Spiral message - After the contest

Nov. 7, 2016

Problem statement


Previous blog about 15 submissions in the 48 hours contest.


After the contest, Julia downloaded all test cases, input/ output, she played with test cases, after more than 30 minutes, she finally figured out her major issue on the problem solving.

From the first 3 lines of problem statement:
The message originated as a single line of one or more space-separated words, but it was encoded into an  matrix as a clockwise spiral starting in the lower left-hand corner. 

Julia did not pay attention to the start point, lower left-hand corner. All her works are from up left-hand corner instead by a mistake. 

So, there are 4 corners:
up left-hand           up right-hand
lower left-hand      lower right-hand

Work on the sample test case: 

3 5
a##ar
a#aa#
xxwsr

The output of spiral message:
xaa##ar#rswx#aa

She did work on the coding in the contest, her output starting from 'a', not 'x'. In other words, sample test case's spiral message - her understanding and output: 
a##ar#rswxxa#aa


So, in the contest, Julia has to train herself to read problem statement more carefully. 

Ideas:
1. Write down all inputs
2. Make a check list
3. Make her own notes, do some research about the algorithm
For example:
1. a spiral message
2. clockwise
3. starting from lower left-hand corner
4. Not from general case - upper left-hand corner
5. ...


She started to work on the algorithm from 11:00am, Saturday, and then, in the evening, from 11:00pm - 1:00am, she came back to work on the algorithm, she read the problem statement again and again, but she did not notice the starting point - lower left-hand corner. 

Actionable Items:

Do not spend more than 1 hour to write code in the contest; go back to read the problem statement again and again; draw your own diagram - anti-clockwise. 

It is easy algorithm. Julia stumbled on easy algorithm so badly. 

C# code after contest - bug-free, clock-wise starting from lower left-hand corner


Year End review:
Review previous work on array manipulation:

1. Previous work on rotate of array

2. array rotation

3. array rotation (II)

4. array rotation (III)

Don't practice 'til you get it right. Practice 'til you can't get it wrong. #tennis #motivation pic.twitter.com/GNpWdF372B

— Tennis Coaching™️ (@tennisdothow) August 20, 2015