Leetcode 17 Phone number combination - practice (II)

April 26, 2016

To master this DFS algorithm, Julia likes to do more practice.  Every time she practices, she finds new issue, new concern. She also knows that to memorize a solution is not a good idea, do not focus on what you remember about the algorithm, even you have some memory about the algorithm and solution. You may have to solve a totally different problem. 

Leetcode 17 phone number combination

Review the blog:
http://juliachencoding.blogspot.ca/2016/01/leetcode-17-letter-combinations-of.html

One more practice - write the code using the same idea, still makes a bug, and learn how to do fast coding, add more explanation variable, and temporary variable.

https://gist.github.com/jianminchen/acbbf5fbd5fefa1a9fb2f7b3664bf4ed

https://gist.github.com/jianminchen/90ac4390929704ce439d0a1f255f4546

Make function more flat, close to left side, more readable - remove if/ else statement in the function, more flat; also, more readable code, less chance to have a bug. 

https://gist.github.com/jianminchen/b866a5c331556ea8f36aecfe123befea

Reading:
https://msdn.microsoft.com/en-us/library/zcbcf4ta.aspx
http://geekswithblogs.net/robp/archive/2008/08/13/speedy-c-part-3-understanding-memory-references-pinned-objects-and.aspx

Question and Answer: 
Julia has some concerns about recursive function, she will find some articles to read:
1. General about stack, recursive function.
2. How to check using C# - recursive argument one copy or its own copy?
3. Play safe, use extra variable to save the value.