Walmart Labs Challenge, due 07/07/2017

Installation instructions

1. Download the Java 1.8 JDK (I am using the macOS version) from Oracle's Java 8 Downloads Page:

   • Run java -version in your bash terminal to ensure you have the proper version of Java accessible in your command line:

   java version "1.8.0_131"
   Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
   Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

2. Download Gradle, a Java package manager, using Homebrew:

   • brew update && brew install gradle
   • Run gradle -v in your bash terminal to ensure you have the proper version of Gradle accessible in your command line:

   ------------------------------------------------------------
   Gradle 4.0
   ------------------------------------------------------------
   
   Build time:   2017-06-14 15:11:08 UTC
   Revision:     316546a5fcb4e2dfe1d6aa0b73a4e09e8cecb5a5
   
   Groovy:       2.4.11
   Ant:          Apache Ant(TM) version 1.9.6 compiled on June 29 2015
   JVM:          1.8.0_131 (Oracle Corporation 25.131-b11)
   OS:           Mac OS X 10.12.5 x86_64

3. Clone the repository:

   • git clone https://github.com/yingw787/walmart_challenge_07_07_2017 /path/to/directory

4. Install dependencies:

   • Build the project using the script in the Scripts.

Dependencies

• Listed in build.gradle.

Scripts

• Build the project:

  • ./gradlew build

• Execute the executable:

  • ./gradlew run

• Run tests:

  • ./gradlew test

Assumptions

• The problem describes a "performance venue", which is assumed to be some collection of seats.
• Assume that there is one instance of a "performance venue" in any given process.
• The problem describes "best available seats", which is taken to assume that seats have different desirability.
  • Assume that for the BasicPerformanceVenue, the desirability of a seat is linearly proportional to the row the seat is in (do not consider columns, levels, etc.)
• Assume that end-user inputs are all sanitized, and all user information (such as email addresses) are validated.
• Assume that one ticket matches one seat.
• Assume that you can only reserve a seat after it has been held.
  • This is because seatHoldId is only accessible in reserveSeats() after SeatHold object has been returned from findAndHoldSeats().
• Assume that no assumption is made about the seat's position within the performance venue, and that value is attached to each seat by itself.
• Assume that if not all the seats could be allocated in findAndHoldSeats(), then do not reserve any seats (instead of reserving all BasicSeats possible).
• Assume that for BasicPerformanceVenue, the venue will never change size after being constructed (if in the future it does, instantiate a new BasicPerformanceVenue and copy data over).
• Assume that freeing and re-allocating the seats will be outside the immediate scope of this challenge as it is not specified in the interface, and will not be tested (although the classes built do support such behavior).

Design Considerations

• All classes should implement an interface.

• Use private variables when possible, and only expose with public methods, to avoid pollution.

• Avoid chaining exceptions to avoid code duplication.

• When updating state, update on a copy of the state first and then write back, so that you have a way of rolling back if an exception occurs.

• Keep the amount of dependencies to an absolute minimum, and import only those you need (do not do anything like import java.util.*)

• I considered having a barebones BasicSeat class, and having the BasicPerformanceVenue be a pair of stacks. That way, allocating a BasicSeat would be popping a BasicSeat off of an "available" stack of BasicSeats and pushing onto a stack of "held" or "reserved" BasicSeats. However, using a Stack would limit access to BasicSeats not recently pushed or popped, and access may be required for those BasicSeats.