Java代写 | COMP1406 Assignment 5 Binary Search Tree

Java代写Data Structure实现二分搜索树

Assignment 5

Due Wednesday, August 14th at 11:59pm

Submit a single file called to the submission server

Your zip file must contain a directory called comp1406a5 and all of your .java files must be in this directory. Do not include your .class files.

1. Binary Search Tree [50 marks]

Write a class called StudentBST that extends StudentTree (from Tutorial 5). In this new class, you will override the find(int id) method to be more efficient (you can assume the tree is a valid binary search tree based on ID values). You will override the add() to add a student in the proper place so that the resulting tree is a valid binary search tree.

When you override add(), if a student with the given ID is already in the tree, your method should do nothing and simply return this.

When you override find(), if the search fails you should return null. The find(int id) method must be efficient. That is, it must exploit the fact that the tre is a binary search tree. The find(String name) will essentially be the same as the one you mad for Tutorial 5.

You must have a zero argument constructor that creates an empty binary search tree. All testing will rely on this constructor. Your grade will be zero for this problem if you do not have this constructor.

You will also add a new method

public boolean valid()

that checks whether this StudentBST is a valid binary search tree or not.

Note: recall that a binary search tree is a binary tree that also satisfies the binary search tree property. The binary search tree property is as follows:

For every node n in the tree,

  1. all nodes in the left subtree of n have value less than the value of n
  2. all nodes in the right subtree of n have values greater than the value of n

For our problem the value of a node is the ID number of the student.

2. Gold [50 marks]

Complete the Gold class. You will have to complete the findGold() method and the computePerimeter() methods using recursion.

World is a 2-dimensional grid of Locations. Each location might be a wall or not. If it is not a wall it might have gold and it might not. Each location has four sides to it. You are NOT allowed to move through a wall. A location might be at the edge of the world. You are not allowed to move off of the world (you’ll likely throw a null pointer exception).

The findGold() method will return the total amount of gold that you can find in the world that is reachable from the specified starting location.

The computePerimeter() method computes the perimater of the reachable world from the specified loction.

The perimieter is defined as the sum of all sides of each location that is reachable in a world (from some starting location) that has a wall on the other side of it. You can think of this as the total number of walls that you could touch if you were in the world and could walk around starting from the specified start location. In the following example, white cells denote walls. The perimeter is shown for each(if calculated from any starting location that is not a wall (in black)

world world world

Here are three example worlds (the output of the toString()). Here, s denotes the starting location, g denotes gold and # denotes a wall. The border of the world is also shown but that is NOT a wall.

|s  |
| g |
|   |


|s# |
|   |
| # |

The output for the two methods for these three examples should be

example | findGold() | computePerimeter()
  1     |    >0      |        0   
  2     |     0      |        2
  3     |     0      |        6

For this problem, I would suggest that you modify the MyLocation class (do NOT change the two provided constructors) to add state and potentially behaviour as you see fit. Be sure that you do NOT modify the World and Location classes though. We will test your code by simply calling the two methods in the Gold class with different worlds and starting points.

Submission Recap

A complete assignment will consist of a single file that has a single folder/directory called comp1406a5. The comp1406a5 folder will have the following two files included:

All classes must be in the comp1406a5 package. That is, all files must have the package comp1406a5; directive as the first line. Your code will NOT compile if it does not have this and you will receive zero correctness marks if your code does not compile.


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