CSCI 151 - Data Structures and Object-Oriented Development

Spring 2015

Lab 12: Mazes, part 1: Heaps

For this lab, we will implement a heap for storing maze paths.
Download the provided code.
Create a new Java project, into which the provided code will be placed.
The code includes the following files:
- maze package
  - PathHeap.java: Represents a heap for storing Path objects.
    - This is the only file you will modify.
    - Within the file, modify the following methods:
      - leftOf(), rightOf(), parentOf(): These methods should calculate an appropriate array index, given their argument.
      - put(): Adds a Path to the heap, and then fixes heap property violations.
      - remove(): Removes and returns the shortest-length element of the heap, and then fixes heap property violations.
  - Cell.java: Represents a grid location in a maze.
  - Path.java: Represents a sequence of grid locations in a maze. These are the objects that the heap must organize.
  - PathOrderer.java: Interface for path orderings. Implemented by PathHeap; we will later add PathQueue and PathStack.
  - PathHeapTest.java: Unit tests for PathHeap.
Grading
For a grade of A+, the code must not only work, it must also be demonstrably O(log₂ n) time for each put() and remove().

Number of Unit Tests Passed Grade

4 A

3 B

2 C

1 D