Overview

• Assignment link: https://classroom.github.com/a/vSCbJjw1
• Format: Maven project

In this assignment, you’ll implement and test a method that constructs and returns an array containing values that follow a very specific sequence: $(0, -1, 4, -9, 16, \ldots)$. As you can see, the magnitude of each value is the next perfect square in the sequence ($0 = 0^2, 1 = 1^2, 4 = 2^2, 9 = 3^2, 16 = 4^2$, etc.), but the signs alternate between positive and negative.

Implementation

Declaration

In the edu.cnm.deepdive.Generator class, the oscillatingSquares method is declared with the following signature, return type, and modifiers:

public static int[] oscillatingSquares(int length)

The implementation must not change the modifiers, return type, method name, parameter types/number/order, or possible exceptions shown above. For more method declaration details, see the Javadoc documentation.

Specifications

• The returned array must contain exactly length elements.

• The value of the element at index position n must be equal to (-1)ⁿn².

For example,

Generator.oscillatingSquares(5);

would return

{0, -1, 4, -9, 16}

Tips

• You may find it useful to create one or more additional static methods as “helpers”; the problem can be solved without doing so, however.

• Don’t hesitate to declare any constants (static final fields) that you feel might simplify or clarify your code.

• The method to be completed includes a TODO comment to that effect.

Unit tests

These cases will be used to unit test the implementation:

length	Expected return value of Generator.oscillatingSquares(length)
0	{}
1	{0}
5	{0, -1, 4, -9, 16}
7	{0, -1, 4, -9, 16, -25, 36}
10	{0, -1, 4, -9, 16, -25, 36, -49, 64, -81}