Write a method to modify an array so that each element becomes
the multiplicative product of that element, and the elements
immediately before and after it from the original array before
modification. If there are no elements before or after, don't
include them in the product (a single number is its own
product).
For example, the array int [ ] b = {13, 2, 20, 20, -32, 3};
would become {26, 520, -1280, -1920, -96}.
Do not call any methods built into Java or from any third party
to assist your work. Instead, you should perform all calculations
yourself using basic math operations.