Assignment

Brief

public static int[] MergeAndReorder(int[] a, int[] b) { }

Arrays a and b are both already sorted in ascending order. Your task is to merge all elements in a and b, sorted in descending order. You may not use any native sorting functionality of C#, such as SortedList or .OrderBy().

Your variables may only be primitives (and obviously an integer array for the result).

You will be assessed according to the efficiency, correctness and clarity of your algorithm.

Please also explain in a separate paragraph in English how your algorithm works.

Algorithm

The two source arrays are already sorted in a ascending order, which means that the largest values (the ones that we want to at the front of our resulting array) is at the end of the source arrays.

So working from the back we compare the values and decide which value to transfer to our resulting array.

A: [1, 3, 5, 7, 9]
B: [2, 4, 6, 8, 10]

In JavaScript we can simply remove(pop) the elements from the source arrays and then add them to the result(push).

In C# the arrays are defined and resizing arrays is very costly so using position variables we traverse the array in reverse order(--) and the result array in ascending order(++).

Finally at the end the result array is filled up by the remaining items in either source arrays.

Resulting array:

[10,9,8,7,6,5,4,3,2,1]

Testing

The testing method takes a title and two source arrays then compares it by running it against the native concatenation and sort of an array and the MergeAndReorder function.

Files

• index.html: Algorithm test written in Javascript.
• Program.cs: Algorithm test written in C#.