Write a mergesort function which makes three recursive calls of length n/3 on an array of size n, and then merges three sorted arrays into one. void mergesort (int a, int * aux, int length): You need a special case for arrays of length 2. The programming language is C or C++; test your code before submission using the gcc or g++ compiler. Please remove all dead code; try to program as clearly as possible, since I try to read it. Your function for this should be less than fifty lines of code long. Do not copy code from another student on from the web; this is an easy project, and must be all your own work