Problem 3.1: Write a function which takes an integer n, allocates space for a string of n characters, and returns a pointer to that space. [Solution]

Problem 3.2: Write a function which allocates an array of n integers, where n is a parameter to the function. [Solution]

Problem 3.3: Write a function int **create_2d_array(int x, int y) which allocates a two-dimensional array of size x by y and returns a pointer to it. [Solution]