/* Write a function
 *
 * void ReverseWordOrder(string& phrase);
 *
 * Which takes in a string of words (i.e. just words and spaces, no punctuation) and reverses
 * the order of the words in that string.  Your function should run in time O(n), where n is
 * the length of the string, and must use O(1) storage space.  This means that your function
 * can't be recursive (stack frames count as storage space), and you can't use STL containers,
 * dynamic arrays, linked lists, etc. unless you can guarantee that they use at most a constant
 * amount of space.  You can use the STL algorithms if you'd like, but be sure that they don't
 * violate the O(n) time or O(1) space requirements.
 */