Corrected error in labFour_pTwo - thanks Michael Lwe!

 * @return the number of different ways of generating [dollars]

 *    dollars with the permitted bills

 *

 * @example labFour_pTwo_exchange(8) = 6 corresponding to the

 * @example labFour_pTwo_exchange(8) = 7 corresponding to the

 *   following ways to exchange $8:

 *    1. 8*$1

 *    2. 6*$1+$2

 *    4.      4*$2

 *    5. 3*$1      +$5

 *    6.   $1  +$2 +$5

 *    7. 2*$1+3*$2

 */

int labFour_pTwo_exchange(int dollars);