Essential things to remember from today's class (class 16, 18th October)

Why the "which coins to give in change" question really can be a problem
   to solve, even though it isn't with American currency.

Absolutely must understand and be able to recreate the recursive solution.

Be sure you completely understand why it can get so slow.

And be sure you fully understand how the solution to "what is the minimum
   number of coins for this amount?" leads directly to a solution to "which
   coins should I use to attain that minimum?"

Make sure you understand and could recreate for another problem the memoised
   algorithm.