Remember, just the subproblem and recurrence structure (no code). You are a tourist visiting the planet Zondor and, since you are unfamiliar with Zondorian coins, you are burdened by way too many of them. The next time you buy something, you are determined to use as many of your coins as possible, and want to give the vendor exact change so you won’t receive any more coins as change.
For this problem, the Zondorian coins have integer values z1, z2, . . . , zn and you can assume that you have a limitless number of each coin. When you purchase something of value Y , you want to determine the maximum number of coins you can give to purchase the item with exact change (you may return some dummy value, -1, 0, ± [infinity], if it is not possible to exactly match Y ). For example, if (z1,z2,z3) = (3,7,11) and Y = 25, you could get rid of 3 coins (3, 11, 11) or, better, 7 coins (3, 3, 3, 3, 3, 3, 7).
So, the problem here is to perform the two steps to start the process of solving the MaxZondor- Coin problem.