Violet's notes on the Stack Overflow Challenge #16
A greedy algorithm, starting by taking as much of the biggest coins and then filling the remainder with smaller, doesn't work. Counter example: [[5,4,3,1],[1,1,100,100],7]
If you use the 5, you are stuck with 5 + 1 + 1, but if you take the 4, you get 4 + 3.