> For example, trying to decide what is the best way to pack a truck for deliveries is essentially the knapsack problem and has no solution that we could actual

> For example, trying to decide what is the best way to pack a truck for deliveries is essentially the knapsack problem and has no solution that we could actually implement. NP-Complete problems can't be solved in polynomial time, but they can still be solved algorithmically, and the solution to an instance of a problem is perfectly well-defined.