I have a list of 5 numbers and I need to find combinations that equals to a target number. My resulting coombination looks like this ((x * x) + x) * (x + x). I am trying to think of the most holistic solution that may just return other target number provided that I can use other arithmetic operations like +, -, *, /. This is like Knapsack problem and I know my solution would be much expensive but I just need some guidance or pointing in the right direction.