使用数组类型C赋值给表达式

I have this assignment for my Algorithms class to write a system for a car dealership that allows them to search through their inventory so that the complexity of the search is not O(n). To solve this I chose to use a binary search tree that points to the different models of cars and then using three different BSTs to allow for searches of each model for price, mileage and year. I have this assignment for my Algorithms class