We have a parking lot with several levels and different entrances. We want to implement a utility that would give new cars coming in parking spots that are available. Let’s say that we have 4 entrances, when 4 cars come in, each entrance will show the incoming car the parking spot that car needs to go to.

Please handle additional requirements if the entrance doesn’t show the spot, instead after a car takes a spot, that spot is taken out from the available spots list. When a car leaves a spot, the spot is put back in the pool.