CareerCup

I would use... wait. What are the scenarios?

First i would think of what operation will be done in a car parking:
--- add a car in the first empty parking space
--- delete a car from a given index in the parking lot
--- check if there are any empty spaces available


I would use a hasmap to map the parking spot to the car parked on it.
I would use another hashmap to keep track of te empty slots in order.

Car Parking is constant in Space. A Car comes and you part it. It goes and its place is taken by another car. There is no such thing as shuffling or FIFO so the answer should be Array. Design Pattern ??

Hashtable would be better compared to heap. heap gives the max or min in O(1) time, but wat abt cars in the middle of the heap ?

This does not make any sense for me. The heap allows to get the smallest or the biggest element in constant time after the heap is created in linear time... but when a new car comes we have to rearrange the heap it depens from the value... I do not know but to represent parking I thin the best would be just an array of spaces

Inside the park, we can use a hashtable or simply use a linklist, outside the park there might be a buffer, we can use a queue.

I would use a hashmap to map the parking spot to the car parked on it.

I would use a heap to keep track of empty slots as u can define some ordering(distance to be travelled to park or frequency by which a person uses a car etc..) on the empty slots

I will consider the problem as producer/consumer problem.
- producer are the cars waiting to park
- consumer are the cars parking out.
- the shared resource (buffer space) is the size of the parking.

The rest is direct implementation of the problem.

Can't we use a queue of indices queue<row,col>
The following would be the operation
- when car arrives, check is the queue is empty or not?. if not empty allocate the front element to the car and pop the front element
- when car leave the parking space, push it to the back of the queue

Why heap?

I would like to use heap DS. Which has a perfect ordering.

Because, heap's space and time complexities are very efficient. Just browse through the Wiki for Heap datastructure. If you can customize your functions then time complexity can be reduced polynomially.