Simulate bus boarding with priority and wheelchairs

You are implementing a simplified bus boarding simulator.

Model:

• Person has at least:
  • id (string/int)
  • priority (boolean): if true, they should board before non-priority riders.
  • wheelchair (optional): if present, the person uses a wheelchair.
  • capacityCost (int): how many capacity units they consume when boarding (defaults to 1 for a normal rider; wheelchair riders may have different costs).
• Bus has:
  • totalCapacity (int)
  • maxWheelchairs = 2

Task A — Priority boarding:

• Given a waiting line of people (in arrival order) and a bus with remaining capacity, board as many people as possible.
• Priority riders should be boarded before non-priority riders.
• Preserve relative order within the priority group and within the non-priority group (stable ordering).
• Return (1) the list of boarded riders in the order they boarded and (2) the remaining waiting line.

Task B — Explain tradeoffs:

• Explain why you implemented it that way.
• Provide at least one alternative approach and compare time/space complexity and maintainability.
• Mention what you would change for “real production” (e.g., extensibility, fairness/starvation, configurability).

Task C — Unit tests:

• Write unit tests for Task A (and for Task D below if time). Specify key edge cases.

Task D — Add wheelchair constraints:

• Extend boarding logic with these rules:
  • A bus can carry at most 2 wheelchair riders.
  • Each wheelchair rider consumes capacityCost units (not necessarily 1).
  • Non-wheelchair riders consume 1 unit.
• Continue to respect priority boarding and stable ordering within groups.

You may define your own function signatures (e.g., board(bus, waitingQueue)).