# Reference patch — 01-motorbikes-share-a-spot

The answer key for how the reference absorbs this change, and the thing that makes
`budget.json` reproducible. **Never shipped to the candidate.**

1. **Add** `SharedMotorbikeAllocator.java` (in this directory) to `reference/src/`. New file, so
   `measureChange` charges nothing for it.
2. **Change one line** in `reference/src/ParkingLot.java`, in the convenience constructor:

   ```diff
   -        this(new SpotGrid(standardSpots), new FirstFitAllocator(), new FlatHourlyPricing());
   +        this(new SpotGrid(standardSpots), new SharedMotorbikeAllocator(new FirstFitAllocator()), new FlatHourlyPricing());
   ```

Measured: `reference_diff = 2` (1 added, 1 removed, one file touched), so
`diff_budget = max(3, 2 + ceil(2/2)) = 3`.

Both the curveball suite (5 tests) and the base suite (10 tests) are green after the patch —
the change is additive in behaviour, not a replacement.
