A warehouse uses a shelving system where each shelf occupies a contiguous range of slot positions [start, end) (the end position is exclusive -- the shelf covers slots start, start+1, ..., end-1). The shelves are stored in a list in a fixed order and their ranges do not overlap. Together they cover a sequence of integer slot positions; the slots are ordered first by the shelf they belong to (matching the list order), and within each shelf by ascending slot number.

A picker is assigned a job identified by a zero-based index idx into this ordered sequence of all covered slots. The picker needs to remove that specific slot from the system. Removing a slot may: ...