Dive log limits

Check a dive shop's logbook against its no-decompression limit table and list the dives that went over.

table is a list of [maxDepth, limit] rows sorted by increasing maxDepth, both in whole units (metres and minutes). The base limit for a dive at depth d comes from the first row with maxDepth >= d: the table is never interpolated and never rounded down, a dive at 19 m uses the row for 21 m. A dive deeper than the last row is too deep, whatever its time.

dives lists the logbook entries as [diver, start, depth, minutes], in no particular order: the diver's name, the start time in minutes since the shop opened, the maximum depth, and the dive's total time. A diver's dives never overlap and never start at the same minute.

Divers who dive again soon carry leftover nitrogen. For each dive that is not a diver's first, look at that diver's previous dive (by start time) and compute the surface interval start - (previousStart + previousMinutes):

• under 60: deduct half of the previous dive's minutes, rounded up, from the base limit;
• 60 to 179: deduct a quarter of the previous dive's minutes, rounded up;
• 180 or more: no deduction.

The adjusted limit is the base limit minus the deduction, but never below 0. Only the immediately previous dive matters, and it counts even if it was itself over its limit or too deep. A dive is over when minutes is greater than its adjusted limit; being exactly at the limit is fine.

Input: table and dives.

Output: a list of strings for the dives that broke a limit, ordered by start (ties by diver name in ordinary string order): "<diver>@<start>: too deep", or "<diver>@<start>: over by <n>" where n is minutes minus the adjusted limit. Return an empty list if every dive is fine.