Trip expense binder

File a pile of expense items into trip reports. Trips can overlap, and receipts often turn up a day or two outside the trip.

Each trip is a string "name START END", with dates YYYY-MM-DD; the trip covers every day from START to END inclusive (START <= END). Each item is a string "DATE CENTS": the date of the expense and its amount in cents, an integer that is negative for a refund. Trip names are unique.

Each item is filed under at most one trip:

1. If its date lies inside one or more trips, it goes to the one that started latest; if several of those started on the same day, to the one listed first in trips.
2. Otherwise, it is a *near miss* for a trip if it is within slack days of it: the item is before START by at most slack days, or after END by at most slack days (slack may be 0). Among the trips it is a near miss for, it goes to the one with the smallest gap in days (a day before START or after END is a gap of 1); if the gaps tie, to the one listed first.
3. Otherwise, it is unassigned.

Dates are real calendar dates, so months, leap years and year ends behave normally.

Input: trips, a list of strings; items, a list of strings; slack, a non-negative integer.

Output: a list of strings "name COUNT TOTAL", one for each trip with at least one item, where COUNT is the number of items filed and TOTAL their sum in cents (it can be zero or negative). Order the trips by START ascending, then by name ascending. If at least one item is unassigned, add a final line "unassigned COUNT TOTAL" in the same format (no trip is called unassigned). If there are no items, return [].