Function day_counts 

fn day_counts(partials: &[TicketPartial]) -> [usize; 7]

Calculates the occurrences of each weekday within the date range covered by the tickets.

This function determines the minimum and maximum dates from the provided TicketPartial slice and then counts how many times each weekday occurs within that inclusive date range. This is useful for normalizing ticket counts against the number of available days for each weekday.

Arguments

• partials: A slice of TicketPartial items defining the date range.

Returns

An array [usize; 7] where each element represents the number of times a specific weekday (Monday=0, …, Sunday=6) appears in the date range.