In a country with n cities, there is a recurrent one -way flight between every pair of cities. Every flight has a constant price in the range $100, $120, $140, $160, $180.
A $N flight ticket gives unlimited access to flights that cost $N, and tickets can be traded for tickets of lower prices.
For example, with a $160 ticket, Brad could take a $160 ticket, trade his ticket for a $120 ticket, then take a $120 flight.
Alice loves flying and wonders how many successive flights she can take with one ticket.
Determine the minimum value of n needed to guarantee, that she can take 4 such flights.
(In reply to
I do not understand by Steve Herman)
Oh, now I see what I was missing. Once you trade down to a lower priced ticket, you can no longer take a higher priced flight.
Also, in order to be an interesting problem, the flights need to be distinct.
In fact, the problem is trivial if a flight from A to B is considered distinct from a flight from B to A. We need to limit the problem so that one can only fly once between any unordered pair of cities.
re: I do not understand
