A country has n cities and one airport in each city Some air

A country has n cities and one airport in each city. Some airports are connected with a direct flight. What is the minimal number of flights needed so that one could reach from every city every other city

(a) without stops
(b) stopping at most once

(c) stopping at most twice?

Solution

the minimal number of flights needed so that one could reach from every city every other city

(a) without stops (n-1)^n
(b) stopping at most once (n/2-1)^n

(c) stopping at most twice (n/3-1)^n