Number of bus routes [Switzerland 2011]
Source:
January 31, 2011
modular arithmeticgeometrygeometric transformationcombinatorics proposedcombinatorics
Problem Statement
Given is a circular bus route with bus stops. The route can be frequented in both directions. The way between two stops is called section and one of the bus stops is called Zürich. A bus shall start at Zürich, pass through all the bus stops at least once and drive along exactly sections before it returns to Zürich in the end. Assuming that the bus can chance directions at each bus stop, how many possible routes are there?EDIT: Sorry, there was a mistake...corrected now, thanks mavropnevma! :oops: