One-way roads between cities
Source: Bundeswettbewerb Mathematik 1971, round 2 problem 3
June 14, 2006
induction
Problem Statement
Between any two cities of a country there is only one one-way road. Show that there is a city from that every other city can be reached directly or by going over only one intermediate city.
I'm sure it was posted before but couldn't find it.