Coins on number line
Source: Swiss Math Olympiad 2010 - final round, problem 1
March 16, 2010
combinatorics proposedcombinatoricsinduction.
Problem Statement
Three coins lie on integer points on the number line. A move consists of choosing and moving two coins, the first one unit to the right and the second one unit to the left.
Under which initial conditions is it possible to move all coins to one single point?