MathDB
1,2,...,20 on the blackboard

Source: Indonesia IMO 2010 TST, Stage 1, Test 4, Problem 1

November 12, 2009
invariantcombinatorics proposedcombinatorics

Problem Statement

The integers 1,2,…,20 1,2,\dots,20 are written on the blackboard. Consider the following operation as one step: choose two integers a a and b b such that a\minus{}b \ge 2 and replace them with a\minus{}1 and b\plus{}1. Please, determine the maximum number of steps that can be done. Yudi Satria, Jakarta
Back to ProblemsView on AoPS