subset partition
Source: Serbia 2003
April 28, 2008
inductionconicsellipsevectorcombinatorics proposedcombinatorics
Problem Statement
Let be an even number, and be the set of all arrays of length whose elements are from the set . Prove that can be partitioned into disjoint three-element subsets such that for each three arrays \left(a_i\right)_{i \equal{} 1}^n, \left(b_i\right)_{i \equal{} 1}^n, \left(c_i\right)_{i \equal{} 1}^n which belong to the same subset and for each , the number a_i \plus{} b_i \plus{} c_i is divisible by .