MathDB
PAMO 2017 Shortlst: Sum of maxima of adjacent pairs in permutation

Source: 2017 Pan-African Shortlist - I4

May 5, 2019
combinatoricsInequalitymaximum valueminimum valuepermutations

Problem Statement

Find the maximum and minimum of the expression max(a1,a2)+max(a2,a3),++max(an1,an)+max(an,a1), \max(a_1, a_2) + \max(a_2, a_3), + \dots + \max(a_{n-1}, a_n) + \max(a_n, a_1), where (a1,a2,,an)(a_1, a_2, \dots, a_n) runs over the set of permutations of (1,2,,n)(1, 2, \dots, n).