MathDB
2014 Guts #27: Maximum Value of Sum of Minima

Source:

August 26, 2014

Problem Statement

Suppose that (a1,,a20)(a_1,\ldots,a_{20}) and (b1,,b20)(b_1,\ldots,b_{20}) are two sequences of integers such that the sequence (a1,,a20,b1,,b20)(a_1,\ldots,a_{20},b_1,\ldots,b_{20}) contains each of the numbers 1,,401,\ldots,40 exactly once. What is the maximum possible value of the sum i=120j=120min(ai,bj)?\sum_{i=1}^{20}\sum_{j=1}^{20}\min(a_i,b_j)?