MathDB
no of 0's on the table is odd then max odd number on table is perfect square

Source: 2018 Saudi Arabia IMO TST I p2

July 28, 2020
number theorycombinatoricsPerfect Square

Problem Statement

Let nn be an even positive integer. We fill in a number on each cell of a rectangle table of nn columns and multiple rows as following: i. Each row is assigned to some positive integer aa and its cells are filled by 00 or aa (in any order); ii. The sum of all numbers in each row is nn. Note that we cannot add any more row to the table such that the conditions (i) and (ii) still hold. Prove that if the number of 00’s on the table is odd then the maximum odd number on the table is a perfect square.