Good board filled with 0s and 1s
Source: Kazakhstan international contest 2006, Problem 3
January 22, 2006
combinatorics proposedcombinatorics
Problem Statement
Let be two integers. We call a board filled with 0's or 1's good if
1) not all the numbers on the board are 0 or 1;
2) the sum of all the numbers in sub-boards is the same;
3) the sum of all the numbers in sub-boards is the same.
Find all such that there exists a good board.