OJ Board

I agree. It would be a draw if you add an extra empty square at the end of the row, though.

I'll illustrate the solutions with 4 ones per row and column. They work with any (p+1), with p being a prime number. Here, p=3, in problem 135, p=11. SOLUTION 1) Start building this part of the matrix: 1111000000000 1000111000000 1000000111000 1000000000111 0100 0100 0100 0010 0010 0010 0001 0001 00...