Nasty 5x5 table
Source: 2019 CSMO Grade 11 P4
July 30, 2019
combinatoricsBashingmatrix
Problem Statement
Let be a matrix with each entry be or . Let be the -th entry of (i,j=1,2,\hdots,5). Consider all the ordered sequence in the rows, columns and diagonals of in the following:
\begin{align*}
&(x_{i,1}, x_{i,2},\hdots,x_{i,5}),\ (x_{i,5},x_{i,4},\hdots,x_{i,1}),\ (i=1,2,\hdots,5) \\
&(x_{1,j}, x_{2,j},\hdots,x_{5,j}),\ (x_{5,j},x_{4,j},\hdots,x_{1,j}),\ (j=1,2,\hdots,5) \\
&(x_{1,1},x_{2,2},\hdots,x_{5,5}),\ (x_{5,5},x_{4,4},\hdots,x_{1,1}) \\
&(x_{1,5},x_{2,4},\hdots,x_{5,1}),\ (x_{5,1},x_{4,2},\hdots,x_{1,5})
\end{align*}
Suppose that all of the sequences are different. Find all the possible values of the sum of all entries in .