question: public Object key ( ) { int dr = + 1 ; int dc = + 1 ; int offRL = + 1 ; int offRH = + 2 ; int offCL = + 1 ; int offCH = + 2 ; boolean rFirst = true ; int d = board [ 0 ] [ 0 ] ; if ( board [ 0 ] [ MaxC ] < d ) { dr = + 1 ; dc = - 1 ; offCL = 2 ; offCH = 1 ; d = board [ 0 ] [ MaxC ] ; rFirst = false ; } if ( board [ MaxR ] [ MaxC ] < d ) { dr = - 1 ; dc = - 1 ; offCL = 2 ; offCH = 1 ; offRL = 2 ; offRH = 1 ; d = board [ MaxR ] [ MaxC ] ; rFirst = true ; } if ( board [ MaxR ] [ 0 ] < d ) { dr = - 1 ; dc = + 1 ; offRL = 2 ; offRH = 1 ; d = board [ MaxR ] [ 0 ] ; rFirst = false ; } StringBuilder sb = new StringBuilder ( 10 ) ; if ( rFirst ) { for ( int r = - dr + offRL ; dr * r <= dr + offRH ; r += dr ) { for ( int c = - dc + offCL ; dc * c <= dc + offCH ; c += dc ) { sb . append ( board [ r ] [ c ] ) ; } } } else { for ( int c = - dc + offCL ; dc * c <= dc + offCH ; c += dc ) { for ( int r = - dr + offRL ; dr * r <= dr + offRH ; r += dr ) { sb . append ( board [ r ] [ c ] ) ; } } } return sb . toString ( ) ; }
target:  Return key that satisfies rotational symmetry.  Considering the four corners of the board, select the lowest digit and then read off the remaining eight positions in a fixed order as an integer. Return that value.