question: public boolean isAdjacent ( Cell c ) { if ( equals ( c ) ) return false ; if ( col == c . col ) { return ( Math . abs ( row - c . row ) == 1 ) ; } if ( row == c . row ) { return ( Math . abs ( col - c . col ) == 1 ) ; } return false ; }
target:  Determines if this is adjacent to the given cell either horizontally or vertically. Doesn't check for invalid c because we don't know the  full size of the board within Cell.