move_x and move_y define next move of Knight . move_x is for next value of x coordinate move_y is for next value of y coordinate
move_x = [ 2 , 1 , - 1 , - 2 , - 2 , - 1 , 1 , 2 ] NEW_LINE move_y = [ 1 , 2 , 2 , 1 , - 1 , - 2 , - 2 , - 1 ] NEW_LINE