对于某个m*n的字符串数组，相当于一个m行n列的平面形状的方格。里面S表示起点，W表示障碍，B表示可走（但是不一定可以通），X表示出口。对于起点S，有8个方向可以走，当然前提是在没有障碍的情况之下，其中可以分为单步走（on foot）和跳步走（by jump）两种情况，从起点S开始追寻最短的出口路径count2。-M* n to a string array, which is equivalent to an m line n of the plane out of the box shape. Express the starting point of S inside, W express obstacles, B indicated that they could walk (but not necessarily pass), X express export. For the starting point of S, has 8 direction can go, of course, the premise that there are no obstacles in the circumstances, which can be divided into single-step walk (on foot) and the jump step-by-step walk (by jump) both cases, the starting point S from the beginning to trace the the shortest path export count2.