鄙人第一次做的一个网上书店，只有前台，漏洞很多，三基本的功能有了，-I first do an online bookstore, only the front desk, porous, with three basic functions,

方格矩阵连通性求解,一个矩阵，随机打开一个方格（open），如果打开的方格使得矩阵上边和下边连通，即为连通了。平均需要随机打开多少个方格能使得矩阵连通？-Given a composite systems comprised of randomly distributed insulating and metallic materials: what fraction of the materials need to be metallic so that the composite syste