摘要：
有一棵二叉树，最大深度为D，且所有叶子的深度都相同。所有结点从上到下从左到右编号为1，2，3，...，2^D-1。在结点1处放一个小球，它会往下落。每个内结点上都有一个开关，初始全部关闭，当每次有小球落到一个开关上时，它的状态都会改变。当小球到达一个内结点时，如果该结点上的开关关闭，则往左走，否者往... 阅读全文
摘要：
A very big corporation is developing its corporative network. In the beginning each of the N enterprises of the corporation, numerated from 1 to N, or... 阅读全文
摘要：
X-PlosivesA secret service developed a new kind of explosive that attain its volatile property only when a specific association of products occurs. Ea... 阅读全文