摘要：
DescriptionThe inversion number of a given number sequence a1, a2, ..., an is the number of pairs (ai, aj) that satisfy i aj.For a given sequence of ... 阅读全文
摘要：
Bobo has a tree,whose vertices are conveniently labeled by 1,2,...,n.Each node has a weightwi. All the weights are distrinct.A set with m nodesv1,v2,.... 阅读全文