userluoxuan的专栏

解题思路：题目大意是

解题思路：用线段树求逆序对。只需要

解题思路：线段树，点更新，求

解题思路：用每个字符的下标记录

解题思路：区间更新，区间求和的模板题。AC代码：

DescriptionACM has bought a new crane (crane -- jeřáb) . The crane consists of n segments of various lengths, connected by flexible joints. The end of the i-th segment is joined to the beginning

单点更新，区间求和：

DescriptionThe citizens of Bytetown, AB, could not stand that the candidates in the mayoral election campaign have been placing their electoral posters at all places at their whim. The city coun