一个树状数组各种改造姿势的模板。除了常规用法单点查询求前缀和外，支持区间修改单点查询、区间修改区间求和、RMQ、离线平衡树以及多维扩展-Many improved versions of binary indexed tree. Which can be used to do these kinds of work in a 1D array:

Change one point+k and get the prefixsum

Change a range+k and get value of one point

Change a range+k and get the prefixsum

RMQ(Range max/minimum question)

An offline balanced tree

2D extend and 2+D is similar