> For the complete documentation index, see [llms.txt](https://mqjyl2012.gitbook.io/algorithm/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mqjyl2012.gitbook.io/algorithm/data-structure/tree-extension.md).

# 树结构的延申

## :pencil2: 1、字典树（前缀树，基数树）

## :pencil2: 2、线段树（区间树）

## :pencil2: 3、树状数组

#### [第k小整数](https://www.luogu.com.cn/problem/P1138)

#### [数字序列](http://acm.hit.edu.cn/problemset/2275)

求序列中满足 $$A\_i < A\_j > A\_k$$ and $$i < j < k$$  的组数。

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