https://hackernoon.com/practical-data-structures-for-frontend-applications-when-to-use-segment-trees-9c7cdb7c2819
The Segment Tree works like other tree data structures. It creates query paths that limit the amount of processing required to return data. Each intermediate node of the tree represents a segment of the data set. The root node contains the sum of all numbers in the tree. Its children contain the sums of all the numbers in their respective ranges, and so on down the tree to leaf nodes
TODO
莫队算法 (Mo's Algorithm)
https://zhuanlan.zhihu.com/p/25017840
A Segment Tree is a data structure that can be used to perform range queries and range updates. It is a height-balanced binary tree, usually built on top of an Array. Segment Trees can be used to solve Range Min/Max & Sum Queries and Range Update Queries in O(log n) time.
TODO
莫队算法 (Mo's Algorithm)
https://zhuanlan.zhihu.com/p/25017840
