描述了关于线段树的一些原理及基本操作，后面引用两个例题详细介绍了离散化，扫描线，以及二维线段树-Describes the segment tree some of the principles and basic operation, followed by reference to the two examples described in detail the discretization, scan lines, as well as two-dimensional segment tr

线段树示例，完成Mayor s posters-To segment tree example, the completion of the Mayor' s posters