Sign on Fence CodeForces - 484E 可持久化线段树区间合并+二分

隔阂0323

于 2019-08-03 20:08:00 发布

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分类专栏：线段树

本文链接：https://blog.youkuaiyun.com/why932346109/article/details/98368512

本文介绍了一种使用可持久化线段树解决区间合并问题的方法，具体应用是在一个包含多个面板的篱笆上放置最大高度的标志。题目要求在给定宽度的标志能在指定区间内放置，并且高度最大化。通过将高度转化为线段树中的1和0，然后寻找最长连续1的子区间来确定可行的最大高度。通过二分搜索和可持久化线段树实现高效求解。

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Bizon the Champion has recently finished painting his wood fence. The fence consists of a sequence of n panels of 1 meter width and of arbitrary height. The i-th panel's height is hi meters. The adjacent planks follow without a gap between them.

After Bizon painted the fence he decided to put a "for sale" sign on it. The sign will be drawn on a rectangular piece of paper and placed on the fence so that the sides of the sign are parallel to the fence panels and are also aligned with the edges of some panels. Bizon the Champion introduced the following constraints for the sign position:

The width of the sign should be exactly w meters.
The sign must fit into the segment of the fence from the l-th to the r-th panels, inclusive (also, it can't exceed the fence's bound in vertical direction).

The sign will be really pretty, S