HDU5956 The Elder(树上斜率DP)

最新推荐文章于 2024-07-28 11:47:02 发布

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最新推荐文章于 2024-07-28 11:47:02 发布 · 2.5k 阅读

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本文介绍了如何使用树DP和斜率优化解决HDU5956题目，通过推导转移方程并利用斜率优化将复杂度从O(N^2)降低到O(N)。作者提供了类似问题链接，并详细说明了在树上进行搜索和状态恢复的方法。

题目：

Once upon a time, in the mystical continent, there is a frog kingdom, ruled by the oldest frog, the Elder. The kingdom consists of N cities, numbered from east to west. The 1-th city, which is located to the east of others, is the capital. Each city, except the capital, links none or several cities to the west, and exactly one city to the east.
There are some significant news happening in some cities every day. The Elder wants to know them as soon as possible. So, that is the job of journalist frogs, who run faster than any other frog. Once some tremendous news happen in a city, the journalist in that city would take the message and run to the capital. Once it reach another city, it can either continue running, or stop at that city and let another journalist to transport. The journalist frogs are too young and simple to run a long distance efficiently. As a result, it takes