BZOJ3537 : [Usaco2014 Open]Code Breaking

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BZOJ3537 : [Usaco2014 Open]Code Breaking

考虑容斥,枚举哪些串必然出现,那么贡献为$(-1)^{选中的串数}$. 设$f[i][j]$表示$i$的子树内,$i$点往上是$j$这个串的贡献之和,那么总状态数为$O(n+m)$,用map存储$f$. 将子树的DP值与父亲合并时,按串长分类讨论: 若子树串比较长,那么暴力枚举它的前缀状态转移即可. 若父亲串比较长,那么一个子树状态对父亲状态的贡献编码后对应一个区间. 扫描线处理区间,对于相邻的区间内的所有DP值整体乘上一个数,线段树维护. 最后沿着线段树上有效节点走,即可不重不漏地得到所有新的…

bzoj AC倒序

Search GO 说明:输入题号直接进入相应题目,如需搜索含数字的题目,请在关键词前加单引号 Problem ID Title Source AC Submit Y 1000 A+B Problem 10983 18765 Y 1036 [ZJOI2008]树的统计Count 5293 13132 Y 1588 [HNOI2002]营业额统计 5056 13607 1001 [BeiJing2006]狼抓兔子 4526 18386 Y 2002 [Hnoi2010]Bounce 弹飞绵羊 43…

【Coursera】Security Introduction -Eighth Week(1)

Security Introduction People With Bad Intent 今天,Bob 向 Alice 发送了一条 "Hello,Allice!" 的信息,他们希望这条信息只有他们两个人知道,但是邪恶的 C 出现了,他通过非法的手段窃听了这条信息,当然,在这之后,有一堆无处不在的贪图Alice美色的坏人(看来Alice长的很漂亮..),同样的也想要窃听他们之间的对话,怀着邪恶的目的. Paranoia(偏执狂) Who is out to get you? If…

Coursera:Internet History ,Techornology and Security

WEEK1 War Time Computing and Communication Bletchley Park 布莱彻利庄园:a top-secret code breaking effort by the British government during World War II. 二战时期英国政府为了破译德国的"Enigma"电报加密装置而设立的,聚集了一大批高端的密码学.数学人才的基地.最后在Alan Truing(艾伦图灵)的主导下设计了第一个计算机.(以上中文注释来自笔…

Internet History, Technology, and Security（week1）——History: Dawn of Electronic Computing

前言: 第一次进行课程学习,在反复观看视频和查找字典翻译理解后选出了视频中个人认为较重要的概念,以下并不按照逐句翻译,中文概括大意余下自由发挥,对老师想要告诉我们的历史有一个初步的了解,顺便锻炼以下英文阅读理解能力...... War Time Computing and Communication: High Stakes Research in Computing, and Communication We're going to start at the dawn of electroni…

[BZOJ3449] [Usaco2014 Feb]Secret Code

Description Farmer John has secret message that he wants to hide from his cows; the message is a string of length at least 2 containing only the characters A..Z. To encrypt his message, FJ applies a sequence of "operations" to it, where an opera…

How can I protect derived classes from breaking when I change the internal parts of the base class?

How can I protect derived classes from breaking when I change the internal parts of the base class? A class has two distinct interfaces for two distinct sets of clients: It has a public interface that serves unrelated classes It has a protected inter…