地址:http://poj.org/problem?id=2778 题目: DNA Sequence Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 15453   Accepted: 5964 Description It's well known that DNA Sequence is a sequence only contains A, C, T and G, and it's very useful to an…

Censored! Time Limit: 5000MS   Memory Limit: 10000K Total Submissions: 6956   Accepted: 1887 Description The alphabet of Freeland consists of exactly N letters. Each sentence of Freeland language (also known as Freish) consists of exactly M letters w…

题目 给n个字母,构成长度为m的串,总共有n^m种.给p个字符串,问n^m种字符串中不包含(不是子串)这p个字符串的个数. 将p个不能包含的字符串建立AC自动机,每个结点用val值来标记以当前节点为后缀的字符串是否包含非法字符串(p个字符串中的任何一个). 状态转移方程:f(i, j)  += f(i-1, k) f(i, j)表示长度为i的字符串,结尾为字符j,方程j和k的关系可以从自动机中失配关系直接获得(j是k的后继结点). 总之感觉是好东西,快存下来 大数模版: #include <cs…

题目大意:DNA序列是有 ATGC 组成的,现在知道一些动物的遗传片段有害的,那么如果给出这些有害的片段,能否求出来所有长度为 N 的基因中有多少是不包含这些有害片段的.   分析:也是断断续续做了一天,做这道题前先做一下 hdu2157 这道题,因为这道题的思路就是从它转变过来的,看明白了这个后,就需要构造一个矩阵,不过因为按照自己的想法构造的矩阵,一直WA,不明白为什么,后来发现是因为在子节点不存在时候查询后缀时候包含子节点的时候不彻底造成的,还是对AC自动机了解的不多.不过通过这题也学会了…

题意: 给出患病的DNA序列,问序列长度为n的,且不包含患病的DNA序列有多少种 解析: 以给出的患病DNA序列建trie树  患病结点要用flag标记 对于长度为n的序列 位置i有四种 情况A  C  T  G, buid的时候是从祖结点0开始的四种选择,如果tri树中存在某种选择,则顺着走下去,因为要防止恰好选择了患病DNA序列 若trie树中不存在某种选择,则指向0 即祖结点,因为这个点中断了患病DNA序列的生成 偷个图:https://blog.csdn.net/morgan_xww/a…

Censored! Time Limit: 5000MS   Memory Limit: 10000K Total Submissions: 9793   Accepted: 2686 Description The alphabet of Freeland consists of exactly N letters. Each sentence of Freeland language (also known as Freish) consists of exactly M letters w…

有了KMP和Trie的基础,就可以学习神奇的AC自动机了.AC自动机其实就是在Trie树上实现KMP,可以完成多模式串的匹配.           AC自动机 其实 就是创建了一个状态的转移图,思想很重要.           推荐的学习链接: http://acm.uestc.edu.cn/bbs/read.php?tid=4294 http://blog.csdn.net/niushuai666/article/details/7002823 http://hi.baidu.com/nial…

有了KMP和Trie的基础,就可以学习神奇的AC自动机了.AC自动机其实就是在Trie树上实现KMP,可以完成多模式串的匹配.           AC自动机 其实 就是创建了一个状态的转移图,思想很重要.           推荐的学习链接: http://acm.uestc.edu.cn/bbs/read.php?tid=4294 http://blog.csdn.net/niushuai666/article/details/7002823 http://hi.baidu.com/nial…

Description Aliens on planet Pandora also write computer programs like us. Their programs only consist of capital letters (‘A’ to ‘Z’) which they learned from the Earth. On planet Pandora, hackers make computer virus, so they also have anti-virus sof…

DNA Sequence Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 9899   Accepted: 3717 Description It's well known that DNA Sequence is a sequence only contains A, C, T and G, and it's very useful to analyze a segment of DNA Sequence,For exa…