Time Limit: 10 Seconds      Memory Limit: 65536 KB Dr. X is a biologist, who likes rabbits very much and can do everything for them. 2012 is coming, and Dr. X wants to take some rabbits to Noah's Ark, or there are no rabbits any more. A rabbit's gene…

题目链接 Problem Description Dr. X is a biologist, who likes rabbits very much and can do everything for them. 2012 is coming, and Dr. X wants to take some rabbits to Noah's Ark, or there are no rabbits any more. A rabbit's genes can be expressed as a st…

Wireless Password Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 5640    Accepted Submission(s): 1785 Problem Description Liyuan lives in a old apartment. One day, he suddenly found that there…

题目链接 BZOJ1559 题解 考虑到这是一个包含子串的问题,而且子串非常少,我们考虑\(AC\)自动机上的状压\(dp\) 设\(f[i][j][s]\)表示长度为\(i\)的串,匹配到了\(AC\)自动机\(j\)号节点,且已匹配集合为\(s\)的方案数 直接在\(AC\)自动机上转移即可 但是为了防止使用\(last\)指针之类的,计算匹配的串,我们先将原串的集合去重和去包含关系 方案怎么办? 考虑到\(ans \le 42\),一定是刚好若干个原串以最长前后缀相同的方式相接 因为如果不…

题意:目标串n( <= 10)个,病毒串m( < 1000)个,问包含所有目标串无病毒串的最小长度 思路:貌似是个简单的状压DP + AC自动机,但是发现dp[1 << n][5e4]根本开不出那么多空间,似乎GG.但是我们仔细想一下就能发现,既然要包含所有目标串的最小长度,那必然这个串就是只有目标串叠加组成的,只是在叠加的过程中我们不能混入病毒串.所以其实Trie树上有用的点最多就10个,我们只要处理出所有目标串之间"最小有效转化"就行了,那么空间为dp[1…

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 5400    Accepted Submission(s): 1704 Problem Description Liyuan lives in a old apartment. One day, he suddenly found that there was a wireless ne…

http://acm.hdu.edu.cn/showproblem.php?pid=4057 题意:给出n个子串,串只包含‘A’,'C','G','T'四种字符,你现在需要构造出一个长度为l的串,如果这个串里面包含了某个子串,那么答案就会+val[i](如果这个串被使用过了,就不会再有贡献了),要使得构造出来的串的答案最大,问是多少. 思路:只能想到是AC自动机的题目,然后乱搞出一个错误的方法,没想到是这样的操作. n只有10,因此才1024,开一个dp[l][sz][st]的数组,l代表当前的…

题目链接 Problem Description As we know, Rikka is poor at math. Yuta is worrying about this situation, so he gives Rikka some math tasks to practice. There is one of them: Yuta has n 01 strings si, and he wants to know the number of 01 antisymmetric stri…

给你m个字符串,让你构造一个字符串,包含所有的m个子串,问有多少种构造方法.如果答案不超过42,则按字典序输出所有可行解. 由于m很小,所以可以考虑状压. 首先对全部m个子串构造出AC自动机,每个节点有一个附加属性val[u]代表结点u包含的子串集合. 设dp[l][S][u]为长度为l,包含子串集合为S,当前在结点u时,接下来能构造出的合法字符串总数,则dp[l][S][u]=∑dp[l+1][S|val[v]][v],v=go[u][i],0<=i<26; 两遍dfs,一遍dp,一遍输出答…

模板来自notonlysuccess. 模式串只有10个,并且重复出现的分值不累加,因此很容易想到状态压缩. 将模式串加入AC自动机,最多有10*100个状态. dp[i][j][k]:串长为i,在Trie图上的状态为j,已经包含的模式串为k(二进制表示,第x位为1代表已经包含第x个串). dp[i][j][k]为true或false代表该状态是否可达. 沿着Trie图中的边走进行DP,时间复杂度O( 100*1000*1024 ); 最后枚举一下串长为L的所有可达状态,最大值即为结果. PS.…