1297. Palindrome Time limit: 1.0 secondMemory limit: 64 MB The “U.S. Robots” HQ has just received a rather alarming anonymous letter. It states that the agent from the competing «Robots Unlimited» has infiltrated into “U.S. Robotics”. «U.S. Robots» s…

    [题目链接] http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=12406 [题意] 求最长回文子串. [思路] 将字符串反向拼接在后,中间用一个没有出现的字符隔开,则问题转化为求新字符串两个特定后缀的lcp,枚举对称点i,对称数为奇的情况对应求lcp(i,n-i),对称数为偶的情况对应求lcp(i,n-i-1). 如图所示: 两个后缀的lcp可以用Sparse Table算法(倍增)在O(nlogn)时间内求解. […

http://acm.timus.ru/problem.aspx?space=1&num=1297 (题目链接) 题意 求最长回文子串 Solution 后缀数组论文题 穷举每一位,然后计算以这个字符为中心的最长回文子串.注意这里要分两种情况,一是回文子串的长度为奇数,二是长度为偶数.两种情况都可以转化为 求一个后缀和一个反过来写的后缀的最长公共前缀.具体的做法是:将整个字符串反过来写在原字符串后面,中间用一个特殊的字符隔开.这样就把问题变为了求这个新的字符串的某两个后缀的最长公共前缀.如图:…

1297. Palindrome Time limit: 1.0 secondMemory limit: 64 MB The “U.S. Robots” HQ has just received a rather alarming anonymous letter. It states that the agent from the competing «Robots Unlimited» has infiltrated into “U.S. Robotics”. «U.S. Robots» s…

http://acm.timus.ru/problem.aspx?space=1&num=1297 https://vjudge.net/problem/URAL-1297 给定一个字符串,求最长回文子串. 论文题,摘一下论文的图片,保证一下就看懂了. (由于我摘不下来图片所以用了https://www.cnblogs.com/lidaxin/p/5002878.html的图片,代码也是参考的他) emm要是还没看懂的话稍微解释一下吧. 也就是说,实际上我们是把反串接到正串后面,然后后缀数组高度…

题意:求一个字符串的最长回文子串 n<=1000 思路:这是一道论文题 需要注意的细节: 1.奇偶分类 2.中间的分割符与最后的附加字母都是最小值,但两者不能相同,否则height可能会出现问题 答案即为min(height[rank[x]+1]...height[rank[y]]) ..,..]of longint; x,y,sa,rank,height,a,wc,wd:..]of longint; ch:ansistring; n,m,i,k,max,tmp,t,j:longint; fun…

POJ   3974 Description Andy the smart computer science student was attending an algorithms class when the professor asked the students a simple question, "Can you propose an efficient algorithm to find the length of the largest palindrome in a string…

题目链接:https://vjudge.net/problem/URAL-1297 1297. Palindrome Time limit: 1.0 secondMemory limit: 64 MB The “U.S. Robots” HQ has just received a rather alarming anonymous letter. It states that the agent from the competing «Robots Unlimited» has infiltr…

A positive integer is called a palindrome if its representation in the decimal system is the same when read from left to right and from right to left. For a given positive integer K of not more than 1000000 digits, write the value of the smallest pal…

Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters. This is case sensitive, for example "Aa" is not considered a palindrome here. Note: Assume the leng…