Manacher

最长回文(HDU-3068) 题面 给出一个只由小写英文字符a,b,c…y,z组成的字符串S,求S中最长回文串的长度. 回文就是正反读都是一样的字符串,如aba, abba等 ...

Girls’ research(HDU-3294) 题面 One day, sailormoon girls are so delighted that they intend to research about palindromic strings. Operation contains two steps: First step: girls will write a long string (only contains lower case) on the paper. For example, “abcde”, but ‘a’ inside is not the real ‘a’, that means if we define the ‘b’ is the real ‘a’, then we can infer that ‘c’ is the real ‘b’, ’d’ is the real ‘c’ ……, ‘a’ is the real ‘z’. According to this, string “abcde” changes to “bcdef”. Second step: girls will find out the longest palindromic string in the given string, the length of palindromic string must be equal or more than 2. ...

吉哥系列故事-完美队形II(HDU-4513) 题面 吉哥又想出了一个新的完美队形游戏！ 假设有n个人按顺序站在他的面前，他们的身高分别是h[1], h[2] … h[n]，吉哥希望从中挑出一些人，让这些人形成一个新的队形，新的队形若满足以下三点要求，则就是新的完美队形： ...

Palindrome(POJ-3974) 题面 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?” A string is said to be a palindrome if it reads the same both forwards and backwards, for example “madam” is a palindrome while “acm” is not. The students recognized that this is a classical problem but couldn’t come up with a solution better than iterating over all substrings and checking whether they are palindrome or not, obviously this algorithm is not efficient at all, after a while Andy raised his hand and said “Okay, I’ve a better algorithm” and before he starts to explain his idea he stopped for a moment and then said “Well, I’ve an even better algorithm!”. ...

Best Reward(HDU-3613) 题面 After an uphill battle, General Li won a great victory. Now the head of state decide to reward him with honor and treasures for his great exploit. One of these treasures is a necklace made up of 26 different kinds of gemstones, and the length of the necklace is n. (That is to say: n gemstones are stringed together to constitute this necklace, and each of these gemstones belongs to only one of the 26 kinds.) ...

简介 Manacher’s Algorithm是用来查找一个字符串的最长回文子串的线性方法，由一个叫Manacher的人在1975年发明的。中文谐音“马拉车”算法。时间复杂度O(|S|)。 ...