最小循环节

Power Strings (POJ-2406) 题面 Given two strings a and b we define ab to be their concatenation. For example, if a = “abc” and b = “def” then ab = “abcdef”. If we think of concatenation as multiplication, exponentiation by a non-negative integer is defined in the normal way: a^0 = "" (the empty string) and a^(n+1) = a*(a^n). 输入 Each test case is a line of input representing s, a string of printable characters. The length of s will be at least 1 and will not exceed 1 million characters. A line containing a period follows the last test case. ...

Period (HDU-1358) 题面 For each prefix of a given string S with N characters (each character has an ASCII code between 97 and 126, inclusive), we want to know whether the prefix is a periodic string. That is, for each i (2 <= i <= N) we want to know the largest K > 1 (if there is one) such that the prefix of S with length i can be written as AK , that is A concatenated K times, for some string A. Of course, we also want to know the period K. ...

Cyclic Nacklace (HDU-3746) 题面 CC always becomes very depressed at the end of this month, he has checked his credit card yesterday, without any surprise, there are only 99.9 yuan left. he is too distressed and thinking about how to tide over the last days. Being inspired by the entrepreneurial spirit of “HDU CakeMan”, he wants to sell some little things to make money. Of course, this is not an easy task. ...

简介 Knuth-Morris-Pratt字符串查找算法，简称为“KMP算法”，常用于在一个文本串S内查找一个模式串T的出现位置。这个算法由Donald Knuth、Vaughan Pratt、James H. Morris三人于1977年联合发表，故取这3人的姓氏命名此算法。时间复杂度O(|S|+|T|)。 ...