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自己选择的路,就算跪着也要走完

01/10
21:17
AC自动机 字符串

HDU 2222 Keywords Search AC自动机

In the modern time, Search engine came into the life of everybody like Google, Baidu, etc. Wiskey also wants to bring this feature to his image retrieval system. Every image have a long description, when users type some keywords to find the image, the system will match the keywords with description of image and show the image which the most keywords be matched. To simplify the problem, giving you a description of image, and some keywords, you should tell me how many keywords will be match.

Input

First line will contain one integer means how many cases will follow by. Each case will contain two integers N means the number of keywords and N keywords follow. (N <= 10000) Each keyword will only contains characters 'a'-'z', and the length will be not longer than 50. The last line is the description, and the length will be not longer than 1000000.

Output

Print how many keywords are contained in the description.

Sample Input

1
5
she
he
say
shr
her
yasherhs

Sample Output

3

Solution

题目大意:先给你n个串,再给你另外一个串,问在这n个串中有多少个在最后一个串中出现过。

AC自动机……第一天学,感觉理解的还不是很透彻……

AC自动机简而言之就是在tire树上跑KMP,能在O((N+M)L)的时间内完成一个串与多个串的匹配。AC自动机中的fail数组的获得和KMP算法中的fail数组基本类似。 ps: 关于时间复杂里的 N M L分别为 N个串,长度为L 和 一个长度为L的串匹配