Hash练习题：【HDOJ4821】--String【字符串hash】

最新推荐文章于 2020-07-24 18:04:13 发布

转载最新推荐文章于 2020-07-24 18:04:13 发布 · 796 阅读

文章标签：

#NOI

本文探讨了在给定字符串中计算特定长度的可恢复子串的数量，通过结合多个子串来构建原始字符串，并确保这些子串在位置上各不相同且具有多样性。该文提供了一个实例输入输出，帮助理解如何实现这一计算过程。

来源：http://acm.hdu.edu.cn/showproblem.php?pid=4821

另外有一道简单的可以先做：http://acm.hdu.edu.cn/showproblem.php?pid=1800

String

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1439 Accepted Submission(s): 430

Problem Description

Given a string S and two integers L and M, we consider a substring of S as “recoverable” if and only if
(i) It is of length M*L;
(ii) It can be constructed by concatenating M “diversified” substrings of S, where each of these substrings has length L; two strings are considered as “diversified” if they don’t have the same character for every position.

Two substrings of S are considered as “different” if they are cut from different part of S. For example, string "aa" has 3 different substrings "aa", "a" and "a".

Your task is to calculate the number of different “recoverable” substrings of S.

Input

The input contains multiple test cases, proceeding to the End of File.

The first line of each test case has two space-separated integers M and L.

The second ine of each test case has a string S, which consists of only lowercase letters.

The length of S is not larger than 10^5, and 1 ≤ M * L ≤ the length of S.

Output

For each test case, output the answer in a single line.

Sample Input