Number Sequence HDU - 1711 （KMP算法理解+模板）

先放一个大佬的链接，ke'y可以说是讲的非常详细了：https://blog.csdn.net/v_july_v/article/details/7041827，感谢大佬分享

这篇对部分匹配值介绍很详细：http://www.doc88.com/p-2929643037053.html

说一下我对kmp的理解吧（不一定正确，前辈多zhi'指教）：

     kmp算法的优越性在于不必将p上的字符跟s上的每个字符都作比较，进而节省时间。

    举个例子：“acbacd”这个字符串匹配到最后一个字符错了、于是我看它前面的几个字符特点很明显我们不用重新从头开始比、而可以从字符“b”开始比、因为“acbac”的前缀“ac”==后缀“ac”、相当于间接的比过。

    nexts[ ]数组就是将部分匹配值向后挪1，第一个补 -1

例题：

Number Sequence

 HDU - 1711    

Given two sequences of numbers : a[1], a[2], ...... , a[N], and b[1], b[2], ...... , b[M] (1 <= M <= 10000, 1 <= N <= 1000000). Your task is to find a number K which make a[K] = b[1], a[K + 1] = b[2], ...... , a[K + M - 1] = b[M]. If there are more than one K exist, output the smallest one. 

Input

The first line of input is a number T which indicate the number of cases. Each case contains three lines. The first line is two numbers N and M (1 <= M <= 10000, 1 <= N <= 1000000). The second line contains N integers which indicate a[1], a[2], ...... , a[N]. The third line contains M integers which indicate b[1], b[2], ...... , b[M]. All integers are in the range of [-1000000, 1000000]. 

Output

For each test case, you should output one line which only contain K described above. If no such K exists, output -1 instead. 

Sample Input

2
13 5
1 2 1 2 3 1 2 3 1 3 2 1 2
1 2 3 1 3
13 5
1 2 1 2 3 1 2 3 1 3 2 1 2
1 2 3 2 1

Sample Output

6
-1

题意：T组数据，s有n个数，p有m个数，问从s中的那个位置开始可以将p匹配上

思路：kmp算法模板题

AC代码：

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