（kmp）hdu 1711-Number Sequence

Given two sequences of numbers : a11, a22, ...... , aNN, and b11, b22, ...... , bMM (1 <= M <= 10000, 1 <= N <= 1000000). Your task is to find a number K which make aKK = b11, aK+1K+1 = b22, ...... , aK+M−1K+M−1 = bMM. If there are more than one K exist, output the smallest one. 

InputThe 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 a11, a22, ...... , aNN. The third line contains M integers which indicate b11, b22, ...... , bMM. All integers are in the range of −1000000,1000000−1000000,1000000. 
OutputFor 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

#include <iostream>
//#include<bits/stdc++.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <math.h>
using namespace std;
typedef long long LL;
typedef unsigned long long ull;
const int MAX=1e6+5;
int t,n,m;
int a[MAX],b[10005],f[MAX];
int main()
{
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d",&n,&m);
        int i,j;
        for(i=1;i<=n;i++)
            scanf("%d",&a[i]);
        for(i=1;i<=m;i++)
            scanf("%d",&b[i]);
        f[0]=f[1]=0;
        for(i=2,j=0;i<=m;i++)
        {
            while(j&&b[j+1]!=b[i])
            {
                j=f[j];
            }
            if(b[j+1]==b[i])
                j++;
            f[i]=j;
        }
        for(i=1,j=0;i<=n;i++)
        {
            while(j>0&&a[i]!=b[j+1])
                j=f[j];
            if(a[i]==b[j+1])
            {
                j++;
            }

            if(j>=m)
            {
                break;
            }
        }
        if(i<=n)
            printf("%d
",i-m+1);
        else
            printf("-1
");

    }
}