学步园

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
using namespace std;
const int maxn = 1000010;
const int maxm = 10010;
//Accepted 1711 484MS 4260K 1569 B C++ Achiberx 
int a[maxn], b[maxn];
int n, m;
int next[maxm];

void getNext(){
    next[0] = 0;
    next[1] = 0;
    if(m<3) return;
    int j = 0;
    for(int i = 1; i < m; i++) {
        j = next[i];
        if(b[i]==b[j]) {
            next[i+1] = j+1;
            continue;
        }
        else {
            while(j>0) {
                j = next[j];
                if(b[i]==b[j]) {
                    next[i+1] = j+1;
                    break;
                }
            }
        }
    }
}

int match() {
    int j = 0;
    for(int i =0; i < n; i++) {
        while(j && a[i]!=b[j])  {
            j = next[j];
        }
        if(a[i]==b[j]) j++;
        if(j==m) {
            return i-m+2;
        }
    }
    return 0;
}

int main()
{
    int T;
    scanf("%d", &T);
    for(int v = 0; v < T; v++) {
        scanf("%d%d", &n, &m);
        for(int i = 0; i < n; i++) {
            scanf("%d", &a[i]);
        }
        for(int j = 0; j < m; j++) {
            scanf("%d", &b[j]);
        }
        getNext();
        int res = match();
        if(res) {
            printf("%d\n", res);
        }
        else{
            printf("-1\n");
        }
    }
    return 0;
}
/***********************
5
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
***********************/