kmp

#include <stdio.h>

int t, line, n, m, ar[1000100], ar2[10010], P[10010];

void prefix_function(){
    int i, k = -1;
    P[0] = k;

    for (i = 1; i < m; i++){
        while (k > -1 && (ar2[k + 1] != ar2[i])) k = P[k];
        if (ar2[i] == ar2[k + 1]) k++;
        P[i] = k;
    }
}

int kmp(){
    int i, k = -1;
    for (i = 0; i < n; i++){
        while (k > -1 && ar2[k + 1] != ar[i]) k = P[k];
        if (ar[i] == ar2[k + 1]) k++;

        if (k == (m - 1)){
            return (i - k + 1);
        }
    }
    return (-1);
}

int main(){
    int i, j;
    scanf("%d", &t);

    for (line = 1; line <= t; line++){
        scanf("%d %d", &n, &m);
        for (i = 0; i < n; i++) scanf("%d", &ar[i]);
        for (i = 0; i < m; i++) scanf("%d", &ar2[i]);
        prefix_function();
        int res = kmp();
        printf("%d\n", res);
    }
    return 0;
}