HDU 1711 Number Sequence——kmp

模板题

#include <cstdio>
using namespace std;
const int maxn = 1e6 + 10;
int t, n, m, T[maxn], P[maxn], fail[maxn];
void Getfail() {
    fail[0] = 0;
    for (int i = 1, j = 0; i < m; i++) {
        while (j && P[i] != P[j]) j = fail[j - 1];
        if (P[i] == P[j]) j++;
        fail[i] = j;
    }
}
int Search() {
    Getfail();
    for (int i = 0, j = 0; i < n; i++) {
        while (j && T[i] != P[j]) j = fail[j - 1];
        if (T[i] == P[j]) j++;
        if (j == m) return i - j + 2;
    }
    return -1;
}
int main() {
    scanf("%d", &t);
    for (int kase = 1; kase <= t; kase++) {
        scanf("%d %d", &n, &m);
        for (int i = 0; i < n; i++) scanf("%d", &T[i]);
        for (int i = 0; i < m; i++) scanf("%d", &P[i]);
        printf("%d\n", Search());
    }
    return 0;
}