KMP匹配算法

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


------------------------------------------------------我是分割线^_^---------------------------------------------------


首先，我不得不说对这个算法还有很多的迷糊，不过已经会大概的模板的，记住kmppre的数组如何做
出来的就差不多了，就是当失去匹配时归回的匹配位置，路还有很远，哎= =

#include<iostream>

#include<algorithm>

#include<cstring>

#include<cstdio>

#include<cmath>

#include<string>

#include<queue>

#include<vector>

#include<cctype>

#include<set>

#include<map>

#include<sstream>

using namespace std;

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

#define INF 0x3f3f3f3f

#define Int __int64

#define pii pair<int,int>

#define check(x) cout<<"["<<x<<"]"<<endl;

const int MAXN = 1111111;

int num[MAXN];

int kmp_pre[MAXN];

int src[MAXN];

void Kmp_Pre(int num[], int len, int kmp_pre[]) {

    int i = 0, j = 0;

    j = kmp_pre[0] = -1;

    while (i < len) {

        while (j != -1 && num[i] != num[j]) {

            j = kmp_pre[j];

        }

        kmp_pre[++i] = ++j;

    }

}

int Kmp(int num[], int len1, int src[], int len2, int kmp_pre[]) {

    int i = 0, j = 0;

    Kmp_Pre(num, len1, kmp_pre);

    while (i < len2) {

        while (j != -1 && num[j] != src[i]) {

            j = kmp_pre[j];

        }

        i++;

        j++;

        if (j == len1) {

            return i - j + 1;

        }

    }

    return -1;

}

int main() {

    //freopen("input.txt", "r", stdin);

    int T;

    while (scanf("%d", &T) != EOF) {

        while (T--) {

            int n, m;

            scanf("%d %d", &n, &m);

            for (int i = 0; i < n; i++) {

                scanf("%d", &src[i]);

            }

            for (int i = 0; i < m; i++) {

                scanf("%d", &num[i]);

            }

            int ans = Kmp(num, m, src, n, kmp_pre);

            printf("%d ", ans);

        }

    }

    return 0;

}