hdu 1711 Number Sequence KMP

                                                             Number Sequence

 

                                                    Time Limit:5000MS    Memory Limit:32768KB    64bit IO Format:%I64d & %I64u

Description

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  

 

【一道没有不论什么杂质的纯KMP】

 

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int N = 1000010;
const int M = 10010;
int nxt[M];
int P[N], T[M];
int n,m;
void getnext(){
    int j, k;
    j = 0; k = -1; nxt[0] = -1;
    while(j<m){
        if (k==-1 || T[j]==T[k]){
            nxt[++j] = ++k;
        }
        else{
            k = nxt[k];
        }
    }
}
int kmp(){
    getnext();
    int j, k;
    j = 0; k = 0;
    while(k<m && j<n){
        if (k==-1 || T[k]==P[j]){
            ++k;++j;
	    if(k==m) return j-m+1;
        }
        else{
            k = nxt[k];
        }
    }    
    return -1;
}

int main()
{
    int t;
    scanf("%d", &t);
    while(t--){
        scanf("%d%d",&n,&m);
        for(int i=0;i<n;i++) scanf("%d",&P[i]);
        for(int i=0;i<m;i++) scanf("%d",&T[i]);
        printf("%d\n", kmp());
    }

    return 0;
}