HDU1711 KMP

Number Sequence

Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 14563 Accepted Submission(s): 6392

Problem 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
5
2 1 2 3 1 2 3 1 3 2 1 2
2 3 1 3
5
2 1 2 3 1 2 3 1 3 2 1 2
2 3 2 1

Sample Output

6
-1

Source

HDU 2007-Spring Programming Contest

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#include<stdio.h>
#include<iostream>
#include<string.h>
#include<algorithm>
using namespace std;
int s[1000005],t[10005];
int Next[1000005];
int ans;
void getNext(int b){
   int i=0,j=-1;
   Next[0]=-1;
   while(i<b){
      if(j==-1||t[i]==t[j]){
        i++;
        j++;
        Next[i]=j;
      }
    else
        j=Next[j];
   }
}
int kmp(int a,int b){
    int i=0,j=0,sum=0;
    while(i<a){
        if(j==-1||s[i]==t[j]){
            i++;
            j++;
        }
        else
            j=Next[j];
        if(j==b){
            ans=i+1-b;///该步需要特别注意一下即可
            return ans;
        }
    }
    return -1;
}
int main(){
   int tt;
   scanf("%d",&tt);
   while(tt--){
      memset(s,0,sizeof(s));
      memset(t,0,sizeof(t));
      memset(Next,0,sizeof(Next));
      int t1,t2;
      scanf("%d%d",&t1,&t2);
     int temp;
      for(int i=0;i<t1;i++){
         scanf("%d",&s[i]);
      }
           for(int i=0;i<t2;i++){
           scanf("%d",&t[i]);
           }
      getNext(t2);
      int pd;
      pd=kmp(t1,t2);
      printf("%d
",pd);

   }
   return 0;
}