G - Number Sequence

Posted 2020-09-30 小小超plus

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. 

InputThe 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]. 
OutputFor 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
KMP（看毛片）算法

 1 #include <iostream>
 2 using namespace std;
 3 #include<string.h>
 4 #include<set>
 5 #include<stdio.h>
 6 #include<math.h>
 7 #include<queue>
 8 #include<map>
 9 #include<algorithm>
10 #include<cstdio>
11 #include<cmath>
12 #include<cstring>
13 #include <cstdio>
14 #include <cstdlib>
15 #include<cstring>
16 int a1[10010];
17 int a[10010],b[1000010];
18 int t,lena,lenb;
19 void KMPdebiao()
20 {
21     a1[0]=-1;
22     int j=0,k=-1;
23     while(j<lena-1)
24     {
25         if(k==-1||a[j]==a[k])
26         {
27             j++;
28             k++;
29             a1[j]=k;
30         }
31         else
32             k=a1[k];
33     }
34 }
35 int KMP()
36 {
37     int j=0;
38     int i=0;
39     KMPdebiao();
40     while(i<lenb)
41     {
42 
43         if(j==-1||a[j]==b[i])
44         {
45             j++;
46             i++;
47         }
48         else
49         {
50             j=a1[j];
51         }
52         if(j==lena)
53             return i-lena+1;
54     }
55     return -1;
56 }
57 int main()
58 {
59     cin>>t;
60     int i;
61     while(t--)
62     {
63         cin>>lenb>>lena;
64         memset(a1,0,sizeof(a1));
65         memset(a,0,sizeof(a));
66         memset(b,0,sizeof(b));
67         for(i=0;i<lenb;i++)
68             cin>>b[i];
69         for(i=0;i<lena;i++)
70             cin>>a[i];
71         cout<<KMP()<<endl;
72     }
73     return 0;
74 }

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