KMP

http://acm.hdu.edu.cn/showproblem.php?pid=1711
 1 #include<iostream>
 2 using namespace std;
 3 int nx[10000+5], b[10000+5], a[1000000+5];
 4 int n, m;
 5 void getnext(){
 6     int k = -1, j = 0;
 7     nx[0] = -1;
 8     while(j < m){
 9         if(k == -1 || b[j] == b[k]) nx[++j] = ++k;
10         else k = nx[k];
11     }
12 }
13 int KMP()
14 {
15     int flag = -1;
16     for(int i = 0, j = 0; i < n; i++){
17         while(j > 0 && b[j] != a[i]) j = nx[j];
18         if(a[i] == b[j]) j++;
19         if(j == m)
20         {
21             return i - j + 2;
22         }
23     }
24     return -1;
25 }
26 int main()
27 {
28     ios::sync_with_stdio(0);
29     cin.tie(0);
30     cout.tie(0);
31     int t;
32     cin >> t;
33     while(t--){
34         cin >> n >> m;
35         for(int i = 0; i < n; i++) cin >> a[i];
36         for(int i = 0; i < m; i++) cin >> b[i];
37         getnext();
38         cout << KMP() << endl;
39     }
40     return 0;
41 }
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