hdu1711 kmp

 1 #include<stdio.h>
 2 #include<string.h>
 3 int a[1000005],b[1000005],next[100005];
 4 int main()
 5 {
 6     int t,i,j,n,m;
 7     while (~scanf("%d",&t))
 8     while (t--)
 9     {
10         scanf("%d%d",&n,&m);
11         for (i=1;i<=n;i++) scanf("%d",&a[i]);
12         for (i=1;i<=m;i++) scanf("%d",&b[i]);
13         //先求next数组 
14         i=1; next[1]=0; j=0;
15         while (i<=m)
16         {
17             if (j==0||b[i]==b[j]) {i++; j++; 
18                 if (b[i]!=b[j]) next[i]=j; else next[i]=next[j]; }
19             else j=next[j];
20         }
21         //KMP
22         i=1; j=1;
23         while (i<=n&&j<=m)
24         {
25             if (j==0||a[i]==b[j]) {i++; j++; }
26             else j=next[j]; 
27         }
28         //OK
29         if (j>m) printf("%d\n",i-m);
30         else printf("-1\n");
31     }
32     return(0);
33 } 

http://acm.hdu.edu.cn/showproblem.php?pid=1711