HDU1686 KMP

题意：一个字符串在另一个字符串中出现的次数
View Code
 1 #include<stdio.h>
 2 #include<string.h>
 3 const int maxn = 10005;
 4 const int maxm= 1000005;
 5 int lena,lenb;
 6 char a[ maxm ],b[ maxn ];
 7 int next[ maxn ];
 8 int ans;
 9 void getNext(){
10     int j,k;
11     j=0,k=-1;
12     next[0]=-1;
13     while( j<lenb ){
14         if( k==-1||b[j]==b[k] )
15             j++,k++,next[ j ]=k;
16         else k=next[ k ];
17     }
18 }
19 int kmp(){
20     getNext();
21     int i,j;
22     i=j=0;
23     while( i<lena&&j<lenb ){
24         if( j==-1||a[i]==b[j] )
25             i++,j++;
26         else j=next[j];
27         if( j==lenb ){
28             ans++;
29             j=next[j];
30         }
31     }
32     return ans;
33 }
34 int main(){
35     int t;
36     scanf("%d",&t);
37     while(t--){
38         scanf("%s",b);
39         scanf("%s",a);
40         lena=strlen(a),lenb=strlen(b);
41         ans=0;
42         printf("%d\n",kmp());
43     }
44     return 0;
45 }
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