【kmp】 剪花布条 HDU - 2087

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 
 4 char p[1005],s[1005];
 5 int  pLen,sLen,Next[1005],ans;
 6 
 7 void GetNext()  
 8 {  
 9     Next[0] = -1;  
10     int k = -1;  
11     int j = 0;  
12     while (j < pLen )  
13     {  
14         //p[k]表示前缀，p[j]表示后缀  
15         if (k == -1 || p[j] == p[k])   
16         {  
17             ++k;  
18             ++j;  
19             Next[j] = k;  
20         }  
21         else   
22         {  
23             k = Next[k];  
24         }  
25     }  
26 } 
27 
28 int KmpSearch()  
29 {  
30     int i = 0;  
31     int j = 0; 
32     int ans = 0; 
33  
34    
35     while (i !=sLen && j != pLen)  
36     {  
37         //①如果j = -1，或者当前字符匹配成功（即S[i] == P[j]），都令i++，j++      
38         if (j == -1 || s[i] == p[j])  
39         {  
40             i++;   
41             j++;  
42         }  
43         else  
44         {  
45             //②如果j != -1，且当前字符匹配失败（即S[i] != P[j]），则令 i 不变，j = next[j]      
46             //next[j]即为j所对应的next值        
47             j = Next[j];  
48         }  
49        
50            if(j == pLen) {
51                ans++;
52             j = 0;    
53         }     
54         
55     }  
56 
57     return ans;   
58 } 
59 
60 
61 int main() {
62     
63     while(~scanf("%s", s)&&s[0] != ‘#‘) {
64         ans = 0;
65         scanf("%s",p);
66         pLen = strlen(p);
67         sLen = strlen(s);
68         GetNext();
69         ans = KmpSearch();
70         printf("%d\n",ans);  
71     }
72      
73 }