亲和串（HDU2203）

http://acm.hdu.edu.cn/showproblem.php?pid=2203

题目意思很简单，求s1串所构成的环中是否有s2这个串

用CMP参考http://s.acmore.net/show_article/show/44

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <iostream>
 #include <stack>
 #include <set>
 #include <queue>
 #define MAX(a,b) (a) > (b)? (a):(b)
 #define MIN(a,b) (a) < (b)? (a):(b)
 #define mem(a) memset(a,0,sizeof(a))
 #define INF 1000000007
 #define MAXN 100005
 using namespace std;

 char a[*MAXN],b[MAXN];
 int next[MAXN];

 void get_next()
 {
     next[]=-;
     int key = -;
     int index = ;
     int len =strlen(b);
     while(index < len-)
     {
         if(key == - || b[index] == b[key])
         {
             next[++index] = ++key;
         }
         else{
             key = next[key];
         }
     }
 }

 int KMP()
 {
     int A=,B=;
     int len1 = strlen(a);
     int len2 = strlen(b);
     while(A<len1 && B<len2)
     {
         if(B==- || a[A] == b[B])
         {
             A++;B++;
         }
         else
         {
             B=next[B];
         }
     }
     if(B >= len2)return ;
     return ;
 }

 int main()
 {
     while(~scanf("%s%s",a,b))
     {
         int len = strlen(a);
         for(int i=; i<len; i++)
         {
             a[len+i] = a[i];
         }
         get_next();
         printf("%s\n",KMP()?"yes":"no");
     }
     return ;
 }