算法笔记 --- String Rotation

class Rotation {
 
public:
    bool chkRotation(string A, int lena, string B, int lenb) {
        if(lena != lenb)
            return false;
        
        string str_target = A + A;
        if(KMP_Find(str_target, B))
            return true;
        else
            return false;
        
    }
    bool KMP_Find(string& s,string& t)  
    {  
         int i=0,j=0;  
         int n =t.size();  
         int *next = new int[n];  
         GetNext(t,next);  
         while(i<s.size()&&j<t.size())  
          {  
             if((j == 0)||(s.at(i)==t.at(j)))  
            {  
                  i++;  
                j++;  
            }else{  
                j = next[j];  
            }  
           }
        if(j==t.size())  
          {  
               //int index=i-t.size()+1;  
               //cout<<"子串从长串的第"<<index<<"位开始匹配成功!"<<endl;    
               return true;  
          }  
         //cout<<"字符串匹配失败!"<<endl; 
          return false;  
    }
    void GetNext(string& s,int *next)  
    {  
        int len = s.size();  
         next[0] = 0;  
         next[1] = 0;  
         int i = 1;  
         while(i < len - 1)  
        {  
            int j = next[i];  
  
            while(j > 0 && s.at(j) != s.at(i)) j = next[j];  
  
            if(s.at(j) == s.at(i))  next[i + 1] = j + 1;  
            else next[i + 1] = j;  
  
            i++;  
          } 
    } 
};