判断A是不是B的旋转字符串的3种方法

class Rotation {
public:
    bool chkRotation(string A, int lena, string B, int lenb) {
        // write code here
        if(lena != lenb)
            return true;
        string C;
        C = A + A;
        if(C.find(B,0) != -1)
            return true;
        return false;
    }
};

class Rotation {
public:
    bool chkRotation(string A, int lena, string B, int lenb) {
        // write code here
        if(lena != lenb)
            return false;
        string C = A + A;
        for(int i = 0; i < lena + lena;i++){
            if(C.substr(i,lenb) == B)
                return true;
        }
        return false;
    }
}

kmp匹配

class Rotation {
public:
    bool chkRotation(string A, int lena, string B, int lenb) {
        // write code here
        if(lena != lenb)
            return false;
        string C = A + A;
       int next[lenb];
//        int *next = new int[lenb];
        return kmp(C,B,next);
    }
        void makeNext(string B,int next[]){
            next[0] = 0;
            int k = 0;
            for(unsigned int i = 1; i < B.size();i++){
                while(k > 0 && B[i] != B[k])
                    k = next[k -1];
                if(B[i] == B[k])
                    ++k;
                next[i] = k;
            }
       }
         
        bool kmp(string C,string B,int next[]){
            makeNext(B,next);
           unsigned int lengthOfCompare = 0;
            for(unsigned int i = 0; i < C.size(); ++i){
                while(lengthOfCompare > 0 && C[i] != B[lengthOfCompare])
                    lengthOfCompare = next[lengthOfCompare - 1];
                if(B[lengthOfCompare] == C[i])
                    ++lengthOfCompare;
                if(lengthOfCompare == B.size())
                    return true;
            }
            return false;
        }
};