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++; } } };