代码如下：
//O(N^2) vector<string> getAllSubString(string str){ vector<string>arr; string m; int i,num; for(int len = 1; len <= str.size(); len++){ i = num = 0; m.clear(); while(num < str.size() && i < str.size()){ m += str[i]; if(m.size() == len){ //str中字符可能相同 if(find(arr.begin(), arr.end(), m) == arr.end()){ arr.push_back(m); } // arr.push_back(m); //str中各字符均不相同 m.clear(); i = (++num); }else{ i++; } } } return arr; }