微软面试题 之 "Add back spaces" 有两个string,str1 = "i am a boy", str2 = "iamaboy"写出下面函数的实现char* AddBackSpaces(const char* str, const set<string>& words){ ...}传入的str是"iamaboy",words是["i", "am", "a", "boy"],期望的输出是"i am a boy".