C++ map排序
std::map<int,std::string,std::less<int>> map; //升序(默认的)
std::map<int,std::string,std::greater<int>> map; //降序
参考:https://blog.csdn.net/sandalphon4869/article/details/105419706
https://blog.csdn.net/web17886480312/article/details/123614757