版权声明：SupremeBeast3_ https://blog.csdn.net/weixin_43359312/article/details/89018783
cin效率
以下行代码可取消cin与scanf同步，从而增大cin效率
std::ios::sync_with_stdio(false)
参考网站
https://www.cnblogs.com/xienaoban/p/6798095.html
https://www.byvoid.com/zhs/blog/fast-readfile
http://www.cnblogs.com/killerlegend/p/3918452.html ⚀