https://blog.csdn.net/c6376315qqso/article/details/81130241


https://blog.csdn.net/Coldfresh/article/details/81122267
https://blog.csdn.net/coldfresh/article/details/74117650


cf 暴力 https://blog.csdn.net/litmxs/article/details/74182326


树状数组查询区间内不同数的个数基本操作 http://www.cnblogs.com/chenquanwei/articles/9340577.html
https://blog.csdn.net/thinfatty/article/category/6927499 莫队算法


拉格朗日插值
http://www.ebola.pro/article/notes/Lagrange
小凯的疑惑 https://www.zhihu.com/question/67960150

牛客网直播链接https://www.nowcoder.com/live/167/3/1