摘要: # T1 [方差](http://222.180.160.110:1024/contest/3917/problem/1) 观察式子:$\large\sum\limits_{i=1}^{N-1} \sum\limits_{j=i+1}^{N}\left|A_{i}-A_{j}\right|^{2}= 阅读全文
posted @ 2023-07-22 07:15 CloudWings 阅读(40) 评论(0) 推荐(0) 编辑