\(\text{link}\) 。很困难的二进制计数。 前置知识 \(1\):范德蒙德卷积推广。 即 \(\sum\limits_{\sum \limits_{i=1}^n a_i=n}\)本栏目推荐文章CF414B - Mashmokh and ACMCF-613-DCF1201C - Maximum MedianAT_arc125_c [ARC125C] LIS to Original Sequence 题解P5321 [BJOI2019] 送别 题解--zhengjunCF1876D LexichromatographyP9007 [入门赛 #9] 最澄澈的空与海 (Hard Version) 题解P2198 杀蚂蚁 题解P3243 [HNOI2015] 菜肴制作 题解AT_abc243_g [ABC243G] Sqrt题解题解 1770F 1770 CF题解1770f cf 1770c cf 2022 2023 1770 1770c 1770f sequence 1770f koxia and 恒等式codeforces sequence 1770f 题解cf 题解1900e cf 题解1896e cf