摘要: HDU6467 简单数学题 思路: 简单变换,先推式子 \[ F(n) = \sum_{i=1}^n (i \times \sum_{j=i}^n C_j^i)\\ = \sum_{i=1}^n i \times \sum_{j=i}^n{j \choose i}\\ =\sum_{j=1}^n\s 阅读全文
posted @ 2020-09-07 19:40 ファイナル 阅读(117) 评论(0) 推荐(0)
摘要: HDU6314 Matrix Problem Description Samwell Tarly is learning to draw a magical matrix to protect himself from the White Walkers. the magical matrix is 阅读全文
posted @ 2020-09-07 12:02 ファイナル 阅读(185) 评论(0) 推荐(0)
摘要: HDU6397 懒得搬题了 思路: 简单容斥+插板法 \[ {m+k-1\choose m-1}+\sum_{i=1}^m(-1)^i{m+k-ni-1\choose m-1}{m\choose i} \] \(\mathfrak{Talk\ is\ cheap,show\ you\ the\ co 阅读全文
posted @ 2020-09-07 10:41 ファイナル 阅读(154) 评论(0) 推荐(0)
摘要: HDU 6755 Fibonacci Sum Problem Description The Fibonacci numbers are defined as below: \[ \] \begin F_{0}=0, F_{1}=1 \ F_=F_+F_(n>1) \end \[ Given thr 阅读全文
posted @ 2020-09-07 09:18 ファイナル 阅读(206) 评论(0) 推荐(0)