题目链接 Problem Description Chiaki is interested in an infinite sequence $$$a_1,a_2,a_3,...,$$$ which is defined as follows: $$$a_n= \begin{cases} 1, & \text{$$$n=1,2$$$} \\ a_{n-a_{n-1}}+a_{n-1-a_{n-2}} & \text{$$$n\ge 3$$$} \end{cases}$$$ Chiaki wo…
主题链接:http://acm.hdu.edu.cn/showproblem.php?pid=4915 Parenthese sequence Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 131072/131072 K (Java/Others) Total Submission(s): 172 Accepted Submission(s): 69 Problem Description bobo found an anc…
题目链接:http://acm.hdu.edu.cn/showproblem.php? pid=4902 Nice boat Time Limit: 30000/15000 MS (Java/Others) Memory Limit: 131072/131072 K (Java/Others) Total Submission(s): 235 Accepted Submission(s): 116 Problem Description There is an old country…
题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=4925 Apple Tree Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 262144/262144 K (Java/Others) Total Submission(s): 188 Accepted Submission(s): 129 Problem Description I've bought an orchard an…
2019 Multi-University Training Contest 5 http://acm.hdu.edu.cn/contests/contest_show.php?cid=852 1004. Equation 把所有绝对值的零点排个序,然后解方程就好了. #include<bits/stdc++.h> using namespace std; // #define int long long void read(int &x) { x=0;int f=1;char ch=…
2019 Multi-University Training Contest 3 http://acm.hdu.edu.cn/contests/contest_show.php?cid=850 1004. Distribution of books 考虑二分答案,设当前二分出来的是\(x\). 设\(f_i\)表示前\(i\)个能分成最多的段数,使得每一段和都\(\leqslant x\). 转移显然,枚举一个\(j\),若\(s_i-s_j\leqslant x\)则转移,\(s_i\)表示前…
2019 Multi-University Training Contest 2 http://acm.hdu.edu.cn/contests/contest_show.php?cid=849 1005. Everything Is Generated In Equal Probability 考虑一个随机的排列的逆序对个数,显然对于两个数\(a,b\),他们位置是均匀排布的,也就是说有\(\frac{1}{2}\)的概率成为逆序对,并且是独立的. 所以一个长度为\(n\)的随机排列期望逆序对个…
