Mathematica是个好东西。虽然早有耳闻功能强大，但是没想到强大到这种地步。 原本因为课程原因，研究了一下如何在Mathematica里绘制股票数据。不过现在停止，只完成了一小部分。剩下的……想折腾的话，按照已经有的代码，能容易改出来其他功能。 数据来源 首先要说的是，Mathematica中自行提供了非权威的金融数据。这对我们很方便。 使用命令FinancialData,就可以获取大量需

技巧 自然溢出 自然溢出不会影响低位数据,所以有的时候你不需要取模,而是一个unsigned. 除法取模 对于式子 a×bcmod  p≡a×bmod  cpc\frac {a \times b}{c} \mod p \equiv \frac{a \times b \mod cp}{c} ca×b​modp≡ca×bmodcp​ 细节 注意数据类型,例如6*(ll)(1<<

You are given a string S consisting of only lowercase english letters and some queries. For each query (l,r,k), please output the starting position of the k-th occurence of the substring SlSl+1…Sr in

You are given an array a1,a2,…,an(∀i∈[1,n],1≤ai≤n). Initially, each element of the array is unique. Moreover, there are m instructions. Each instruction is in one of the following two formats: (1,pos

内容有复制和参考。 这篇文章主要用于记录在探索评测系统Reef期间我所学的东西,以便之后查阅. Reef预计主要支持远程评测 加一点本地评测…

n个有标号的球围成一个圈。每个球有两种颜色可以选择黑或白染色。问有多少种方案使得没有出现连续白球7个或连续黑球7个。 对方案数mod 2015，球最多有100000个。 分析 考虑对于非环状球的答案计算，可以设sum(i,k)sum(i,k)sum(i,k)表示第i个球为k色时的方案数。其计算非常显然 sum(i,k)=∑1≤j≤6sum(i−j,1−k)sum(i,k)=\sum_{1\leq

There are n pirate chests buried in Byteland, labeled by 1,2,…,n. The i-th chest’s location is (xi,yi), and its value is wi, wi can be negative since the pirate can add some poisonous gases into the c

为了做课件又加了很多东西。 对于可以离线的区间询问问题，莫队算法提出了一种可以在O(nn)O(n\sqrt n)O(nn​)(无修改)，O(n5/3)O(n^{5/3})O(n5/3)(带修改)内得出答案的方法。 主要的思路是对询问离线并分块，利用在2个区间间答案的快速转移（如果无法找到快速转移的方法，就没法用了）降低复杂度。

zz6d likes reading very much, so he bought a lot of books. One day, zz6d brought n books to a classroom in school. The books of zz6d is so popular that K students in the classroom want to borrow his b

Farmer John keeps a website called ‘FansBlog’ .Everyday , there are many people visited this blog.One day, he find the visits has reached P , which is a prime number.He thinks it is a interesting fact