转自:http://apfelmus.nfshost.com/articles/monoid-fingertree.html This post grew out of the big monoid discussion on the haskell-cafe mailing list. Introduction A very powerful application of monoids are 2-3 finger trees, first described by Ralf Hinze a…

http://staff.city.ac.uk/~ross/papers/FingerTree.html Summary We present 2-3 finger trees, a functional representation of persistent sequences supporting access to the ends in amortized constant time, and concatenation and splitting in time logarithmi…

"I worked up a full implementation as well but I decided that it was too complicated to post in the blog. What I was really trying to get across was that immutable data structures were possible and not that hard; a full-on finger tree implementation…

C# 知识回顾 - 表达式树 Expression Trees 目录 简介 Lambda 表达式创建表达式树 API 创建表达式树 解析表达式树 表达式树的永久性 编译表达式树 执行表达式树 修改表达式树 调试 简介 表达式树以树形数据结构表示代码,其中每一个节点都是一种表达式,比如方法调用和 x < y 这样的二元运算等. 你可以对表达式树中的代码进行编辑和运算.这样能够动态修改可执行代码.在不同数据库中执行 LINQ 查询以及创建动态查询.  表达式树还能用于动态语言运行时 (DLR) 以提…

题意: 给n*m个点(1 ≤ m, n ≤ 1e5),左下角的点为(1,1),右上角的点(n,m),一个人站在(0,0)看这些点.在一条直线上,只能看到最前面的一个点,后面的被档住看不到,求这个人能看到多少个点. 知识点: 容斥原理:(容许) 先不考虑重叠的情况,把包含于某条件中的所有对象的数目先计算出来,(排斥)然后再把计数时重复计算的数目排斥出去,使得计算的结果既无遗漏又无重复. 公式:          奇加偶减 一般求互质个数若用欧拉函数不好解决,则从反面考虑,用容斥. 模板: void…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 这道题实际上是Catalan Number卡塔兰数的一个例子,如果对卡塔兰数不熟悉的童鞋可能真…

Given n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example,Given n = 3, your program should return all 5 unique BST's shown below. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 confused what "{1,#,2…

Given n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example, Given n = 3, your program should return all 5 unique BST's shown below. 1               3            3             2             1 \          …

Linux finger命令 Linux finger命令可以让使用者查询一些其他使用者的资料.会列出来的资料有: Login Name User Name Home directory Shell Login status mail status .plan .project .forward 其中 .plan..project 和 .forward 就是使用者在他的 Home Directory 里的 .plan , .project 和 .forward 等档案里的资料.如果没有就没有.f…