Problem Description Josh Lyman is a gifted painter. One of his great works is a glass painting. He creates some well-designed lines on one side of a thick and polygonal glass, and renders it by some special dyes. The most fantastic thing is that it c…

Problem Description City C is really a nightmare of all drivers for its traffic jams. To solve the traffic problem, the mayor plans to build a RTQS (Real Time Query System) to monitor all traffic situations. City C is made up of N crossings and M roa…

Description Could you imaging a monkey writing computer programs? Surely monkeys are smart among animals. But their limited intelligence is no match for our human beings. However, there is a theorem about monkeys, and it states that monkeys can write…

Description Aliens on planet Pandora also write computer programs like us. Their programs only consist of capital letters (‘A’ to ‘Z’) which they learned from the Earth. On planet Pandora, hackers make computer virus, so they also have anti-virus sof…

感慨一下,区域赛的题目果然很费脑啊!!不过确实是一道不可多得的好题目!! 题目大意:给你一棵有n个节点的树,让你移动树中一条边的位置,即将这条边连接到任意两个顶点(边的大小不变),要求使得到的新树的直径最小. 解题思路:此题先求出原始树的直径maxr1,并记录直径上的各个节点.很容易想到要移动的边一定是直径上的边,只有这样才有可能使树的直径减小!! 接着就是枚举直径上的每条边,并用这条边作为分隔将原始树分割成两棵子树(即子树一和子树二),然后分别求子树一的直径maxr2 和子树二的直径maxr3…

Description You are given an undirected graph with N vertexes and M edges. Every vertex in this graph has an integer value assigned to it at the beginning. You're also given a sequence of operations and you need to process them as requested. Here's a…

Description Plain of despair was once an ancient battlefield where those brave spirits had rested in peace for thousands of years. Actually no one dare step into this sacred land until the rumor that “there is a huge gold mine underneath the plain” s…

Description     A new Semester is coming and students are troubling for selecting courses. Students select their course on the web course system. There are n courses, the ith course is available during the time interval (Ai,Bi). That means, if you wa…

Description Math Olympiad is called “Aoshu” in China. Aoshu is very popular in elementary schools. Nowadays, Aoshu is getting more and more difficult. Here is a classic Aoshu problem: ABBDE __ ABCCC = BDBDEIn the equation above, a letter stands for a…

Description “Farm Game” is one of the most popular games in online community. In the community each player has a virtual farm. The farmer can decide to plant some kinds of crops like wheat or paddy, and buy the corresponding crop seeds. After they gr…