题意             n个数1~n按顺序围成一个圈...现在在某些两点间加边..边可以加在圈内或者圈外..问是否会发生冲突?如果不发生冲突..输每一条边是放圈内还是圈外.     题解             这道题和POJ 3207差不多了..只是那道题只要判断是否存在不要输出方案...发现个很严重的问题..POJ 3207的数据实在是太弱了..我上一个程序里判断两个线段是否相交是个错了..都让我AC了..导致我做这题是沿用了思路...浪费了很多时间...          …

A. Ring road time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Nowadays the one-way traffic is introduced all over the world in order to improve driving safety and reduce traffic jams. The g…

http://codeforces.com/contest/738/problem/C Vasya is currently at a car rental service, and he wants to reach cinema. The film he has bought a ticket for starts in t minutes. There is a straight road of length s from the service to the cinema. Let's…

Road to Post Office 题意: 一个人要从0走到d,可以坐车走k米,之后车就会坏,你可以修或不修,修要花t时间,坐车单位距离花费a时间,走路单位距离花费b时间,问到d的最短时间. 题解: 首先要分成k段,k段的总长是ovmod,每一段可以选择修车坐车或选择走路,(只有第一段的时候不用修车),最后在加上剩下的那些路的时间,剩下的是mod,(可以选择修车坐车或选择走路)最后min答案就好了.但其中还有一种情况要注意,就是前ovmod也可以选择坐车之后不修走着,所以这种要特殊处理下.…

D. Road to Post Office time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Vasiliy has a car and he wants to get from home to the post office. The distance which he needs to pass equals to d ki…

题目:http://codeforces.com/problemset/problem/543/D 题意:给你一棵树,一开始边都是0,可以使任意的边变成1,对于每一个根节点求使得它到其他任一点的路径上只有一条0边的方案数. 假设只求一个根,f[u]=∏(s[v]+1) 然后移动根节点这样就可以通过遍历一遍树得到所有点的答案了. s[v]=(s[u]/(s[v]+1)+1)*s[v] 这样当前根和根的其他子树就变成v的子树了(前面那坨就是它的贡献.. (看起来是这样没错..但是不能求逆元.因为s[…

本文版权归ljh2000和博客园共有,欢迎转载,但须保留此声明,并给出原文链接,谢谢合作. 本文作者:ljh2000 作者博客:http://www.cnblogs.com/ljh2000-jump/转载请注明出处,侵权必究,保留最终解释权! 题目链接:CF27D 正解:$2—SAT$ 解题报告: 也是$2-SAT$裸题,判断线段相交之后,直接上$2-SAT$就好了. 但是判线段相交有一点难受啊,换了几种写法才搞对,最好是双向判断一下…' 注意输出方案的时候一般的做法就是将图反向之后拓扑排序,一…

Berland has n cities, some of them are connected by bidirectional roads. For each road we know whether it is asphalted or not. The King of Berland Valera II wants to asphalt all roads of Berland, for that he gathered a group of workers. Every day Val…

题目链接: D. Road to Post Office time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Vasiliy has a car and he wants to get from home to the post office. The distance which he needs to pass equals t…

题目描述 Vasiliy has a car and he wants to get from home to the post office. The distance which he needs to pass equals to ddkilometers. Vasiliy's car is not new — it breaks after driven every kk kilometers and Vasiliy needs tt seconds to repair it. Afte…