题目链接:http://poj.org/problem?id=3662 Telephone Lines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 8248   Accepted: 2977 Description Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncoopera…

题意:有N个独立点,其中有P对可用电缆相连的点,要使点1与点N连通,在K条电缆免费的情况下,问剩下的电缆中,长度最大的电缆可能的最小值为多少. 分析: 1.二分临界线(符合的情况的点在右边),找可能的最小值,假设为mid. 2.将大于mid的边变为1,小于等于mid的边变为0(表示这些边由自己承包),由此算出1~N的最短路长度为x.x即为所用的大于mid的电缆个数. 3.若x<=K,则符合情况,但是想让所用的免费电缆条数x更多,所以让mid更小一些,这样自己承包的边也减少,x将更大,即r = m…

Telephone Lines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 7214   Accepted: 2638 Description Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative, so he needs to pay for some of…

Telephone Lines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 6973   Accepted: 2554 Description Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative, so he needs to pay for some of…

意甲冠军: 到n节点无向图,它要求从一个线1至n路径.你可以让他们在k无条,的最大值.如今要求花费的最小值. 思路: 这道题能够首先想到二分枚举路径上的最大值,我认为用spfa更简洁一些.spfa的本质是一种搜索算法,既然是搜索,就涉及到状态的转移. 在一般求最短路的spfa算法中,当到结点u时,对e(u,v)仅仅需做例如以下转移:if(d[v]>d[u]+w(e)) d[v]=d[u]+w(e).在跟一般的情况下.到结点u,对e(u,v)需做多种转移.比方这题中要考虑让e免费和不让e免费两种情…

Telephone Lines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 7115   Accepted: 2603 Description Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative, so he needs to pay for some of…

目录 题面 题目链接 题目描述 输入输出格式 输入格式 输出格式 输入输出样例 输入样例 输出样例 说明 思路 AC代码 题面 题目链接 P1948 [USACO08JAN]电话线Telephone Lines 题目描述 Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative, so he needs to pay for some of…

Telephone Lines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 6785   Accepted: 2498 Description Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative, so he needs to pay for some of…

Telephone Lines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 5696   Accepted: 2071 Description Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative, so he needs to pay for some of…

<题目链接> 题目大意: 在一个节点标号为1~n的无向图中,求出一条1~n的路径,使得路径上的第K+1条边的边权最小. 解题分析:直接考虑情况比较多,所以我们采用二分答案,先二分枚举第K+1条路的边权,然后根据枚举的边权,重新建图.因为john只需要支付除K条边之后权值最大的边,所以对于所有边权小于等于枚举边的,将其边权置为0,对于那些大于枚举边权的边,边权则置为1,这样,对1~n跑最短路,就能够用于判断枚举的答案是否成立.因为建的是边权为0.1的图求最短路,所以也可以用双端队列实现的BFS求…