这道题其实是分层图,但和裸的分层图不太一样.因为它只要求路径总权值为路径上最大一条路径的权值,但仔细考虑,这同时也满足一个贪心的性质,那就是当你每次用路径总权值小的方案来更新,那么可以保证新的路径权值尽量小. 所以这道题在不删边的情况下可以使用Dij来跑,而删边权的情况就是分层图. 所以就拿分层图来搞好了^_^. 由于这个数据p和k都比较大,所以直接建k+1层图是要爆的,而k+1层图边都一样,我们就用dis[层数(0-k)]来表示. 具体的就是每次Dij转移是要分两种情况: 1.在原层跑,也就是…

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 the cables required to connect his farm to the phone system. There a…

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 the cables required to connect his farm to the phone system. There a…

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…

P1948 [USACO08JAN]电话线Telephone Lines 题意 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 the cables required to connect his farm to the phone system. Ther…

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 the cables required to connect his farm to the phone system. There are N (1 ≤ N ≤ 1,000) forlorn telephon…

多年以后,笨笨长大了,成为了电话线布置师.由于地震使得某市的电话线全部损坏,笨笨是负责接到震中市的负责人.该市周围分布着N(1<=N<=1000)根据1……n顺序编号的废弃的电话线杆,任意两根线杆之间没有电话线连接,一共有p(1<=p<=10000)对电话杆可以拉电话线.其他的由于地震使得无法连接. 第i对电线杆的两个端点分别是ai,bi,它们的距离为li(1<=li<=1000000).数据中每对(ai,bi)只出现一次.编号为1的电话杆已经接入了全国的电话网络,整个…

题面 题解 很显然,答案满足单调性. 因此,可以使用二分答案求解. 考虑\(check\)的实现. 贪心地想,免费的\(k\)对电话线一定都要用上. 每次\(check\)时将小于\(mid\)的边权设为\(0\),其它的设为\(1\). 跑一边最短路判断\(\mathrm{dist[n]}\)是否\(\leq k\)即可. 代码 #include <bits/stdc++.h> #define itn int #define gI gi using namespace std; inline…

#\(\mathcal{\color{red}{Description}}\) \(Link\) 给定一个图,请你求出在把其中自由选择的\(k\)条的权值都置为零的情况下,图中\(1-N\)最短路上的最大边权的最小值. #\(\mathcal{\color{red}{Solution}}\) 哇这个题真是吊打我的智商啊- 首先我们看题目中给的限制条件,限制我们不能直接\(sort\)一遍的条件就是我们要找的是最短路上的边权最大值最小限制了我们把一些边的权值置为零之后,图上的最短路.而这个最短路的…

二分+dij题目 首先读一遍题目,一定要仔细读(不要问我为什么,我就是受害者qwq 你会发现最终的费用是由最长的电话线决定的,而非电话线长度和. 至此就有了一个基本思路--枚举(二分)出可能的最长电话线长度,然后对其进行dij判断. dij思路如下: 1.已知枚举出了假定答案ans: 2.在最短路过程中,判断有多少条线长度大于ans,并将其免费: 3.最后判断免费条数,若大于给出的t即不可行,反之可行. 开long long!!! 代码: #include<bits/stdc++.h> usi…