二分答案+单源最短路 POJ原题链接 洛谷原题链接 显然可以二分答案,检验\(mid\)可以使用最短路来解决. 将大于\(mid\)的边看成长度为\(1\)的边,说明要使用免费升级服务,否则长度为\(0\)边,即不需要占免费的资格. 然后就可以在上面跑最短路,如果\(dis[n]>k\)说明该答案不可行,将答案改大,否则说明可行,往小的去尝试. 而针对长度只有\(0,1\)的图可以使用双端队列的\(BFS\)来解决,不过我这种懒人就直接跑\(SPFA\)了. #include<cstdio&g…

二分+特殊姿势的check:二分最小代价P,把边权小于等于P的边设为0,其他的设为1,跑一遍最短路,判断dis[n]是否大于K #include<cstdio> #include<algorithm> #include<cstring> #include<queue> using namespace std; ; ,Maxdis=,last[maxn],dis[maxn]; bool v[maxn]; struct edge{int to,pre,dis;}…

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…

POJ3662 Telephone Lines 题目大意:要在顶点1到顶点n之间建一条路径,假设这条路径有m条边,其中有k条边是免费的,剩余m-k条边是要收费的, 求这m-k条边中花费最大的一条边的最小花费. 让m条边中原本花费最大的k条边成为免费的边,则这时m-k条边中花费最大的一条边的花费最小. 二分枚举m-k条边中花费最大的一条边的最小花费x,dijkstra求最短路径时,将花费大于x的边的花费设为1(花费为INF的边不变),花费小于等于x的边设为 0,则d[v-1]中返回的就是花费大于x…

链接:洛谷 POJ 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) forlor…

http://poj.org/problem?id=3662 Telephone Lines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions:9310   Accepted: 3374 Description Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative,…

洛谷 P1948 [USACO08JAN]电话线Telephone Lines https://www.luogu.org/problem/P1948 JDOJ 2556: USACO 2008 Jan Silver 3.Telephone Lines https://neooj.com/oldoj/problem.php?id=2556 题目描述 Farmer John wants to set up a telephone line at his farm. Unfortunately, t…

题目背景 (USACO 5.3.4) 题目描述 农夫约翰想要在他的正方形农场上建造一座正方形大牛棚.他讨厌在他的农场中砍树,想找一个能够让他在空旷无树的地方修建牛棚的地方.我们假定,他的农场划分成 N x N 的方格.输入数据中包括有树的方格的列表.你的任务是计算并输出,在他的农场中,不需要砍树却能够修建的最大正方形牛棚.牛棚的边必须和水平轴或者垂直轴平行. EXAMPLE 考虑下面的方格,它表示农夫约翰的农场,‘.'表示没有树的方格,‘#'表示有树的方格 1 2 3 4 5 6 7 8 1 .…