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…

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,…

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 telephone pol…

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…

思路: 二分+最短路.最短路也可以用来计算从a到达b所需的边权不超过x的边的数量. 实现: #include <cstdio> #include <cmath> #include <queue> #include <cstring> using namespace std; const int INF = 0x3f3f3f3f; ; int G[MAXN][MAXN], d[MAXN]; bool in[MAXN]; int n, p, k; int spf…

题目传送门 题意:有n个点, p条路,每条道路有个花费Li, 然后现在要建一条1-n的路线,然后可以选k条道路免费, 然后可以在剩下的道路中选择价格最高的边支付费用, 求这个答案最小. 题解: 二分答案. 每次check过程中, 一条边的花费 <= mid 则 路径长度为0,否者路径长度为1.然后 求 到n的点之后长度<=k. 然后就是bfs的过程中. 如果这条边是0, 那么从前入队, 否者从后入队. 代码: #include<cstdio> #include<algorit…

1614: [Usaco2007 Jan]Telephone Lines架设电话线 Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 892  Solved: 399[Submit][Status] Description Farmer John打算将电话线引到自己的农场,但电信公司并不打算为他提供免费服务.于是,FJ必须为此向电信公司支付一定的费用. FJ的农场周围分布着N(1 <= N <= 1,000)根按1..N顺次编号的废弃的电话线杆,任意两…

题目 1614: [Usaco2007 Jan]Telephone Lines架设电话线 Time Limit: 5 Sec  Memory Limit: 64 MB Description Farmer John打算将电话线引到自己的农场,但电信公司并不打算为他提供免费服务.于是,FJ必须为此向电信公司支付一定的费用. FJ的农场周围分布着N(1 <= N <= 1,000)根按1..N顺次编号的废弃的电话线杆,任意两根电话线杆间都没有电话线相连.一共P(1 <= P <= 10…

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…

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…