(poj) 1751 Highways
Description The island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has a very poor system of public highways. The Flatopian government is aware of this problem and has already constructed a number of highways connecting some of the most important towns. However, there are still some towns that you can't reach via a highway. It is necessary to build more highways so that it will be possible to drive between any pair of towns without leaving the highway system. Flatopian towns are numbered from 1 to N and town i has a position given by the Cartesian coordinates (xi, yi). Each highway connects exaclty two towns. All highways (both the original ones and the ones that are to be built) follow straight lines, and thus their length is equal to Cartesian distance between towns. All highways can be used in both directions. Highways can freely cross each other, but a driver can only switch between highways at a town that is located at the end of both highways. The Flatopian government wants to minimize the cost of building new highways. However, they want to guarantee that every town is highway-reachable from every other town. Since Flatopia is so flat, the cost of a highway is always proportional to its length. Thus, the least expensive highway system will be the one that minimizes the total highways length.
Input The input consists of two parts. The first part describes all towns in the country, and the second part describes all of the highways that have already been built. The first line of the input file contains a single integer N (1 <= N <= 750), representing the number of towns. The next N lines each contain two integers, xi and yi separated by a space. These values give the coordinates of ith town (for i from 1 to N). Coordinates will have an absolute value no greater than 10000. Every town has a unique location. The next line contains a single integer M (0 <= M <= 1000), representing the number of existing highways. The next M lines each contain a pair of integers separated by a space. These two integers give a pair of town numbers which are already connected by a highway. Each pair of towns is connected by at most one highway.
Output Write to the output a single line for each new highway that should be built in order to connect all towns with minimal possible total length of new highways. Each highway should be presented by printing town numbers that this highway connects, separated by a space. If no new highways need to be built (all towns are already connected), then the output file should be created but it should be empty.
Sample Input 9
1 5
0 0
3 2
4 5
5 1
0 4
5 2
1 2
5 3
3
1 3
9 7
1 2
Sample Output 1 6
3 7
4 9
5 7
8 3 题意:有N个点,给N个坐标,M条路,表示a和b已经连通,问还需要连通哪几个点,使所有点都连通并且路径最短 方法:开始有并查集写,但是超时了,数据太大,然后改用最小生成树写
#include <iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include <math.h>
#include<queue>
#define ll long long
#define INF 0x3f3f3f3f
#define met(a,b) memset(a,b,sizeof(a));
#define N 800
using namespace std;
int Map[N][N],dis[N];
int a[N],b[N],vis[N],s[N];
int n;
void init()///计算任意两点之间的距离 双向
{
for(int i=; i<=n; i++)
{
for(int j=i+; j<=n; j++)
Map[i][j]=Map[j][i]=((a[i]-a[j])*(a[i]-a[j])+(b[i]-b[j])*(b[i]-b[j]));
}
}
void prime(int u)
{
met(vis,);
met(dis,);
for(int i=; i<=n; i++)
{
dis[i]=Map[u][i];
s[i]=;
}
vis[u]=;
for(int i=; i<n; i++)
{
int an=INF,k;
for(int j=; j<=n; j++)
if(!vis[j] && an>dis[j])
an=dis[k=j];
if(an!=)///如果等于0 说明已经连接
{
printf("%d %d\n",s[k],k);
}
vis[k]=;
for(int j=; j<=n; j++)
{
if(!vis[j] && dis[j]>Map[k][j])
{
dis[j]=Map[k][j];
s[j]=k;///随时更改与k相连最短的点
}
}
}
}
int main()
{
int m,x,y;
while(scanf("%d",&n)!=EOF)
{
for(int i=; i<=n; i++)
{
scanf("%d %d",&a[i],&b[i]);
}
init();
scanf("%d",&m);
for(int i=; i<m; i++)
{
scanf("%d %d",&x,&y);
Map[x][y]=Map[y][x]=; }
prime();
}
return ;
}
(poj) 1751 Highways的更多相关文章
- POJ 1751 Highways (最小生成树)
Highways Time Limit:1000MS Memory Limit:10000KB 64bit IO Format:%I64d & %I64u Submit Sta ...
- POJ 1751 Highways (最小生成树)
Highways 题目链接: http://acm.hust.edu.cn/vjudge/contest/124434#problem/G Description The island nation ...
- POJ 1751 Highways (kruskal)
题目链接:http://poj.org/problem?id=1751 题意是给你n个点的坐标,然后给你m对点是已经相连的,问你还需要连接哪几对点,使这个图为最小生成树. 这里用kruskal不会超时 ...
- POJ 1751 Highways (ZOJ 2048 ) MST
http://poj.org/problem?id=1751 http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=2048 题目大 ...
- POJ 1751 Highways 【最小生成树 Kruskal】
Highways Time Limit: 1000MS Memory Limit: 10000K Total Submissions: 23070 Accepted: 6760 Speci ...
- POJ 1751 Highways(最小生成树Prim普里姆,输出边)
题目链接:点击打开链接 Description The island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has ...
- POJ 1751 Highways(最小生成树&Prim)题解
思路: 一开始用Kruskal超时了,因为这是一个稠密图,边的数量最惨可能N^2,改用Prim. Prim是这样的,先选一个点(这里选1)作为集合A的起始元素,然后其他点为集合B的元素,我们要做的就是 ...
- (最小生成树 Prim) Highways --POJ --1751
链接: http://poj.org/problem?id=1751 Time Limit: 1000MS Memory Limit: 10000K Total Submissions: 1150 ...
- H - Highways - poj 1751(prim)
某个地方政府想修建一些高速公路使他们每个乡镇都可以相同通达,不过以前已经修建过一些公路,现在要实现所有的联通,所花费的最小代价是多少?(也就是最小的修建长度),输出的是需要修的路,不过如果不需要修建就 ...
随机推荐
- 活用maven使web.xml可以用maven变量
活用maven使web.xml可以用maven变量 废话不多说,直接上代码 <build> <finalName>${finalWarName}</finalName&g ...
- 【解决】UEFI+GPT模式下装系统(WIN7/WIN8)
最近在家想把联想超极本重装系统,可是发现想简单了,预装WIN8的本本用的是UEFI+GPT模式,以前老毛桃装系统那一套不好用了,所以百度了一些方案,还没试,先记着. 1. WIN8 先说装WIN8,貌 ...
- Kafka系列(二)特性和常用命令
Kafka中Replicas复制备份机制 kafka将每个partition数据复制到多个server上,任何一个partition有一个leader和多个follower(可以没有),备份的个数可以 ...
- leetcode@ [51/52] N-Queens
https://leetcode.com/problems/n-queens/ class Solution { public: void dfs(vector<vector<string ...
- 视频播放(iOS开发)
视频播放 一.视频播放介绍(5种实现方案) AVPlayer 优点 可以自定义UI,进行控制 缺点 单纯的播放,没有控制UI,而且如果要显示播放界面,需要借助AVPlayerLayer,添加图层到需要 ...
- Ubuntu 12.04 wine QQ
1.首先安装最新版的wine1.52,没记错版本号应该是这个 sudo add-apt-repository ppa:ubuntu-wine/ppa sudo apt-get update sudo ...
- Count属性(行数 @)
在PS2.0中,如果返回值为空,则count也会返回空(vm.txt内容为空),如下: (gc d:\vm.txt).count 如果加上@的话,会返回0 @(gc d:\vm.txt).count ...
- 图像处理界的标准图像Lena背后的故事
今天晚上实验室的哥们问到我:“蒋志强,你知道咱们数字图像处理界标准图像Lena吗?” “当然知道啊,不就是那个512×512的美丽姐姐的标准图像么?”我不以为然的回答: “那幅图像事实上不是原始图像? ...
- Referenced file contains errors (http://www.springframework.org/schema...错误--转载
Referenced file contains errors (http://www.springframework.org/schema/beans/spring-beans-3.0.xsd). ...
- I'm back
亲爱的博友们, 请忽略这一条, 这只是我个人的一个记录.