Problem Description
Farmer John's farm has N barns, and there are some cows that live in each barn. The cows like to drop around, so John wants to build some roads to connect these barns. If he builds roads for every pair of different barns, then he must build N * (N - 1) / 2 roads, which is so costly that cheapskate John will never do that, though that's the best choice for the cows.

Clever John just had another good idea. He first builds two transferring point S1 and S2, and then builds a road connecting S1 and S2 and N roads connecting each barn with S1 or S2, namely every barn will connect with S1 or S2, but not both. So that every pair of barns will be connected by the roads. To make the cows don't spend too much time while dropping around, John wants to minimize the maximum of distances between every pair of barns.

That's not the whole story because there is another troublesome problem. The cows of some barns hate each other, and John can't connect their barns to the same transferring point. The cows of some barns are friends with each other, and John must connect their barns to the same transferring point. What a headache! Now John turns to you for help. Your task is to find a feasible optimal road-building scheme to make the maximum of distances between every pair of barns as short as possible, which means that you must decide which transferring point each barn should connect to.

We have known the coordinates of S1, S2 and the N barns, the pairs of barns in which the cows hate each other, and the pairs of barns in which the cows are friends with each other.

Note that John always builds roads vertically and horizontally, so the length of road between two places is their Manhattan distance. For example, saying two points with coordinates (x1, y1) and (x2, y2), the Manhattan distance between them is |x1 - x2| + |y1 - y2|.

 
Input
The first line of input consists of 3 integers N, A and B (2 <= N <= 500, 0 <= A <= 1000, 0 <= B <= 1000), which are the number of barns, the number of pairs of barns in which the cows hate each other and the number of pairs of barns in which the cows are friends with each other.

Next line contains 4 integer sx1, sy1, sx2, sy2, which are the coordinates of two different transferring point S1 and S2 respectively.

Each of the following N line contains two integer x and y. They are coordinates of the barns from the first barn to the last one.

Each of the following A lines contains two different integers i and j(1 <= i < j <= N), which represent the i-th and j-th barns in which the cows hate each other.

The same pair of barns never appears more than once.

Each of the following B lines contains two different integers i and j(1 <= i < j <= N), which represent the i-th and j-th barns in which the cows are friends with each other. The same pair of barns never appears more than once.

You should note that all the coordinates are in the range [-1000000, 1000000].

 
Output
You just need output a line containing a single integer, which represents the maximum of the distances between every pair of barns, if John selects the optimal road-building scheme. Note if there is no feasible solution, just output -1. 
 
Sample Input
 4 1 1
 12750 28546 15361 32055
 6706 3887
 10754 8166
 12668 19380
 15788 16059
 3 4
 2 3
 
Sample Output
53246

思路是没有问题的,但是写的有点丑,很多地方还可以合并。一开始思路就没有问题的,但是这种题就是找bug很头疼。QwQ!

结果是maxn开了510,忘记了两倍,晕死了。

#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
const int maxn=;
const int B=;
const int R=;
const int W=;
vector<int>G[maxn];
vector<int>G2[maxn];
int dis[][maxn],Dis;//Dis是S点,T点
int x,y,x1,y1,x2,y2,a,b,n,ans;
int col[maxn],q[maxn],num;
void init()
{
for(int i=;i<=*n;i++) G[i].clear();
for(int i=;i<=*n;i++) G2[i].clear();
ans=-;
}
void scan()
{
int i;
scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
Dis=abs(x1-x2)+abs(y1-y2);
for(i=;i<=n;i++){
scanf("%d%d",&x,&y);
dis[][i]=abs(x-x1)+abs(y-y1);
dis[][i]=abs(x-x2)+abs(y-y2);
}
for(i=;i<=a;i++){
scanf("%d%d",&x,&y);
G[x].push_back(y+n);
G[x+n].push_back(y);
G[y].push_back(x+n);
G[y+n].push_back(x);
}
for(i=;i<=b;i++){
scanf("%d%d",&x,&y);
G[x].push_back(y);
G[y].push_back(x);
G[x+n].push_back(y+n);
G[y+n].push_back(x+n);
} }
bool dfs(int u)
{
if(col[u]==R) return false;
if(col[u]==B) return true;
col[u]=B;
col[u>n?u-n:u+n]=R;
q[++num]=u;
for(int i=;i<G[u].size();i++) if(!dfs(G[u][i])) return false;
for(int i=;i<G2[u].size();i++) if(!dfs(G2[u][i])) return false;
return true;
}
bool check(int x)
{
int i,j;
for(i=;i<=n;i++) if(dis[][i]>x&&dis[][i]>x) return false;
for(i=;i<=*n;i++) G2[i].clear();
for(i=;i<=*n;i++) col[i]=;
for(i=;i<=n;i++)
for(j=i+;j<=n;j++){
int d1=dis[][i]+dis[][j];
int d2=dis[][i]+dis[][j]+Dis;
int d3=dis[][i]+dis[][j];
int d4=dis[][i]+dis[][j]+Dis;
if(d1>x&&d2>x&&d3>x&&d4>x) return false;
if(d1>x){
G2[i].push_back(j+n);
G2[j].push_back(i+n);
}
if(d2>x){
G2[i].push_back(j);
G2[j+n].push_back(i+n);
}
if(d3>x){
G2[i+n].push_back(j);
G2[j+n].push_back(i);
}
if(d4>x){
G2[i+n].push_back(j+n);
G2[j].push_back(i);
}
}
for(i=;i<=*n;i++){
if(col[i]) continue;
num=;
if(!dfs(i)){
for(j=;j<=num;j++) {
col[q[j]>n?q[j]-n:q[j]+n]=W;
col[q[j]]=W;
}
if(!dfs(i>n?i-n:i+n)) return false;
}
}
return true;
}
int main()
{
while(~scanf("%d%d%d",&n,&a,&b)){
init();
int L=,R=;
scan();
while(L<=R){
int mid=(L+R)>>;
if(check(mid)){ ans=mid;R=mid-;}
else L=mid+;
}
printf("%d\n",ans);
}
return ;
}

下面这样建图有些问题,读者可以思考一下。

         if(d2<=x&&d1>x&&d3>x){
G2[i].push_back(j+n);
G2[j+n].push_back(i);
}
if(d1<=x&&d2>x&&d4>x){
G2[i].push_back(j);
G2[j].push_back(i);
}
if(d4<=x&&d3>x&&d1>x){
G2[i+n].push_back(j);
G2[j].push_back(i+n);
}
if(d3<=x&&d4>x&&d2>x){
G2[i+n].push_back(j+n);
G2[j+n].push_back(i+n);
}

HDU1815 Building roads(二分+2-SAT)的更多相关文章

  1. POJ Building roads [二分答案 2SAT]

    睡觉啦 #include <iostream> #include <cstdio> #include <cstring> #include <algorith ...

  2. poj 2749 Building roads (二分+拆点+2-sat)

    Building roads Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 6229   Accepted: 2093 De ...

  3. HDU 1815, POJ 2749 Building roads(2-sat)

    HDU 1815, POJ 2749 Building roads pid=1815" target="_blank" style="">题目链 ...

  4. Building roads

    Building roads Time Limit: 10000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Tot ...

  5. [POJ2749]Building roads(2-SAT)

    Building roads Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 8153   Accepted: 2772 De ...

  6. poj 3625 Building Roads

    题目连接 http://poj.org/problem?id=3625 Building Roads Description Farmer John had just acquired several ...

  7. BZOJ 1626: [Usaco2007 Dec]Building Roads 修建道路( MST )

    计算距离时平方爆了int结果就WA了一次...... ------------------------------------------------------------------------- ...

  8. bzoj1626 / P2872 [USACO07DEC]道路建设Building Roads

    P2872 [USACO07DEC]道路建设Building Roads kruskal求最小生成树. #include<iostream> #include<cstdio> ...

  9. bzoj 1626: [Usaco2007 Dec]Building Roads 修建道路 -- 最小生成树

    1626: [Usaco2007 Dec]Building Roads 修建道路 Time Limit: 5 Sec  Memory Limit: 64 MB Description Farmer J ...

随机推荐

  1. input propertyChange

    結合 HTML5 標準事件 oninput 和 IE 專屬事件 onpropertychange 事件來監聽輸入框值變化. oninput 是 HTML5 的標準事件,對於檢測 textarea, i ...

  2. loadrunder之脚本篇——定义全局变量

    如果参数是全局的,在脚本中的任何一个Action中都可以使用,变量一般是局部的,如果跨Action调用会出现未声明的错误. 打开Script视图中左侧Action列表中的globals.h文件,可定义 ...

  3. 使用jsp+javabean完成用户登陆功能

    User.java package com.po; public class User implements java.io.Serializable { private String usernam ...

  4. Shell编程之for和select循环

    一.for和select循环 1.for循环语法 for 变量名 in 变量取值列表 do 指令... done C语言型for循环 for ((exp1; exp2; exp3)) do 指令... ...

  5. apache2.4配置ssl

    1,yum 安装openssl和openssl-devel,httpd-devel2,生成证书(也可以从公司的证书颁发机构获取): #建立服务器密钥 openssl genrsa -des3 > ...

  6. Java public class 与 class 区别

    在编写类的时候可以使用两种定义方式: public class 定义类 class 定义类 1.public class 定义类 如果一个类声明的时候使用了public class,则类名必须与文件名 ...

  7. redis中文文档

    phpredis是php的一个扩展,效率是相当高有链表排序功能,对创建内存级的模块业务关系 很有用;以下是redis官方提供的命令使用技巧: 下载地址如下: https://github.com/ow ...

  8. utf-8,Unicode和ASCII区别

    一.ASCII 码 我们知道,计算机内部,所有信息最终都是一个二进制值.每一个二进制位(bit)有0和1两种状态,因此八个二进制位就可以组合出256种状态,这被称为一个字节(byte).也就是说,一个 ...

  9. 【P2422】良好的感觉(单调栈优化DP//奇怪的暴力)

    话说正解是单调栈优化DP,然而貌似根据某种玄学的推算,这个题暴力出解貌似也是可以的.首先,我们枚举所有的点作为最小点,然后横向展开,遇到更小的就停止...然后再操作一下,看上去时间O(N^2),然而由 ...

  10. 【转】Android PullToRefresh (ListView GridView 下拉刷新) 使用详解

    最近项目用到下拉刷新,上来加载更多,这里对PullToRefresh这控件进行了解和使用. 以下内容转载自:http://blog.csdn.net/lmj623565791/article/deta ...