HDU 3691 Nubulsa Expo(全局最小割Stoer-Wagner算法)
As you know, the Expo garden is made up of many museums of different countries. In the Expo garden, there are a lot of bi-directional roads connecting those museums, and all museums are directly or indirectly connected with others. Each road has a tourist capacity which means the maximum number of people who can pass the road per second.
Because Nubulsa is not a rich country and the ticket checking machine is very expensive, the government decides that there must be only one entrance and one exit. The president has already chosen a museum as the entrance of the whole Expo garden, and it’s the Expo chief directory Wuzula’s job to choose a museum as the exit.
Wuzula has been to the Shanghai Expo, and he was frightened by the tremendous “people mountain people sea” there. He wants to control the number of people in his Expo garden. So Wuzula wants to find a suitable museum as the exit so that the “max tourists flow” of the Expo garden is the minimum. If the “max tourist flow” is W, it means that when the Expo garden comes to “stable status”, the number of tourists who enter the entrance per second is at most W. When the Expo garden is in “stable status”, it means that the number of people in the Expo garden remains unchanged.
Because there are only some posters in every museum, so Wuzula assume that all tourists just keep walking and even when they come to a museum, they just walk through, never stay.
For each test case:
The first line contains three integers N, M and S, representing the number of the museums, the number of roads and the No. of the museum which is chosen as the entrance (all museums are numbered from 1 to N). For example, 5 5 1 means that there are 5 museums and 5 roads connecting them, and the No. 1 museum is the entrance.
The next M lines describe the roads. Each line contains three integers X, Y and K, representing the road connects museum X with museum Y directly and its tourist capacity is K.
Please note:
1<N<=300, 0<M<=50000, 0<S,X,Y<=N, 0<K<=1000000
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <iostream>
using namespace std;
typedef long long LL; const int MAXN = ; LL mat[MAXN][MAXN];
LL weight[MAXN];
bool del[MAXN], vis[MAXN];;
int n, m, st; void init() {
memset(mat, , sizeof(mat));
memset(del, , sizeof(del));
} LL StoerWagner(int &s, int &t, int cnt) {
memset(weight, , sizeof(weight));
memset(vis, , sizeof(vis));
for(int i = ; i <= n; ++i)
if(!del[i]) {t = i; break; }
while(--cnt) {
vis[s = t] = true;
for(int i = ; i <= n; ++i) if(!del[i] && !vis[i]) {
weight[i] += mat[s][i];
}
t = ;
for(int i = ; i <= n; ++i) if(!del[i] && !vis[i]) {
if(weight[i] >= weight[t]) t = i;
}
}
return weight[t];
} void merge(int s, int t) {
for(int i = ; i <= n; ++i) {
mat[s][i] += mat[t][i];
mat[i][s] += mat[i][t];
}
del[t] = true;
} LL solve() {
LL ret = -;
int s, t;
for(int i = n; i > ; --i) {
if(ret == -) ret = StoerWagner(s, t, i);
else ret = min(ret, StoerWagner(s, t, i));
merge(s, t);
}
return ret;
} int main() {
while(scanf("%d%d%d", &n, &m, &st) != EOF) {
if(n == && m == && st == ) break;
init();
while(m--) {
int x, y, z;
scanf("%d%d%d", &x, &y, &z);
mat[x][y] += z;
mat[y][x] += z;
}
cout<<solve()<<endl;
}
}
HDU 3691 Nubulsa Expo(全局最小割Stoer-Wagner算法)的更多相关文章
- HDU 3691 Nubulsa Expo(全局最小割)
Problem DescriptionYou may not hear about Nubulsa, an island country on the Pacific Ocean. Nubulsa i ...
- UVALive 5099 Nubulsa Expo 全局最小割问题
B - Nubulsa Expo Time Limit:3000MS Memory Limit:0KB 64bit IO Format:%lld & %llu Submit S ...
- HDU 3691 Nubulsa Expo
无向图的最小割.套了个模板. #include<iostream> #include<cstdio> #include<cstring> #include<a ...
- UVALive 5099 Nubulsa Expo 全球最小割 非网络流量 n^3
主题链接:点击打开链接 意甲冠军: 给定n个点m条无向边 源点S 以下m行给出无向边以及边的容量. 问: 找一个汇点,使得图的最大流最小. 输出最小的流量. 思路: 最大流=最小割. 所以题意就是找全 ...
- 求全局最小割(SW算法)
hdu3002 King of Destruction Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (J ...
- 图的全局最小割的Stoer-Wagner算法及例题
Stoer-Wagner算法基本思想:如果能求出图中某两个顶点之间的最小割,更新答案后合并这两个顶点继续求最小割,到最后就得到答案. 算法步骤: --------------------------- ...
- 全局最小割StoerWagner算法详解
前言 StoerWagner算法是一个找出无向图全局最小割的算法,本文需要读者有一定的图论基础. 本文大部分内容与词汇来自参考文献(英文,需***),用兴趣的可以去读一下文献. 概念 无向图的割:有无 ...
- poj 2914(stoer_wanger算法求全局最小割)
题目链接:http://poj.org/problem?id=2914 思路:算法基于这样一个定理:对于任意s, t V ∈ ,全局最小割或者等于原图的s-t 最小割,或者等于将原图进行 Cont ...
- poj2914 Minimum Cut 全局最小割模板题
Minimum Cut Time Limit: 10000MS Memory Limit: 65536K Total Submissions: 8324 Accepted: 3488 Case ...
随机推荐
- .NET 可空值类型
Microsoft在CLR中引入了可空值类型(nullable value type)的概念. FCL中定义System.Nullable<T>类如下: [Serializable,Str ...
- JS中注意原型链的“指向”
昨天压缩Js文件时发现了项目中的一个prototype的问题代码如下所示: 1. <script> var XXX = function(){ }; var x1 = new XXX(); ...
- angularJS中controller的通信
<!DOCTYPE html> <html> <head lang="en"> <meta charset="UTF-8&quo ...
- backbone extend 源码分析
var extend = function(protoProps, staticProps) { var parent = this; var child; if (protoProps && ...
- Magento修改邮件模板内容
Magento 默认邮件模板 都是带着官方的标志和一些官方的基本信息.为了建立品牌形象我们需要把邮件模板中的所有官方信息换成自己的信息.修改步骤如下: 1.找到Magento的邮件模板文件(这里以 e ...
- 面向对象分析方法(I)
找出最关键的一些业务场景:一般通过动词来寻找,比如招聘系统中,一个应聘人投递一个职位就是一次应聘,应聘就是一个业务场景:一个学生参加某门课的考试,那么考试就是一个业务场景:一个学生去图书馆借书,那么借 ...
- centos 6.4 安装视频解码器
cd /etc/yum.repos.d/ wget http://mirrors.163.com/.help/CentOS6-Base-163.repo yum update rpm -Uhv htt ...
- linux压缩解压
zip压缩文件 zip -r filename.zip filesdir zip -r filename.zip file1 file2 file3 /usr/work/school //将file1 ...
- 非常详细的docker学习笔记
http://www.open-open.com/lib/view/open1423703640748.html 一.Docker 简介 Docker 两个主要部件: Docker: 开源的容器虚拟化 ...
- Interview with BOA
1. BFS 2. QuickSort 3. PCA, 1000 articles, so many factors, how to reduce factors. 4. newton's metho ...