HDU1150(最小顶点覆盖)
2016-02-04 20:16
337 查看
Machine Schedule
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 7362 Accepted Submission(s): 3677
[align=left]Problem Description[/align]
As we all know, machine scheduling is a very classical problem in computer science and has been studied for a very long history. Scheduling problems differ widely in the nature of the constraints that must be satisfied and the type of schedule desired. Here we consider a 2-machine scheduling problem.
There are two machines A and B. Machine A has n kinds of working modes, which is called mode_0, mode_1, …, mode_n-1, likewise machine B has m kinds of working modes, mode_0, mode_1, … , mode_m-1. At the beginning they are both work at mode_0.
For k jobs given, each of them can be processed in either one of the two machines in particular mode. For example, job 0 can either be processed in machine A at mode_3 or in machine B at mode_4, job 1 can either be processed in machine A at mode_2 or in machine B at mode_4, and so on. Thus, for job i, the constraint can be represent as a triple (i, x, y), which means it can be processed either in machine A at mode_x, or in machine B at mode_y.
Obviously, to accomplish all the jobs, we need to change the machine's working mode from time to time, but unfortunately, the machine's working mode can only be changed by restarting it manually. By changing the sequence of the jobs and assigning each job to a suitable machine, please write a program to minimize the times of restarting machines.
[align=left]Input[/align]
The input file for this program consists of several configurations. The first line of one configuration contains three positive integers: n, m (n, m < 100) and k (k < 1000). The following k lines give the constrains of the k jobs, each line is a triple: i, x, y.
The input will be terminated by a line containing a single zero.
[align=left]Output[/align]
The output should be one integer per line, which means the minimal times of restarting machine.
[align=left]Sample Input[/align]
5 5 10
0 1 1
1 1 2
2 1 3
3 1 4
4 2 1
5 2 2
6 2 3
7 2 4
8 3 3
9 4 3
0
[align=left]Sample Output[/align]
3
题意:机器A有n种工作方式,B有m中工作方式,有k个工作。给定一个三元组(i,x,y)工作i可以用机器A的x工作方式完成也可以用机器B的y工作方式完成。不过,两个机器没转换一次工作方式均需要重启机器一次。问安排合适的工作次序,最少需要需要重启机器几次?
思路:将机器A的工作方式作为点独立集U,B的工作方式作为点独立集V。工作方式x到y的无向边表示工作i,则问题 转化为求二分图中最小顶点覆盖问题。
#include"cstdio" #include"cstring" #include"vector" using namespace std; const int MAXN=205; vector<int> G[MAXN]; int V,E; void add_edge(int u,int v) { G[u].push_back(v); G[v].push_back(u); } int match[MAXN]; int vis[MAXN]; bool dfs(int u) { vis[u]=1; for(int i=0;i<G[u].size();i++) { int v=G[u][i],w=match[v]; if(w==0||(!vis[w]&&dfs(w))) { match[u]=v; match[v]=u; return true; } } return false; } int binpartite_matching() { int ans=0; memset(match,0,sizeof(match)); for(int i=1;i<=V;i++) { if(!match[i]) { memset(vis,0,sizeof(vis)); if(dfs(i)) ans++; } } return ans; } int main() { while(scanf("%d",&V)!=EOF&&V) { scanf("%*d%d",&E); for(int i=0;i<MAXN;i++) G[i].clear(); for(int i=0;i<E;i++) { int u,v; scanf("%*d%d%d",&u,&v); add_edge(u,100+v); add_edge(100+v,u); } int ans=binpartite_matching(); printf("%d\n",ans); } return 0; }
相关文章推荐
- struct和typedef struct彻底明白了
- nyoj 840 吃花生
- HDU1796 How many integers can you find(容斥原理)
- LeetCode Problem:String to Integer (atoi)
- 《剑指offer》-重建二叉树
- js数组方法(总结)
- 某些论坛及语言
- RPC简介及原理
- 用html语言写一个隐藏二级菜单的菜单栏
- Java中的静态绑定和动态绑定
- LeetCode121. Best Time to Buy and Sell Stock
- 关于spring.net的面向切面编程 (Aspect Oriented Programming with Spring.NET)-切入点(pointcut)API
- android开发步步为营之93:android自定义view开发之一(验证码生成器)
- 聊聊关于软件质量的思考
- [最大生成树] BZOJ 3943 [Usaco2015 Feb]SuperBull
- 数据的输入
- 直接输出数组名的问题
- ios沙盒的应用
- LeetCode216. Combination Sum III
- 栈的应用:中缀表达式转化为后缀表达式(逆波兰表达式)