HDOJ 题目1150 Machine Schedule(二分图最小点覆盖)

Machine Schedule

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 5874    Accepted Submission(s): 2958

Problem Description

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. 

 

Input

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.

 

Output

The output should be one integer per line, which means the minimal times of restarting machine.

 

Sample Input

5 5 100 1 11 1 22 1 33 1 44 2 15 2 26 2 37 2 48 3 39 4 30

 

Sample Output

3

 

Source

Asia 2002, Beijing (Mainland China)

 

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 二分图最大匹配=二分图最小点集覆盖

最小点覆盖：就是说选中一个点，就把以这个点为端点的所有边都选中了，求最少用几个点把所有的边都覆盖。

题目大意：一个任务可以处理在两台机器的任何一个特定的模式。求出最小的机器重启次数

ac代码

#include<stdio.h>#include<string.h>int n,m,k;int map[110][110],link[110],v[110];int dfs(int x){int i;for(i=0;i<m;i++){if(!v[i]&&map[x][i]){v[i]=1;if(link[i]==-1||dfs(link[i])){link[i]=x;return 1;}}}return 0;}int main(){//int n;while(scanf("%d",&n)!=EOF,n){int i,a,b,c,sum=0;memset(map,0,sizeof(map));scanf("%d%d",&m,&k);for(i=0;i<k;i++){scanf("%d%d%d",&a,&b,&c);if(b&&c)map[b][c]=1;}memset(link,-1,sizeof(link));for(i=0;i<n;i++){memset(v,0,sizeof(v));if(dfs(i))sum++;}printf("%d\n",sum);}}