【二分图|最大匹配】POJ-1325 Machine Schedule

Machine Schedule

Time Limit: 1000MS Memory Limit: 10000K   

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

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思路：注意如果某个作业可以工作在modeA_0或者modeB_0，那就相当于已经完成的作业。

水题，匈牙利算法模板题。

代码如下：

/*ID: j.sure.1PROG:LANG: C++*//****************************************/#include <cstdio>#include <cstdlib>#include <cstring>#include <algorithm>#include <cmath>#include <stack>#include <queue>#include <vector>#include <map>#include <string>#include <climits>#include <iostream>#define LL long longusing namespace std;const int INF = 0x3f3f3f3f;/****************************************/const int N = 222;int n, m, k, mac[N];bool G[N][N], vis[N];bool dfs(int u){for(int v = 1; v <= m; v++) {if(G[u][v] && !vis[v]) {vis[v] = true;if(mac[v] == -1 || dfs(mac[v])) {mac[v] = u;return true;}}}return false;}int match(){int ret = 0;memset(mac, -1, sizeof(mac));for(int i = 1; i <= n; i++) {memset(vis, 0, sizeof(vis));if(dfs(i)) ret++;}return ret;}int main(){#ifdef J_Sure//freopen("000.in", "r", stdin);//freopen(".out", "w", stdout);#endifwhile(scanf("%d", &n), n) {scanf("%d%d", &m, &k);memset(G, 0, sizeof(G));int ID, x, y;for(int i = 1; i <= k; i++) {scanf("%d%d%d", &ID, &x, &y);if(x*y) G[x][y] = 1;//当x或y有一个是0的时候，重启0次就可以完成该作业}int ans = match();printf("%d\n", ans);}return 0;}