Poj2239_selecting Courses (binary graph Max match)

Problem Solving Report

http://blog.csdn.net/juncoder/article/details/38154699

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Test instructions

There are 12 lessons per day. 7 days a week, a class is held for several days a week.

Ask for a maximum of a few lessons a week.

Ideas:

Think of the course as a set, the time of the class as a set, and the dichotomy.

#include <cstdio> #include <cstring> #include <iostream>using namespace Std;int n,day[10][15],mmap[            500][500],vis[500],cnt,pre[500];int dfs (int x) {for (int i=n+1;i<cnt;i++) {if (!vis[i]&&mmap[x][i]) {            Vis[i]=1; if (pre[i]==-1| |                DFS (Pre[i])) {pre[i]=x;            return 1; }}} return 0;}    int main () {int i,j,a,b,t;        while (cin>>n) {cnt=n+1;        memset (mmap,0,sizeof (mmap));        memset (Day,0,sizeof (day));        memset (pre,-1,sizeof (pre));            for (i=1;i<=n;i++) {cin>>t;                for (j=1;j<=t;j++) {cin>>a>>b;                if (!day[a][b]) {day[a][b]=cnt++;            } mmap[i][day[a][b]]=1;        }} int ans=0;            for (i=1;i<=n;i++) {memset (vis,0,sizeof (VIS));        Ans+=dfs (i);  } cout<<ans<<endl;  } return 0;} 

Selecting Courses

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 8466		Accepted: 3769

Description

It's well known it's not easy to select courses in the college, for there is usually conflict among the time of the Courses. Li Ming is a student who loves study every much, and at the beginning of each term, he always wants to select courses as M Ore as possible. Of course there should be no conflict among the courses he selects.

There is classes every day, and 7 days every week. There is hundreds of courses in the college, and teaching a course needs one class each week. To give students more convenience, though teaching a course needs only one class, a course'll be taught several times in A week. For example, a course is taught both at the 7-th class on Tuesday and 12-th class on Wednesday, you should assume that There is no difference between the both classes, and that students can select any class to go. At the different weeks, a student can even go to different class as his wish. Because there was so many courses in the college, selecting courses was not a easy job for Li Ming. As his good friends, can him?

Input

The input contains several cases. For each case, the first line contains a integer n (1 <= n <=), the number of courses in Li Ming ' s college. The following n lines represent n different courses. In each line, the first number is a integer t (1 <= T <= 7*12), the different time when students can go to study th E course. Then come t pairs of integers p (1 <= P <= 7) and q (1 <= q <=), which mean that the course would be taught At the Q-th class on the p-th day of a week.

Output

For each test case, output one integer, which is the maximum number of courses Li Ming can select.

Sample Input

51 1 12 1 1 2 21 2 22 3 2 3 31 3 3

Sample Output

4

Poj2239_selecting Courses (binary graph Max match)