HDU——T 1068 Girls and Boys

http://acm.hdu.edu.cn/showproblem.php?pid=1068

Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 12257    Accepted Submission(s): 5775

Problem Description

the second year of the university somebody started a study on the romantic relations between the students. The relation “romantically involved” is defined between one girl and one boy. For the study reasons it is necessary to find out the maximum set satisfying the condition: there are no two students in the set who have been “romantically involved”. The result of the program is the number of students in such a set.

The input contains several data sets in text format. Each data set represents one set of subjects of the study, with the following description:

the number of students
the description of each student, in the following format
student_identifier:(number_of_romantic_relations) student_identifier1 student_identifier2 student_identifier3 ...
or
student_identifier:(0)

The student_identifier is an integer number between 0 and n-1, for n subjects.
For each given data set, the program should write to standard output a line containing the result.

 

 

Sample Input

7 0: (3) 4 5 6 1: (2) 4 6 2: (0) 3: (0) 4: (2) 0 1 5: (1) 0 6: (2) 0 1 3 0: (2) 1 2 1: (1) 0 2: (1) 0

 

 

Sample Output

5 2

 

 

Source

Southeastern Europe 2000

 

 

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（男女没有关系）最大独立子集=总点数-最大匹配数

因为男女人数不是分开的，所以在同一集合，最大匹配数/=2；

#include <cstring>
#include <cstdio>

using namespace std;

const int N(2333);
int n,match[N];
bool map[N][N],vis[N];

bool find(int u)
{
    for(int v=0;v<n;v++)
    if(map[u][v]&&!vis[v])
    {
        vis[v]=1;
        if(!match[v]||find(match[v]))
        {
            match[v]=u;
            return true;
        }
    }
    return false;
}

inline void read(int &x)
{
    x=0; register char ch=getchar();
    for(;ch>'9'||ch<'0';) ch=getchar();
    for(;ch>='0'&&ch<='9';ch=getchar()) x=x*10+ch-'0';
}

int AC()
{
    for(int ans=0;~scanf("%d",&n);ans=0)
    {
        for(int v,u,q,i=0;i<n;i++)
        {
            read(u);
            for(read(q);q--;)
                read(v),map[u][v]=1;
        }
        for(int i=0;i<n;i++)
        {
            if(find(i)) ans++;
            memset(vis,0,sizeof(vis));
        }
        printf("%d\n",n-ans/2);
        memset(map,0,sizeof(map));
        memset(match,0,sizeof(match));
    }
    return 0;
}

int I_want_AC=AC();
int main(){;}