题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=2768
题解:建图的对象应该是viewer,不是cats & dogs。寻找冲突的匹配,对于同一只cat||dog,viewer i喜欢 viewer j不喜欢,冲突,建立一条边。去除被viewer i hate 同时不被其他viewer like.即求最大独立集。最大独立点集== N (点数)- 最大匹配
//邻接表
#include <cstdio>
#include <cstring>
#include <vector>
#define MAXN 501
using namespace std;
vector<int> mp[MAXN];
int from[MAXN],used[MAXN];
int catnum,dognum;
struct node
{
int like,hate;
}cats[MAXN],dogs[MAXN];
int match(int x)
{
int i,temp;
for(i=0;i<mp[x].size();++i)
{
temp=mp[x][i];
if(!used[temp])
{
used[temp]=1;
if(from[temp]==-1||match(from[temp]))
{
from[temp]=x;
return 1;
}
}
}
return 0;
}
int hungary()
{
int i,sum=0;
memset(from,-1,sizeof(from));
for(i=0;i<catnum;++i)
{
memset(used,0,sizeof(used));
if(match(i))
sum++;
}
return sum;
}
int main()
{
int test,n,m,k,i,j,id1,id2,ans;
char ch1,ch2;
scanf("%d",&test);
while(test--)
{
catnum=dognum=0;
scanf("%d %d %d",&n,&m,&k);
for(i=0;i<k;++i)
{
getchar();//回车
ch1=getchar();
scanf("%d",&id1);
getchar();//空格
ch2=getchar();
scanf("%d",&id2);
if(ch1=='C')
{
cats[catnum].like=id1;
cats[catnum++].hate=id2;
}
else
{
dogs[dognum].like=id1;
dogs[dognum++].hate=id2;
}
}
for(i=0;i<catnum;++i)
{
mp[i].clear();
for(j=0;j<dognum;++j)
if(cats[i].like==dogs[j].hate||cats[i].hate==dogs[j].like)
mp[i].push_back(j);//邻接表
}
ans=hungary();
printf("%d\n",k-ans);
}
return 0;
}
//邻接矩阵
#include <stdio.h>
#include <string.h>
#define MAXN 502
int mp[MAXN][MAXN];
int from[MAXN],used[MAXN];
int catnum,dognum;
typedef struct node
{
int like,hate;
}Animal;
Animal cats[MAXN],dogs[MAXN];
int match(int x)
{
int i;
for(i=0;i<dognum;++i)
{
if(!used[i]&&mp[x][i])
{
used[i]=1;
if(from[i]==-1||match(from[i]))
{
from[i]=x;
return 1;
}
}
}
return 0;
}
int hungary()
{
int i,sum=0;
memset(from,-1,sizeof(from));
for(i=0;i<catnum;++i)
{
memset(used,0,sizeof(used));
if(match(i))
sum++;
}
return sum;
}
int main()
{
int test,n,m,k,i,j,id1,id2,ans;
char ch1,ch2;
scanf("%d",&test);
while(test--)
{
catnum=dognum=0;
scanf("%d %d %d",&n,&m,&k);
for(i=0;i<k;++i)
{
getchar();//回车
ch1=getchar();
scanf("%d",&id1);
getchar();//空格
ch2=getchar();
scanf("%d",&id2);
if(ch1=='C')
{
cats[catnum].like=id1;
cats[catnum++].hate=id2;
}
else
{
dogs[dognum].like=id1;
dogs[dognum++].hate=id2;
}
}
memset(mp,0,sizeof(mp));
for(i=0;i<catnum;++i)
{
for(j=0;j<dognum;++j)
if(cats[i].like==dogs[j].hate||cats[i].hate==dogs[j].like)
mp[i][j]=1;
}
ans=hungary();
printf("%d\n",k-ans);
}
return 0;
}