HDU 1281 - 棋盘游戏 - [二分图最大匹配]

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<vector>
 4 #define MAX 203
 5 using namespace std;
 6 int n,m,k;
 7 int edge[MAX][MAX];
 8 int matching[MAX];
 9 int vis[MAX];
10 void init(){memset(edge,0,sizeof(edge));}
11 void add_edge(int u,int v){edge[u][v]=edge[v][u]=1;}
12 bool dfs(int u)
13 {
14     for(int v=1;v<=n+m;v++)
15     {
16         if(!edge[u][v]) continue;
17         if (!vis[v])
18         {
19             vis[v]=1;
20             if(!matching[v] || dfs(matching[v]))
21             {
22                 matching[v]=u;
23                 matching[u]=v;
24                 return true;
25             }
26         }
27     }
28     return false;
29 }
30 int hungarian()
31 {
32     int ret=0;
33     memset(matching,0,sizeof(matching));
34     for(int i=1;i<=n;i++)
35     {
36         if(!matching[i])
37         {
38             memset(vis,0,sizeof(vis));
39             if(dfs(i)) ret++;
40         }
41     }
42     return ret;
43 }
44 int mp[103][103],match[MAX][MAX];
45 int main()
46 {
47     int kase=0;
48     while(scanf("%d%d%d",&n,&m,&k)!=EOF)
49     {
50         memset(mp,0,sizeof(mp));
51         for(int i=1,r,c;i<=k;i++)
52         {
53             scanf("%d%d",&r,&c);
54             mp[r][c]=1;
55         }
56 
57         init();
58         for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) if(mp[i][j]) add_edge(i,j+n);
59         int max_match=hungarian();
60 
61         int cnt=0;
62         memset(match,0,sizeof(match));
63         for(int i=1;i<=n+m;i++) for(int j=n+1;j<=n+m;j++) if(matching[i]==j && matching[j]==i) match[i][j]=1;
64         for(int i=1;i<=n+m;i++)
65         {
66             for(int j=n+1;j<=n+m;j++)
67             {
68                 if(match[i][j])
69                 {
70                     edge[i][j]=0;
71                     if(hungarian()<max_match) cnt++;
72                     edge[i][j]=1;
73                 }
74             }
75         }
76 
77         printf("Board %d have %d important blanks for %d chessmen.\n",++kase,cnt,max_match);
78     }
79 }