POJ1087 A Plug for UNIX

 1 #include<map>
 2 #include<cmath>
 3 #include<queue>
 4 #include<cstdio>
 5 #include<cstring>
 6 #include<iostream>
 7 using namespace std;
 8 const int N=800+10;
 9 string plug,device,plug0,plug1;
10 int n,m,k,g[N][N],match[N],used[N];
11 void floyd(int sz) { //传递闭包
12     for(int k=1; k<=sz; k++)
13         for(int i=1; i<=sz; i++)
14             for(int j=1; j<=sz; j++)
15                 g[i][j]|=(g[i][k]&&g[k][j]);
16 }
17 bool dfs(int u) {
18     for(int i=1; i<=m; i++)
19         if(!used[i]&&g[u][i]) {
20             used[i]=1;
21             if(match[i]==-1||dfs(match[i])) {
22                 match[i]=u;
23                 return true;
24             }
25         }
26     return false;
27 }
28 int hungary() {
29     int res=0;
30     memset(match,-1,sizeof(match));
31     for(int i=m+n+101; i<=m+n+101+n; res+=dfs(i++))
32         memset(used,0,sizeof(used));
33     return n-res;
34 }
35 int main() {
36     while(~scanf("%d",&m)) {
37         memset(g,0,sizeof(g));
38         map<string,int>q0,q1;//q0 for plugs and q1 for devices 
39         for(int i=1; i<=m; i++)cin>>plug,q0[plug]=i;
40         scanf("%d",&n);
41         int tmpn=m+n+100,tmpm=m;//100 is the max value of k
42         for(int i=1; i<=n; i++) {
43             cin>>device>>plug;
44             q1[device]=++tmpn;
45             if(!q0[plug]) q0[plug]=++tmpm;
46             g[q1[device]][q0[plug]]=1;
47         }
48         scanf("%d",&k);
49         for(int i=1; i<=k; i++) {
50             cin>>plug0>>plug1;
51             if(!q0[plug0]) q0[plug0]=++tmpm;
52             if(!q0[plug1]) q0[plug1]=++tmpm;
53             g[q0[plug0]][q0[plug1]]=1;//单向传递
54         }
55         floyd(tmpn);
56         printf("%d\n",hungary());
57     }
58     return 0;
59 }