poj 2536 Gopher II (二分匹配)

 1 //200K    47MS    C++    1200B    2014-06-10 07:43:56 
 2 #include<stdio.h>
 3 #include<string.h>
 4 #include<math.h>
 5 #define N 105
 6 struct node{
 7     double x,y;
 8 }gopher[N],hole[N];
 9 int g[N][N];
10 int match[N];
11 int vis[N];
12 int n,m;
13 double dist(node a,node b)
14 {
15     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
16 }
17 int dfs(int u)
18 {
19     for(int i=0;i<m;i++)
20         if(!vis[i] && g[u][i]){
21             vis[i]=1;
22             if(match[i]==-1 || dfs(match[i])){
23                 match[i]=u;
24                 return 1;
25             }
26         }
27     return 0;
28 }
29 int hungary()
30 {
31     int ret=0;
32     memset(match,-1,sizeof(match));
33     for(int i=0;i<n;i++){
34         memset(vis,0,sizeof(vis));
35         ret+=dfs(i);
36     }
37     return ret;
38 }
39 int main(void)
40 {
41     double s,v;
42     while(scanf("%d%d%lf%lf",&n,&m,&s,&v)!=EOF)
43     {
44         for(int i=0;i<n;i++)
45             scanf("%lf%lf",&gopher[i].x,&gopher[i].y);
46         for(int i=0;i<m;i++)
47             scanf("%lf%lf",&hole[i].x,&hole[i].y);
48         memset(g,0,sizeof(g));
49         for(int i=0;i<n;i++)
50             for(int j=0;j<m;j++)
51                 if(dist(gopher[i],hole[j])/v<s)
52                     g[i][j]=1;
53         printf("%d\n",n-hungary());
54     }
55     return 0;
56 }