POJ 2536 匈牙利算法

思路：最大匹配 （很裸）

// by SiriusRen
#include <cmath>
#include <cstdio>
#include <cstring>
using namespace std;
#define N 205
int n,tot=0,first
,v[N*N],next[N*N],m,s,V,vis
,fa
,ans=0;
double ax
,ay
,bx
,by
;
void add(int x,int y){v[tot]=y,next[tot]=first[x],first[x]=tot++;}
bool dfs(int x){
for(int i=first[x];~i;i=next[i])
if(!vis[v[i]]){
vis[v[i]]=1;
if(!fa[v[i]]||dfs(fa[v[i]])){
fa[v[i]]=x;return 1;
}
}
return 0;
}
int main()
{
while(~scanf("%d%d%d%d",&n,&m,&s,&V)){
tot=ans=0,memset(fa,0,sizeof(fa)),memset(first,-1,sizeof(first));
for(int i=1;i<=n;i++)scanf("%lf%lf",&ax[i],&ay[i]);
for(int i=1;i<=m;i++)scanf("%lf%lf",&bx[i],&by[i]);
for(int i=1;i<=n;i++) for(int j=1;j<=m;j++)
if(sqrt((bx[j]-ax[i])*(bx[j]-ax[i])+(by[j]-ay[i])*(by[j]-ay[i]))<=(double)s*V)add(i,n+j);
for(int i=1;i<=n;i++,memset(vis,0,sizeof(vis)))if(dfs(i))ans++;
printf("%d\n",n-ans);
}
}