ZOJ 3156 Taxi 二分二分图

const int maxn=411;
const int maxm=141011;
int n,m;
double x[maxn],y[maxn];
double a[maxn][maxn];

double disTo(int i,int j) {
return sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
}
double dis[maxn*maxn];
int cnt;
double T;
VI g[maxn];
int from[maxn],tot;
bool use[maxn];
bool match(int u) {
for (int v=0;v<m;v++) {
if (a[u][v]<=T&&!use[v]) {
use[v]=true;
if (from[v]==-1||match(from[v])) {
from[v]=u;
return true;
}
}
}
return false;
}
bool C() {
memset(from,-1,sizeof from);
for (int i=0;i<n;i++) {
memset(use,0,sizeof use);
if (!match(i)) return false;
}
return true;
}
int main(){
while (~scanf("%d%d",&n,&m)) {
double V;
cnt=0;
for (int i=0;i<n;i++) scanf("%lf%lf",&x[i],&y[i]);
for (int i=0;i<m;i++) scanf("%lf%lf",&x[n+i],&y[n+i]);
scanf("%lf",&V);
for (int i=0;i<n;i++) {
for (int j=0;j<m;j++) {
a[i][j]=disTo(i,n+j)/V;
dis[cnt++]=a[i][j];
}
}
sort(dis,dis+cnt);
int L=0,R=cnt-1;
int ans=R;
while (L<=R) {
int M=(L+R)/2;
T=dis[M];
if (C()) {
ans=M;
R=M-1;
}
else L=M+1;
}
printf("%.2f\n",dis[ans]);
}
return 0;
}