ZOJ 3156 Taxi 二分二分图

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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
",dis[ans]);
    }
    return 0;
}

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