DLX hdu2295 Radar

DLX + 二分半徑

double的二分判斷？？？

#include<cstdio>
#include <iostream>
#include <vector>
#include <cstring>
#include <algorithm>
#include <math.h>
using namespace std;

const int maxn = 55 * 55;
const int maxr = 55;
const int maxc = 55;

int U[maxn],D[maxn],L[maxn],R[maxn],C[maxn];
int H[maxr],S[maxc];
bool v[maxc];
int sz,ans;
///行編號從1開始，列編號爲1~c，結點0爲表頭結點
///注意給行和列的編號
///注意sz，ans.要自己初始化和賦值!!!
void init(int r,int c)///傳入行列數
{
    for(int i=0; i<=c; ++i)
    {
        S[i]=0;
        D[i]=U[i]=i;
        L[i+1]=i;
        R[i]=i+1;
    }
    R[c]=0;
    while(r)H[r--]=-1;
}
int geth()//??
{
    int ret=0;
    for(int c=R[0]; c; c=R[c]) v[c]=1;
    for(int c=R[0]; c; c=R[c]) if(v[c])
    {
        v[c]=0, ++ret;
        for(int i=D[c]; i!=c; i=D[i])
            for(int j=R[i]; j!=i; j=R[j])v[C[j]]=0;
    }
    return ret;
}
void remove(int c)
{
    for(int i=D[c]; i!=c; i=D[i])
        R[L[i]]=R[i],L[R[i]]=L[i];
}
void resume(int c)
{
    for(int i=U[c]; i!=c; i=U[i])
        R[L[i]]=L[R[i]]=i;
}
void Dance(int d)///第一次調用傳入0
{
    if(d+geth()>=ans)return;
    if(!R[0])
    {
        ans=d;
        return;
    }

//    int c = R[0];
//    for (i = R[0]; i; i = R[i])
//        if (S[i] < R[c]) c = i;
    int c = R[0], tmp = S[R[0]];
    for (int i = R[R[0]]; i; i = R[i])
        if (S[i] < tmp) tmp = S[c = i];

    for(int i=D[c]; i!=c; i=D[i])
    {
        remove(i);
        for(int j=R[i]; j!=i; j=R[j])remove(j);
        Dance(d+1);
        for(int j=L[i]; j!=i; j=L[j])resume(j);
        resume(i);
    }
}
void Link(int r,int c)
{
    ++S[C[++sz]=c];
    D[sz]=D[c];
    U[D[c]]=sz;
    U[sz]=c;
    D[c]=sz;
    if(H[r]<0)H[r]=L[sz]=R[sz]=sz;
    else
    {
        R[sz]=R[H[r]];
        L[R[H[r]]]=sz;
        L[sz]=H[r];
        R[H[r]]=sz;
    }
}

struct Point{
    double x, y;
    void read()
    {
        scanf("%lf%lf", &x, &y);
    }
};

Point city[55];
Point radar[55];
int T, N, M, K;
const double eps = 1e-8;
int dcmp(double x)
{
    if (fabs(x) < eps) return 0;
    if (x < 0) return -1;
    else return 1;
}
#define sqr(x) (x) * (x)
void add(int x, double r)
{
//    cout << x + 1 << " : " << endl;
    for (int i = 0; i < N; i++)
    {
//        cout << sqrt(sqr(city[i].x - radar[x].x) + sqr(city[i].y - radar[x].y)) << ' ' << r << endl;
        if (dcmp(sqrt(sqr(city[i].x - radar[x].x) + sqr(city[i].y - radar[x].y)) - r) <= 0)
        {
//            cout << i + 1<< endl;
            Link(x + 1, i + 1);
        }
    }
}
bool test(double r)
{
    init(M, N);
    sz = N;///!!!
    for (int i = 0; i < M; i++) add(i, r);
    ans = M + 1;///!!!
    Dance(0);
//    cout << ans << endl;
    return ans <= K;
}
int main()
{
    scanf("%d", &T);
    int nn, mm;
    while(T--)
    {
        scanf("%d%d%d", &N, &M, &K);
        for (int i = 0; i < N; i++) city[i].read();
        for (int i = 0; i < M; i++) radar[i].read();
        double l = 0.0, r = 1000000.0;
        while (l + eps <= r)
        {
            double m = (l + r) / 2;
            if (test(m)) r = m;
            else l = m;
        }
        printf("%.6lf\n", l);
    }
    return 0;
}