HDU 2295 Radar（二分+重复覆盖）

来源：互联网发布：电视连接网络编辑：程序博客网时间：2024/06/05 17:09

题意：

重复覆盖经典题目，然而要浮点数二分答案，精度是个坑- -浮点数二分和整数二分还是有点不同的。我的代码跑的可能有点慢，应该是模板的关系。

代码：

////  Created by  CQU_CST_WuErli//  Copyright (c) 2016 CQU_CST_WuErli. All rights reserved.//#include <iostream>#include <cstring>#include <cstdio>#include <cstdlib>#include <cctype>#include <cmath>#include <string>#include <vector>#include <list>#include <map>#include <queue>#include <stack>#include <set>#include <algorithm>#include <sstream>#include <ctime>#define CLR(x) memset(x,0,sizeof(x))#define OFF(x) memset(x,-1,sizeof(x))#define MEM(x,a) memset((x),(a),sizeof(x))#define BUG cout << "I am here" << endl#define lookln(x) cout << #x << "=" << x << endl#define SI(a) scanf("%d",&a)#define SII(a,b) scanf("%d%d",&a,&b)#define SIII(a,b,c) scanf("%d%d%d",&a,&b,&c)#define rep(flag,start,end) for(int flag=start;flag<=end;flag++)#define Rep(flag,start,end) for(int flag=start;flag>=end;flag--)#define Lson l,mid,rt<<1#define Rson mid+1,r,rt<<1|1#define Root 1,n,1#define BigInteger bignconst int MAX_L=2005;// For BigIntegerconst int INF_INT=0x3f3f3f3f;const long long INF_LL=0x7fffffff;const int MOD=1e9+7;const double eps=1e-8;const double pi=acos(-1);typedef long long  ll;using namespace std;double mid;int n,m,k;struct P{    double x,y;    P(){}    P(double x,double y):x(x),y(y){}    bool operator < (const P& rhs) const {        return x==rhs.x?y<rhs.y:x<rhs.x;    }}city[60],radar[60];double dis(P& a,P& b){    double dx=a.x-b.x;    double dy=a.y-b.y;    return sqrt(dx*dx+dy*dy);}struct DLX {    const static int maxn=1000010;    int L[maxn],R[maxn],U[maxn],D[maxn];    int Row[maxn],Col[maxn];    int H[maxn],S[maxn];    int vis[100];    int ans;    int size;    stack<int> Ans;    void init(int m) {        for (int i=0;i<=m;i++) {            U[i]=D[i]=i;            L[i]=i-1;R[i]=i+1;            S[i]=0;        }        L[0]=m;R[m]=0;        for (int i=0;i<maxn;i++) H[i]=-1;        size=m;        ans=-1;        while (Ans.size()) Ans.pop();    }    void link(int row,int col) {        size++;        Col[size]=col;Row[size]=row;        S[col]++;        U[size]=U[col];D[size]=col;        D[U[col]]=size;        U[col]=size;        if (H[row]!=-1) {            R[size]=H[row];            L[size]=L[H[row]];            R[L[size]]=size;            L[R[size]]=size;        }        else            H[row]=L[size]=R[size]=size;    }    // exact cover    void remove(int c) {        L[R[c]]=L[c];        R[L[c]]=R[c];        for (int i=D[c];i!=c;i=D[i]) {            for (int j=R[i];j!=i;j=R[j]) {                U[D[j]]=U[j];                D[U[j]]=D[j];                S[Col[j]]--;            }        }    }    void resume(int c) {        for (int i=U[c];i!=c;i=U[i]) {            for (int j=L[i];j!=i;j=L[j]) {                U[D[j]]=j;                D[U[j]]=j;                S[Col[j]]++;            }        }        R[L[c]]=c;        L[R[c]]=c;    }    bool dfs(int cnt) {        if (ans!=-1) return true;        if (R[0]==0) {            ans=cnt;            return true;        }        int c=0;        int Min=INF_INT;        for (int i=R[0];i!=0;i=R[i]){            if (Min>S[i]) Min=S[i],c=i;            // lookln(i);        }        remove(c);        for (int i=D[c];i!=c;i=D[i]) {            Ans.push(Row[i]);            for (int j=R[i];j!=i;j=R[j]) {                remove(Col[j]);            }            if (dfs(cnt+1)) return true;            for (int j=L[i];j!=i;j=L[j]) {                resume(Col[j]);            }            Ans.pop();        }        resume(c);        return false;    }    // exact cover ends;    // multiple cover    void del(int c) {        for (int i=D[c];i!=c;i=D[i]) {            L[R[i]]=L[i];            R[L[i]]=R[i];        }    }    void rec(int c) {        for (int i=U[c];i!=c;i=U[i]) {            L[R[i]]=R[L[i]]=i;        }    }    int h() {        int ret=0;        CLR(vis);        for (int i=R[0];i!=0;i=R[i]) if (!vis[i]) {            ret++;            vis[i]=1;            for (int j=D[i];j!=i;j=D[j])                for (int k=R[j];k!=j;k=R[k])                    vis[Col[k]]=1;        }        return ret;    }    bool DFS(int cnt) {        if (cnt>k) return false;        if (cnt+h()>k) return false;        if (R[0]==0) {            // lookln(mid);            return true;        }        int c=0;        int Min=INF_INT;        for (int i=R[0];i!=0;i=R[i])            if (Min>S[i]) Min=S[i],c=i;        // lookln(c);        for (int i=D[c];i!=c;i=D[i]) {            del(i);            for (int j=R[i];j!=i;j=R[j]) del(j);            if (DFS(cnt+1)) return true;            for (int j=L[i];j!=i;j=L[j]) rec(j);            rec(i);        }        return false;    }    // multiple cover ends;}dlx;int main(int argc, char const *argv[]) {#ifdef LOCAL    freopen("C:\\Users\\john\\Desktop\\in.txt","r",stdin);    // freopen("C:\\Users\\john\\Desktop\\out.txt","w",stdout);#endif    int T;SI(T);    while(T--) {        SIII(n,m,k);        rep(i,1,n) scanf("%lf%lf",&city[i].x,&city[i].y);        rep(i,1,m) scanf("%lf%lf",&radar[i].x,&radar[i].y);        double L=0.00,R=0.00;        rep(i,1,m) rep(j,1,n) R=max(R,dis(city[j],radar[i]));        // lookln(R);        while (R-L>eps) {            mid=(L+R)/2;            // lookln(mid);            dlx.init(n);            rep(i,1,m) rep(j,1,n) {                if (dis(radar[i],city[j])<=mid) dlx.link(i,j);            }            if (dlx.DFS(0)) R=mid;            else L=mid;            // if (mid==2.5) break;        }        printf("%.6lf\n",(L+R)/2);        // lookln(dlx.size);    }    return 0;}

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