HDU 5046

同样是二分+DLX即可。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define LL __int64
using namespace std;

const int maxn=3800;
const int maxc=65;
const int maxr=65;
const int inf=0x3f3f3f3f;
const double rinf=1e10;
int L[maxn], R[maxn], D[maxn], U[maxn], C[maxn];
int S[maxc], H[maxr], size;
int N,M,K;
struct City{
    LL x,y;
}cities[maxr];
struct Radar{
    int x,y;
}radar[maxc];
LL map[65][65];
///²»ÐèÒªSÓò
void Link(int r, int c)
{
    S[c]++; C[size]=c;
    U[size]=U[c]; D[U[c]]=size;
    D[size]=c; U[c]=size;
    if(H[r]==-1) H[r]=L[size]=R[size]=size;
    else {
        L[size]=L[H[r]]; R[L[H[r]]]=size;
        R[size]=H[r]; L[H[r]]=size;
    }
    size++;
}
void remove(int c){
    for (int i=D[c]; i!=c; i=D[i])
        L[R[i]]=L[i], R[L[i]]=R[i];
}
void resume(int c){
    for (int i=U[c]; i!=c; i=U[i])
        L[R[i]]=R[L[i]]=i;
}

int h(){///Óþ«È·¸²¸ÇÈ¥¹ÀËã¼ôÖ¦
    int ret=0;
    bool vis[maxc];
    memset (vis, false, sizeof(vis));
    for (int i=R[0]; i; i=R[i])
    {
        if(vis[i])continue;
        ret++;
        vis[i]=true;
        for (int j=D[i]; j!=i; j=D[j])
            for (int k=R[j]; k!=j; k=R[k])
                vis[C[k]]=true;
    }
    return ret;
}
 
int ans;
bool Dance(int k){
    int t=h();
     if(t+k>M) return false;                //¸ù¾Ý¾ßÌåÎÊÌâÑ¡ÔñÏÞÖÆËÑË÷Éî¶È»òÖ±½ÓÇó½â¡£  A*Ëã·¨£¬´Ë´¦Ö»Çó×îÓŽâ
    if(!R[0]){
        return true;
    }
    int c=R[0];
    for (int i=R[0]; i; i=R[i])
        if(S[i]<S[c])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);
        if(Dance(k+1)) return true;
        for (int j=L[i]; j!=i; j=L[j])
            resume(j);
        resume(i);
    }
    return false;
}
 
void initL(int x){///col is 1~x,row start from 1
//    ans=inf;
    for (int i=0; i<=x; ++i){
        S[i]=0;
        D[i]=U[i]=i;
        L[i+1]=i; R[i]=i+1;
    }///¶ÔÁбíÍ·³õʼ»¯
    R[x]=0;
    size=x+1;///ÕæÕýµÄÔªËØ´Óm+1¿ªÊ¼
    memset (H, -1, sizeof(H));
    ///markÿ¸öλÖõÄÃû×Ö
}

LL dabs(LL a){
    if(a<0) return -a;
    return a;
}

LL dist(int i,int j){
    return (dabs(cities[i].x-cities[j].x)+dabs(cities[i].y-cities[j].y));
}

void BuildLink(LL r){
    for(int i=1;i<=N;i++){
        for(int j=1;j<=N;j++){
            if(map[i][j]<=r)
            Link(i,j);
        }
    }
}

void bin(){
    LL Ans;
    LL l=0,r=20000000050ll,m;
    ans=inf;
    while(l<=r){
        m=(l+r)/2ll;
        ans=inf;
        initL(N);
        BuildLink(m);
        if(Dance(0))
        { Ans=m; r=m-1; }
        else l=m+1;
    }
    printf("%I64d\n",Ans);
}


int main(){
    int T,t=0;
    scanf("%d",&T);
    while(T--){
        scanf("%d%d",&N,&M);
        for(int i=1;i<=N;i++)
        scanf("%I64d%I64d",&cities[i].x,&cities[i].y);
        for(int i=1;i<=N;i++){
            for(int j=1;j<=N;j++){
            map[i][j]=dist(i,j);
    //    cout<<map[i][j]<<" ";
            }
        //    cout<<endl;
        }
        printf("Case #%d: ",++t);
/*        if(M==0){
            cout<<"Yes"<<endl;
            int Ans=inf;
            for(int i=2;i<=N;i++){
                if(map[1][i]<Ans) Ans=map[1][i]; 
            }
            printf("%d\n",Ans);
        }
        else*/
        bin();
    }
    return 0;
}