HDU-1007 Quoit Design 平面最近点对

　　题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1007

　　简单裸题，测测模板，G++速度快了不少，应该是编译的时候对比C++优化了不少。。

 //STATUS:G++_AC_1703MS_5004KB
 #include <functional>
 #include <algorithm>
 #include <iostream>
 //#include <ext/rope>
 #include <fstream>
 #include <sstream>
 #include <iomanip>
 #include <numeric>
 #include <cstring>
 #include <cassert>
 #include <cstdio>
 #include <string>
 #include <vector>
 #include <bitset>
 #include <queue>
 #include <stack>
 #include <cmath>
 #include <ctime>
 #include <list>
 #include <set>
 #include <map>
 using namespace std;
 //#pragma comment(linker,"/STACK:102400000,102400000")
 //using namespace __gnu_cxx;
 //define
 #define pii pair<int,int>
 #define mem(a,b) memset(a,b,sizeof(a))
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define PI acos(-1.0)
 //typedef
 typedef __int64 LL;
 typedef unsigned __int64 ULL;
 //const
 const int N=;
 const int INF=0x3f3f3f3f;
 const int MOD=,STA=;
 const LL LNF=1LL<<;
 const double EPS=1e-;
 const double OO=1e15;
 const int dx[]={-,,,};
 const int dy[]={,,,-};
 const int day[]={,,,,,,,,,,,,};
 //Daily Use ...
 inline int sign(double x){return (x>EPS)-(x<-EPS);}
 template<class T> T gcd(T a,T b){return b?gcd(b,a%b):a;}
 template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;}
 template<class T> inline T lcm(T a,T b,T d){return a/d*b;}
 template<class T> inline T Min(T a,T b){return a<b?a:b;}
 template<class T> inline T Max(T a,T b){return a>b?a:b;}
 template<class T> inline T Min(T a,T b,T c){return min(min(a, b),c);}
 template<class T> inline T Max(T a,T b,T c){return max(max(a, b),c);}
 template<class T> inline T Min(T a,T b,T c,T d){return min(min(a, b),min(c,d));}
 template<class T> inline T Max(T a,T b,T c,T d){return max(max(a, b),max(c,d));}
 //End
 struct Node{  //id为nod排序后的编号值，index为排序前的标号值(随便自己定义)
     double x,y;
     int id,index;
     Node(){}
     Node(double _x,double _y,int _index):x(_x),y(_y),index(_index){}
 }nod[N],temp[N];

 int n;

 double dist(Node &a,Node &b)
 {
     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
 }

 bool cmpxy(Node a,Node b)  //先按x排序,然后按y排序
 {
     return a.x!=b.x?a.x<b.x:a.y<b.y;
 }

 bool cmpy(Node a,Node b)  //按y排序
 {
     return a.y<b.y;
 }

 pii Closest_Pair(int l,int r)  //返回排序后点的编号
 {
     if(l==r || l+==r)return pii(l,r);   //只有一个点或者两个点
     double d,d1,d2;
     int i,j,k,mid=(l+r)/;
     //左右两边最小距离点的编号
     pii pn1=Closest_Pair(l,mid);
     pii pn2=Closest_Pair(mid+,r);
     //左右两遍的最小距离
     d1=(pn1.first==pn1.second?OO:dist(nod[pn1.first],nod[pn1.second]));
     d2=(pn2.first==pn2.second?OO:dist(nod[pn2.first],nod[pn2.second]));
     pii ret;
     d=Min(d1,d2);
     ret=d1<d2?pn1:pn2;
     //找出在mid-d,mid+d之间的点
     for(i=l,k=;i<=r;i++){
         if(fabs(nod[mid].x-nod[i].x)<=d){
             temp[k++]=nod[i];
         }
     }
     //合并两边,求最小距离
     sort(temp,temp+k,cmpy);
     for(i=;i<k;i++){
         for(j=i+;j<k && fabs(temp[j].y-temp[i].y)<d;j++){
             if(dist(temp[i],temp[j])<d){
                 d=dist(temp[i],temp[j]);
                 ret=make_pair(temp[i].id,temp[j].id);
             }
         }
     }

     return ret;
 }

 void Init()   //初始化点
 {
     int i;
     double x,y;
     for(i=;i<n;i++){
         scanf("%lf%lf",&x,&y);
         nod[i]=Node(x,y,i);
     }
     sort(nod,nod+n,cmpxy);
     for(i=;i<n;i++)nod[i].id=i;  //排序后节点编号
 }

 int main(){
  //   freopen("in.txt","r",stdin);
     int T,i,j;
     while(~scanf("%d",&n) && n)
     {
         Init();
         pii ans=Closest_Pair(,n-);

         printf("%.2lf\n",dist(nod[ans.first],nod[ans.second])/);
     }
     return ;
 }