最近点对（转）

#include 
#include 
#include 
#include 
#include 
using namespace std;
const int MAXN = 100010;
const double INF = 1e20;
struct Point
{
    double x,y;
};
double dist(Point a,Point b)
{
    return sqrt((a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y));
}
Point p[MAXN];
Point tmpt[MAXN];
bool cmpxy(Point a,Point b)
{
    if(a.x != b.x)return a.x < b.x;
    else return a.y < b.y;
}
bool cmpy(Point a,Point b)
{
    return a.y < b.y;
}
double Closest_Pair(int left,int right)
{
    double d = INF;
    if(left == right)return d;
    if(left + 1 == right)
        return dist(p[left],p[right]);
    int mid = (left+right)/2;
    double d1 = Closest_Pair(left,mid);
    double d2 = Closest_Pair(mid+1,right);
    d = min(d1,d2);
    int k = 0;
    for(int i = left; i <= right; i++)
    {
        if(fabs(p[mid].x - p[i].x) <= d)
            tmpt[k++] = p[i];
    }
    sort(tmpt,tmpt+k,cmpy);
    for(int i = 0; i