hdu 1007 分治法

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

 好费劲的一题，但还是被我A了，学到不少东西，骚年继续加油吧！

 

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <math.h>
using namespace std;
struct coor
{
     double x,y;
}p[100005];

int a[100005];
int cmpx(const coor &a,const coor &b)
{
    return a.x<b.x;
}

int cmpy(const int &a,const int &b)
{
     return p[a].y<p[b].y;
}

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

inline double min(double a,double b)
{
    return a<b?a:b;
}
double merger(int low,int high)
{
     if(low+1==high)
        return dist(p[low],p[high]);
     if(low+2==high)
        return min(dist(p[low],p[high]),min(dist(p[low],p[low+1]),dist(p[low+1],p[high])));
     int mid=(low+high)>>1;
     double ans=min(merger(low,mid),merger(mid+1,high));
     int i,j,cnt=0;
     for(i=low;i<=high;++i)
     {
          if(p[i].x>=p[mid].x-ans&&p[i].x<=p[mid].x+ans)
          a[cnt++]=i;
     }
     sort(a,a+cnt,cmpy);
     for(i=0;i<cnt;++i)
     {
          for(j=i+1;j<cnt;++j)
          {
              if(p[a[j]].y-p[a[i]].y>=ans)
              break;
              ans=min(ans,dist(p[a[i]],p[a[j]]));
          }
     }
     return ans;

}
int main()
{
      int n,m,i;
      while(scanf("%d",&n)!=EOF&&n!=0)
      {
            for(i=0;i<n;++i)
            {
                  scanf("%lf%lf",&p[i].x,&p[i].y);

            }
            sort(p,p+n,cmpx);
            printf("%.2lf\n",merger(0,n-1)/2);
      }
      return 0;
}