poj3714Raid(平面最近点对）

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模板

 #include <iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<stdlib.h>
 #include<vector>
 #include<cmath>
 #include<queue>
 #include<set>
 using namespace std;
 #define N 200010
 #define LL long long
 #define INF 0xfffffff
 const double eps = 1e-;
 const double pi = acos(-1.0);
 const double inf = ~0u>>;
 struct point
 {
     double x,y;
     int id;
     int flag;
     point(double x=,double y =):x(x),y(y){}
 }p[N],pp[N],py[N];
 typedef point pointt;
 pointt operator -(point a,point b)
 {
     return point(a.x-b.x,a.y-b.y);
 }
 double dis(point a,point b)
 {
     if(a.flag==b.flag) return INF;
     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
 }
 bool cmp(point a,point b)
 {
     return a.x<b.x;
 }
 bool cmpp(point a,point b)
 {
     return a.y<b.y;
 }
 void binmerge(point py[],point pp[],int l,int m,int r)
 {
     int i,j,g=l;
     for(i = l,j = m+ ; i <= m&&j <= r ;)
     if(pp[i].y<pp[j].y) py[g++] = pp[i++];
     else py[g++] = pp[j++];

     while(i<=m) py[g++] = pp[i++];
     while(j<=r) py[g++] = pp[j++];
     memcpy(pp + l, py + l, (r - l + ) *sizeof(py[]));
 }
 double binshortest(point p[],point pp[],point py[],int l,int r)
 {
     if(r-l==) return dis(p[l],p[r]);
     if(r-l==) return min(min(dis(p[l],p[r]),dis(p[l],p[l+])),dis(p[l+],p[r]));
     int mid = (l+r)>>;
     int i,j,g = l,o = mid+;
     for(i = l ; i <= r ; i++)
     {
         if(py[i].id<=mid)//按y坐标顺序将点划分到pp左半数组
         pp[g++] = py[i];
         else
         pp[o++] = py[i];//pp右半数组
     }
     double minz = min(binshortest(p,py,pp,l,mid),binshortest(p,py,pp,mid+,r));
     binmerge(py,pp,l,mid,r);
     g = l;
     for(i = l ; i <= r ; i++)
     if(fabs(py[i].x-py[mid].x)<minz) pp[g++] = py[i];
     for(i = l ; i < g ; i++)
     {
         for(j = i+ ; j < g && fabs(pp[i].y-pp[j].y)<minz; j++)
         minz = min(dis(pp[i],pp[j]),minz);
     }
     return minz;
 }
 int main()
 {
     int n,i,t;
     cin>>t;
     while(t--)
     {
         scanf("%d",&n);
         for(i = ; i < n; i++)
         {
             scanf("%lf%lf",&p[i].x,&p[i].y);
             p[i].flag = ;
         }
         for(i = n; i < n*; i++)
         {
             scanf("%lf%lf",&p[i].x,&p[i].y);
             p[i].flag = ;
         }
         n<<=;
         sort(p,p+n,cmp);
         for(i = ;i < n ;i++)
         p[i].id = i;
         memcpy(py,p,n*sizeof(py[]));
         sort(p,p+n,cmpp);
         double ans = binshortest(p,pp,py,,n-);
         printf("%.3f\n",ans);
     }
     return ;
 }