POJ3714+最近点对

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只需要特判标记即可
#include<stdio.h>#include<string.h>#include<stdlib.h>#include<math.h>#include<algorithm>using namespace std;const double eps = 1e-8;const double inf = 9999999999.0;const int maxn =  100005;struct Point{double x,y;int flag;};Point pnt[ maxn<<1 ],temp[ maxn<<1 ];double dis( Point a,Point b ){return sqrt( (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y) );}int cmpxy( Point a,Point b ){if( a.x!=b.x )return a.x<b.x;elsereturn a.y<b.y;}int cmpx( Point a,Point b ){return a.x<b.x;}int cmpy( Point a,Point b ){return a.y<b.y;}double solve( int L,int R ){if( L==R )return inf;if( L+1==R ){if( pnt[L].flag==pnt[R].flag )return inf;elsereturn dis( pnt[L],pnt[R] );}int mid = (L+R)/2;double res,Ldis,Rdis;Ldis = solve( L,mid );Rdis = solve( mid+1,R );res = min( Ldis,Rdis );int cnt = 0;for( int i=L;i<=R;i++ ){if( fabs(pnt[i].x-pnt[mid].x)<=res ){temp[cnt++] = pnt[i];}}sort( temp,temp+cnt,cmpy );for( int i=0;i<cnt;i++ ){for( int j=i+1;j<cnt;j++ ){if( fabs( pnt[i].y-pnt[j].y )>res ) break;if( pnt[i].flag==pnt[j].flag ) continue;res = min( res,dis(pnt[i],pnt[j]) );}}return res;}int main(){int ca;scanf("%d",&ca);while( ca-- ){int n;scanf("%d",&n);for( int i=0;i<n;i++ ){scanf("%lf%lf",&pnt[i].x,&pnt[i].y);pnt[i].flag = 1;}for( int i=n;i<2*n;i++ ){scanf("%lf%lf",&pnt[i].x,&pnt[i].y);pnt[i].flag = 2;}sort( pnt,pnt+2*n,cmpxy );double Ans = solve( 0,2*n-1 );printf("%.3lf\n",Ans);}return 0;}