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3年前刚接触ACM的时候做的这一题,交了几十次怎么写都过不了.........

今天无意中又看到了这一题,随手一写终于过了.....

Quoit Design

2
0 0
1 1
2
1 1
1 1
3
-1.5 0
0 0
0 1.5
0

0.71
0.00
0.75

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>

using namespace std;

const double eps=1e-8;
const int maxn=100100;

int n;

int dcmp(double x)
{
	if(fabs(x)<eps) return 0;
	return (x>0)?1:-1;
}

struct Point
{
	double x,y;
}p[maxn],temp[maxn];

bool cmpxy(Point a,Point b)
{
	if(dcmp(a.x-b.x)!=0)
		return dcmp(a.x-b.x)<0;
	return dcmp(a.y-b.y)<0;
}

bool cmpy(Point a,Point b)
{
	return dcmp(a.y-b.y)<0;
}

inline double square(double x)
{
	return x*x;
}

double dist(Point a,Point b)
{
	return sqrt(square(a.x-b.x)+square(a.y-b.y));
}

double Close_pair(int left,int right)
{
	double d=1e30;
	if(left==right) return d;
	if(left+1==right) return dist(p[left],p[right]);
	int mid=(left+right)/2;
	d=min(Close_pair(left,mid),Close_pair(mid+1,right));	
	int k=0;
	for(int i=left;i<=right;i++)
	{
		if(dcmp(square(p[i].x-p[mid].x)-d)<=0)
		{
			temp[k++]=p[i];
		}
	}
	sort(temp,temp+k,cmpy);
	for(int i=0;i<k;i++)	
	{
		for(int j=i+1;j<k&&dcmp(square(temp[i].y-temp[j].y)-d)<0;j++)
		{
			d=min(d,dist(temp[i],temp[j]));
		}
	}
	return d;
}

int main()
{
	while(scanf("%d",&n)!=EOF&&n)
	{
		for(int i=0;i<n;i++)
		{
			double x,y;
			scanf("%lf%lf",&x,&y);
			p[i].x=x;p[i].y=y;
		}
		sort(p,p+n,cmpxy);
		printf("%.2lf\n",Close_pair(0,n-1)/2.);
	}
	return 0;
}

HDOJ 1007 Quoit Design 最近点对

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原文地址：http://blog.csdn.net/ck_boss/article/details/41646169