2016夏季练习——三分

来源：POJ3301

代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
int n;
const int MAXN = 35;
const double PI=acos(-1);
const double eps = 1e-8;
const double op = (sqrt(5)-1)/2;
const double INF = (~0U>>2);
struct Node{
	double x,y;
};

Node p[MAXN];
Node rotate(Node p ,double rad){
	Node pp;
	pp.x=cos(rad)*p.x-sin(rad)*p.y;
	pp.y=p.y*cos(rad)+p.x*sin(rad);
	return pp;
}
/*inline double grad(double st,double en)
{
	return st+op*(en-st);
}*/
double calc(double rad){
	double minx=INF;
	double miny=INF;
	double maxx=-INF;
	double maxy=-INF;
	Node pp;
	for(int i=0;i<n;i++){
		pp=rotate(p[i],rad);
		minx=min(minx,pp.x);
		miny=min(miny,pp.y);
		maxx=max(maxx,pp.x);
		maxy=max(maxy,pp.y);
	}
	return max(maxx-minx,maxy-miny);
}
bool judge(double rad1,double rad2){
	//cout<<"judge: "<<calc(rad1)<<" "<<calc(rad2)<<endl;
	return calc(rad1)>calc(rad2);
}
int main(){
	int T;
	/*cout<<(~0U>>2)<<endl;
	return 0;*/
	scanf("%d",&T);
	while(T--) {
		scanf("%d",&n);
		for(int i=0;i<n;i++){
			scanf("%lf%lf",&p[i].x,&p[i].y);
			//cout<<p[i].x<<" "<<p[i].y<<endl;
		}
		double left=0;
		double right=PI/2;
		double mid=(left+right)/2;
		double midmid=(mid+right)/2;
		while(abs(mid-midmid)>eps){
			mid=(left+right)/2;
			midmid=(right+mid)/2;
			//cout<<left<<" "<<midmid<<" "<<mid<<" "<<right<<endl;
			if(judge(mid,midmid)){
				left=mid;
			}
			else{
				right=midmid;
			}
		}
		//cout<<"mid: "<<mid<<" "<<calc(mid)<<endl;
		printf("%.2f\n",(calc(mid)*calc(mid)));
	}
	return 0;
}