题解

题解
这道题在洛谷是一道绿题 题目传送门
为什么在这是黄题
AC Code

#include<bits/stdc++.h>
using namespace std;
const double P=3.1415926535;
int n,lft,rght,up,down;
bool book[10];
double r[10],sum;
int x[10],y[10];
double getDis(int xa,int ya,int xb,int yb){
	return sqrt((xa-xb)*(xa-xb)+(yb-ya)*(yb-ya));
}
void dfs(int k,double S){
	if(k>n){
		sum=max(sum,S);
		return;
	}
	for(int i=1;i<=n;i++){
		if(!book[i]){
			double tmp=x[i]-lft;
			tmp=min(tmp,(double)rght-x[i]);
			tmp=min(tmp,(double)up-y[i]);
			tmp=min(tmp,(double)y[i]-down);
			for(int j=1;j<=n;j++){
				if(book[j]){
					double dis=getDis(x[i],y[i],x[j],y[j]);
					tmp=min(tmp,dis-r[j]);
				}
			}
			if(tmp<0) tmp=0;
			r[i]=tmp;
			book[i]=true;
			dfs(k****+P*r[i]*r[i]);
			book[i]=false;
			
		}
	}
}
int main(){
	cin>>n>>lft>>up>>rght>>down;
	if(lft>rght)
		swap(lft,rght);
	if(up<down)
		swap(up,down);
	for(int i=1;i<=n;i++) cin>>x[i]>>y[i];
	dfs(1,0);
	cout<<(long long)((up-down)*(rght-lft)-sum+0.5);
	return 0;
}

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