【BZOJ】【P3707】【圈地】【题解】【乱搞】

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传送门:http://www.lydsy.com/JudgeOnline/problem.php?id=3707

黄学长真是太强了！

随机旋转坐标系,相邻的点暴力

Code:

#include<bits/stdc++.h>using namespace std;int n,sqrtn,bel[1010],cnt,L[55],R[55];struct point{double x,y;point(double _x=0,double _y=0):x(_x),y(_y){}double operator*(point o){return x*o.y-y*o.x;}bool operator<(point o)const{return x<o.x;}point operator-(point o){return point(x-o.x,y-o.y);}}p[1010];point rot(point p,double rad){return point(p.x*cos(rad)-p.y*sin(rad),p.x*sin(rad)+p.y*cos(rad));}double ans=1e100;void calc(int l,int r){for(int i=l;i<=r;i++)for(int j=i+1;j<=r;j++)for(int k=j+1;k<=r;k++)ans=min(ans,fabs((p[j]-p[i])*(p[k]-p[i]))/2);}void solve(){double rad=rand();for(int i=1;i<=n;i++)p[i]=rot(p[i],rad);sort(p+1,p+1+n);for(int i=0;i<cnt;i++)calc(L[i],R[i]);}int main(){scanf("%d",&n);sqrtn=50;cnt=n/sqrtn+(!!n%sqrtn);for(int i=1;i<=n;i++){bel[i]=i/sqrtn;if(bel[i]!=bel[i-1])R[bel[i-1]]=i-1,L[bel[i]]=i;}L[0]=1;R[cnt-1]=n;for(int i=1;i<=n;i++){scanf("%lf%lf",&p[i].x,&p[i].y);}for(int i=1;i<=100;i++)solve();printf("%.2lf\n",ans);return 0;}

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