版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/Masqueradey/article/details/52781486
直接暴力做会超时,运用性质平面上的散点集的最远的两点距离必然在这个散点集的凸包的某两个顶点上出现即可。虽然用旋转卡壳优化一下会更加快,但是懒得学这个算法了(真是怠惰呢),,,
代码:
#include<iostream>
#include<algorithm>
using namespace std;
struct point{
int x,y;
}farm[60000],s[600000];
int top,n;
int dis(point p1,point p2){
return (p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y);
}
int multi(point p1,point p2,point p3){
return (p2.x-p1.x)*(p3.y-p1.y)-(p2.y-p1.y)*(p3.x-p1.x);
}
int cmp(point p1,point p2){
if(multi(farm[1],p1,p2)>0)return 1;
else if(multi(farm[1],p1,p2)==0&&dis(farm[1],p1)<dis(farm[1],p2))return 1;
return 0;
}
void tubao(){
int i,j,pos=1;
for(i=2;i<=n;i++)
if(farm[i].x<farm[pos].x)pos=i;
else if(farm[i].x==farm[pos].x&&farm[i].y<farm[pos].y)pos=i;
//cout<<pos<<endl;
swap(farm[1],farm[pos]);
sort(farm+2,farm+1+n,cmp);
s[1]=farm[1];
s[2]=farm[2];
top=2;
for(i=3;i<=n;i++)
{
while(multi(s[top-1],s[top],farm[i])<=0&&top>=2)top--;
s[++top]=farm[i];
}
}
int main(){
ios::sync_with_stdio(false);
int i,j,x,y,minn=0;
cin>>n;
for(i=1;i<=n;i++)cin>>farm[i].x>>farm[i].y;
tubao();
for(i=1;i<=top;i++)
for(j=i+1;j<=top;j++)
minn=max(minn,dis(s[i],s[j]));
cout<<minn<<endl;
//cout<<top<<endl;
//cout<<s[1].x<<" "<<s[1].y<<endl;
}