题解链接：

https://acmer.blog.csdn.net/article/details/123910901

视频讲解：https://www.bilibili.com/video/BV1BY411J795

#include<iostream> #include<cmath> #include<vector> #include<algorithm> using namespace std;

struct kb{ double k; double b;

} l; vector<kb> op;

bool cmp(kb a,kb b) { if(a.k<b.k) { return 0; }else if(a.k>b.k) { return 1; }else{ if(a.b>b.b) { return 1; }else{ return 0; } } }

int main() {

for(int x1=0;x1<=19;x1++)
{
	for(int y1=0;y1<=20;y1++)
	{
		for(int x2=0;x2<=19;x2++)
		{
			for(int y2=0;y2<=20;y2++)
			{
				if(x2-x1!=0)
				{
					l.k=(double)(y2-y1)/(x2-x1);
					l.b=y2-l.k*x2;
					op.push_back(l);	
				}
				
			}
		}
	}
}
sort(op.begin(),op.end(),cmp);

int res=1;

for(auto it=op.begin()+1;it!=op.end();it++)
{
	if(abs((*it).k-(*(it-1)).k)>1e-8||abs((*it).b-(*(it-1)).b)>1e-8)
	{
		
		res++;
	} 
}

cout<<res+20;

}