pypy3 解法, 执行用时: 1530ms, 内存消耗: 43024K, 提交时间: 2023-05-09 17:18:46

from collections import defaultdict

n = int(input())
x = [0] * (n + 1)
y = [0] * (n + 1)
for i in range(1, n + 1):
    x[i], y[i] = map(float, input().split())

ans = 0
for i in range(1, n + 1):
    mp = defaultdict(int)
    for j in range(i + 1, n + 1):
        if x[i] * y[j] - x[j] * y[i] == 0:
            continue
        nx = ((y[j] - y[i]) * y[i] * y[j] - x[i] * x[i] * y[j] + x[j] * x[j] * y[i]) / (x[j] * y[i] - x[i] * y[j])
        ny = ((x[j] - x[i]) * x[i] * x[j] - y[i] * y[i] * x[j] + y[j] * y[j] * x[i]) / (y[j] * x[i] - y[i] * x[j])
        mp[(nx, ny)] += 1
        ans = max(ans, mp[(nx, ny)])

print(ans + 1)

C++11(clang++ 3.9) 解法, 执行用时: 503ms, 内存消耗: 544K, 提交时间: 2020-07-14 16:40:37

#include<bits/stdc++.h>
using namespace std;
const int MAXN=2005;
int n,ans;
double a[MAXN],b[MAXN],x,y;
typedef pair<double,double> p;
map<p,int> mx;
int main()
{
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%lf%lf",a+i,b+i);
	for(int i=1;i<=n;i++)
	{
		mx.clear();
		for(int j=i+1;j<=n;j++)
			if(a[i]*b[j]!=a[j]*b[i])
			{
				x=((b[j]-b[i])*b[i]*b[j]-a[i]*a[i]*b[j]+a[j]*a[j]*b[i])/(a[j]*b[i]-a[i]*b[j]);
				y=((a[j]-a[i])*a[i]*a[j]-b[i]*b[i]*a[j]+b[j]*b[j]*a[i])/(b[j]*a[i]-b[i]*a[j]);
				mx[p(x,y)]++; ans=max(mx[p(x,y)],ans);
			}
	}
	printf("%d\n",ans+1);
}

C++14(g++5.4) 解法, 执行用时: 322ms, 内存消耗: 540K, 提交时间: 2020-07-14 19:41:31

#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
using namespace std;
const int maxn=2e3+9;
typedef pair<double,double> pdd;
int n;
double x[maxn],y[maxn];
map<pdd,int> res;
int main(){
	scanf("%d",&n);
	rep(i,0,n) scanf("%lf%lf",x+i,y+i);
	int ans=0;
	rep(i,0,n) {
		res.clear();
		rep(j,i+1,n){
			if(x[i]*y[j]==x[j]*y[i]) continue;
			double d=x[i]*y[j]-x[j]*y[i],d1=x[i]*x[i]+y[i]*y[i],d2=x[j]*x[j]+y[j]*y[j];
			double X=(y[i]*d2-y[j]*d1)/d,Y=(x[i]*d2-x[j]*d1)/d;
			ans=max(ans,++res[{X,Y}]);
		}
	}
	printf("%d\n",ans+1);
}