Oj错题。。

#include
 
#define fst first
#define scd second
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)
#define endl '\n'
#define mems(a,x) memset(a,x,sizeof(a))
#define pii pair
 
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ldb = long double;
using db = double;
 
void solve();
 
int main(){
	//IOS;
	solve();
}
 
void solve(){
	int n;
	cin >> n;
	vector> a(n);
	map<double,int> mp;
	for( int i = 0; i < n; ++i){
		cin >> a[i][0] >> a[i][1];
		a[i][2] = i;
	}
	ldb maxx = -1, maxi = -1;
	ldb maxi1 = -1;
	vector<bool> f(n,false);
	for( int i = 0; i < n; ++i){
		for(int j = i + 1; j < n; ++j){
			ldb k = (a[j][1] - a[i][1])*1.0 / (a[j][0] - a[i][0]);
			mp[k] ++;
			if(maxx < mp[k]){
				maxi1 = maxi;
				maxx = mp[k];
				maxi = k;
			}
		}
	}
	// maxx = n * n - 1 / 2
	ll ans = 0,ans1 = 0;
	ldb k;
	//这里犯了一个大错误，只考虑到斜率相等，就认为他们在一条直线上面了。
	for ( int i = 0; i < n; ++i){
		for( int j = i + 1; j < n; ++j){
			k = (a[j][1] - a[i][1])*1.0 / (a[j][0] - a[i][0]);
			if(k == maxi){
				if(f[i] == 0 && f[j] == 0){
					ans += 2;
					f[i] = f[j] = true;
				}
				else if ( a[i][2] == 0){
					f[i] = true;
					++ans;
				}
				else if( a[j][2] == 0){
					f[j] = true;
					++ ans;
				}
				else
					continue;
			}
			if(k == maxi1){
				if(f[i] == 0 && f[j] == 0){
					ans1 += 2;
					f[i] = f[j] = true;
				}
				else if ( a[i][2] == 0){
					f[i] = true;
					++ans1;
				}
				else if( a[j][2] == 0){
					f[j] = true;
					++ ans1;
				}
				else
					continue;
			}
		}
	}
	cout  << max(ans,ans1) << endl;
}