随机旋转148分求助

rt
两个点都是WA，说“Wrong answer on Line 1 Colomn 4, found 6, expected 5”。
怀疑是精度问题，使用了long double之后仍然WA。
代码如下：

#define _CRT_SECURE_NO_WARNINGS
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ld double
const int N = 400010;
const ld pi = 3.141592653589793238462643383279;
int n, m;
ld ans = 1e18;
struct Point
{
    ld x, y;
    Point() {};
    Point(ld _x, ld _y) { this->x = _x, this->y = _y; }
    bool operator < (const Point &a)const
    {
        return x * y < a.x *a.y;
    }
};
Point a[N];
ld dis(Point u, Point v)
{
    return (u.x - v.x) * (u.x - v.x) + (u.y - v.y) * (u.y - v.y);
}
void calc()
{
    sort(a + 1, a + 1 + n);
    for(int i = 2; i <= n; i++)
        for(int j = i - 1; j >= i - 50 && j >= 1; j--)
            ans = min(ans, dis(a[i], a[j]));
}
void spin(ld o)
{
    o = o / 180.0 * pi;
    for(int i = 1; i <= n; i++)
    {
        ld x = a[i].x, y = a[i].y;
        ld xn = x * cos(o) - y * sin(o);
        ld yn = x * sin(o) + y * cos(o);
        a[i] = { xn,yn };
    }
}
int main()
{
    const char endl = '\n';
    std::ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n;
    for(int i = 1; i <= n; i++)
        cin >> a[i].x >> a[i].y;
    calc();
    spin(rand() % 360);
    calc();
    printf("%.0lf\n", ans);
    return 0;
}