rt，经检验，精度在1e-16时出现误差，问如何避免

# include <bits/stdc++.h>

# define I return

# define AK 0

# define IOI ;

using namespace std;

typedef long long ll;

typedef pair <int, int> pii;
typedef pair <long double, int> pdi;
const long double pi = acos (-1);

int n, x, y, mini;

long double minx = 100, angle;

pdi a[100005];

int main () {

	ios::sync_with_stdio (0);

	cin.tie (0);

	cout.tie (0);

	cin >> n;

	for (int i = 0; i < n; ++ i)
		cin >> x >> y, a[i] = {atan2 (y, x), i + 1};

	sort (a, a + n);

	a[n] = {2 * pi + a[0].first, a[0].second};

	for (int i = 0; i < n; ++ i)
		if ((angle = a[i + 1].first - a[i].first) < minx)
			minx = angle, mini = i;
//	for (int i = 0; i < n; ++ i) cout << fixed << setprecision (16) << a[i].second << ',' << a[i + 1].second << ':' << a[i + 1].first - a[i].first << '\n';
	cout << a[mini].second << ' ' << a[mini + 1].second;

	I AK IOI

}
/*
4
-6427 -6285
-5386 -5267
-3898 7239
-3905 7252
*/

Hack.in

4
-6427 -6285
-5386 -5267
-3898 7239
-3905 7252

Hack.ans

4 3

my.out

2 1