求助，why 要输出 int(r * 1000)，而不是 int(l * 1000)？

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e5 + 5;
const double eps = 1e-5;
int n, L, a[N];
double b[N];
bool check(double x) {
	for (int i = 1; i <= n; i++) b[i] = b[i - 1] + a[i] - x;
	double mn = 1e9;
	for (int i = L; i <= n; i++) {
		mn = min(mn, b[i - L]);
		if (b[i] - mn >= 0) return 1;
	}
	return 0;
}
int main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n >> L;
	for (int i = 1; i <= n; i++) cin >> a[i];
	double l = 0, r = 2000;
	while (l + eps < r) {
		double mid = (l + r) / 2;
		if (check(mid)) l = mid;
		else r = mid;
	}
	cout << int(r * 1000) << '\n';
	return 0;
}