最佳牛围栏

 

#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
int n, m;
int a[N];
double sum[N];
bool check(double mid) {
    for (int i = 1; i <= n; i++) {
        sum[i] = sum[i - 1] + a[i] - mid;
    }
    double minn = 0;
    for (int i = 0, j = m; j <= n; i++, j++) {
        minn = min(minn, sum[i]);
        if (sum[j] >= minn) {
            return true;
        }
    }
    return false;
}
int main() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    double l = 0, r = 2000;
    while (r - l > 1e-5) {
        double mid = (l + r) / 2;
        if (check(mid)) {
            l = mid;
        } else {
            r = mid;
        }
    }
    cout << (int)(r * 1000) << endl;
    return 0;
}