【实数二分/前缀和维护】Best Cow Fences

Poj 2018 Best Cow Fences

实数二分+前缀和维护

调了一晚上， 但发现没什么注意事项orz

无输出只因eps定义成了int型QAQ哭唧唧

#include<cstdio>
#include<iostream>
using namespace std;
const int sz = 100010;
double eps = 1e-5;
int n, f;
double a[sz], b[sz], sum[sz];
bool check(double k) {
    double minn = 1e10, ans = -1e10;
    for(int i = 1; i <= n; i++)
        b[i] = a[i] - k;
    for(int i = 1; i <= n; i++)
        sum[i] = sum[i-1] + b[i];
    for(int i = f; i <= n; i++) {
        minn = min(minn, sum[i - f]);
        ans = max(ans, sum[i] - minn);
     }
     if(ans >= 0) return true;
     else return false;
}
int main() {
    scanf("%d%d", &n, &f);    
    for(int i = 1; i <= n; i++)
        scanf("%lf", &a[i]);
    double l = -1e6, r = 1e6, ans = 0;
    while(r - l > eps) {
        double mid = (l + r) / 2.0;
        if(check(mid)) l = mid;
        else r = mid;
    }
    cout<< int(r * 1000) <<endl;
    return 0;
}