【POJ2018】Best Cow Fences

problem

给定一个正整数数列A，求一个平均数最大、长度不小于L的子段。

solution

二分判定：是否存在一个长度大于L，平均数不小于二分值的子段。

codes

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
double a[100001], b[100001], sum[100001];
int main(){int N, L;cin >> N >> L;for(int i = 1; i <= N; i++) scanf("%lf", &a[i]);double eps = 1e-5;double l = -1e6, r = 1e6;while(r - l > eps){double mid = (l + r) / 2;for (int i = 1; i <= N; i++) b[i] = a[i] - mid;for (int i = 1; i <= N; i++)sum[i] = (sum[i - 1] + b[i]);double ans = -1e10;double min_val = 1e10;for (int i = L; i <= N; i++) {min_val = min(min_val, sum[i - L]);ans = max(ans, sum[i] - min_val);}if (ans >= 0) l = mid; else r = mid;}cout << int(r * 1000) << endl;
}

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【POJ2018】Best Cow Fences

problem

solution

codes

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