【NOIP2015模拟10.20】平均数
这题不可贪心,只能二分+前缀和判。
上标:
#include<cstdio>
#include<algorithm>
#define N 300010
#define db double
using namespace std;
int n,K,a[N];
db l,r,mid,mi,b[N];
bool bz;
inline int read()
{
int x=0; char c=getchar();
while (c<'0' || c>'9') c=getchar();
while (c>='0' && c<='9') x=(x<<1)+(x<<3)+(c^48),c=getchar();
return x;
}
int main()
{
freopen("average.in","r",stdin);
freopen("average.out","w",stdout);
n=read(),K=read();
for(int i=1;i<=n;i++) a[i]=read();
l=0,r=1000000;b[0]=0;
while (l+0.0001<r)
{
mid=(l+r)/2.0;
for (int i=1;i<=n;i++)
b[i]=b[i-1]+a[i]-mid;
bz=0;mi=0;
for (int i=K;i<=n;i++)
{
if (b[i]-mi>=-0.0001) {bz=1; break;}
mi=std::min(mi,b[i-K+1]);
}
if (bz) l=mid; else r=mid;
}
printf("%.10lf\n",l);
return 0;
}
转载需注明出处。