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https://github.com/Kiritow/OJ-Problems-Source.git
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63 lines
1.4 KiB
C++
63 lines
1.4 KiB
C++
#include<iostream>
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using namespace std;
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#define N 50005
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#define esp 1e-5
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#define inf -10000000001
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double a[N],sum[N];
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double L[N],R[N];
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int q[N];
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int n,x,y;
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int head,tail;
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bool find(double ave){
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sum[0]=0;
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for(int i=1;i<=n;i++)
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sum[i]=sum[i-1]+a[i]-ave;
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head=tail=0;
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L[x-1]=inf;
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for(int i=x;i<=n;i++){
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int p=i-x;
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while(head<tail&&sum[p]<sum[q[tail-1]])
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tail--;
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q[tail++]=p;
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while(head<tail&&i-y>q[head])
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head++;
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L[i]=max(L[i-1],sum[i]-sum[q[head]]);
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}
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sum[n+1]=0;
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for(int i=n;i>0;i--)
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sum[i]=sum[i+1]+a[i]-ave;
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head=tail=0;
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R[n-x+2]=inf;
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for(int i=n-x+1;i>0;i--){
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int p=i+x;
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while(head<tail&&sum[p]<sum[q[tail-1]])
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tail--;
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q[tail++]=p;
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while(head<tail&&i+y<q[head])
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head++;
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R[i]=max(R[i+1],sum[i]-sum[q[head]]);
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}
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for(int i=x+1;i<=n-x;i++)
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if(L[i-1]+R[i+1]>=0)
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return true;
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return false;
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}
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int main(){
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int k=1;
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while(~scanf("%d%d%d",&n,&x,&y)){
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for(int i=1;i<=n;i++)
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scanf("%lf",&a[i]);
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double f=1.0,l=200000.0,ret;
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while(l-f>=esp){
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double mid=(f+l)/2;
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if(find(mid)){
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f=mid;
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ret=mid;
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}
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else
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l=mid;
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}
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printf("Case %d: %.3lf\n",k++,ret);
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}
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}
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