OJ-Problems-Source/HDOJ/3717_autoAC.cpp

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#include<iostream>
#define maxn 50005
#define ll long long
using namespace std;
ll cnt[maxn];
ll num[maxn];
int n,k,t;
bool check(ll x)
{
ll sum_2=0,sum_1=0,sum=0,ans=0;
int j=n-1;
for(int i=n-1;i>=0;i--)
{
if(j>i)
{
while((j-i)*(j-i)>=x)
{
sum_2-=cnt[j]*(j-i-1)*(j-i-1);
sum_1-=cnt[j]*(j-i-1);
sum-=cnt[j];
j--;
}
}
sum_2+=2*sum_1+sum;
sum_1+=sum;
ll y=num[i]-sum*x+sum_2;
if(y<0)cnt[i]=0;
else cnt[i]=y/x+1;
sum+=cnt[i];
ans+=cnt[i];
}
return ans<=k;
}
int main()
{
cin>>t;
while(t--)
{
cin>>n>>k;
for(int i=0;i<n;i++)cin>>num[i];
ll l=1,r=1e12;
while(l<r)
{
ll mid=(l+r)>>1;
if(check(mid))r=mid;
else l=mid+1;
}
cout<<l<<endl;
}
return 0;
}