精度问题WA ON TEST 11

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#include<queue>
#include<cmath>
#include<set>
#include<map>
using namespace std;
#define int long long
const int N=3e5+5;
long double n,k,a[N],b[N],ans=0;
signed main(){
	cin>>n>>k;
	for(int i=1;i<=n;i++){
		cin>>b[i];
	}
	for(int i=n;i>=1;i--){
		if(a[i]>=b[i]){
			continue;
		}
		long double tot=ceil(abs(b[i]-a[i])*1.0/(long double)min((long long)k,i));
		for(int j=i;j>=max((long long)(i-k+1),1ll);j--){
			a[j]+=(k-i+j)*tot;
		}
		ans+=tot;
	}
	cout<<(long long)ans;
	return 0;//3283427832427893248778324873247834783873278378378328732432873897328977832472
}