RT，WA#3（好像我WA的跟别人都不一样）

#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int N=100005;
ll n,k,a[N],sum[N],dp[N],p[N];
deque<ll>q;
int main()
{
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	cin>>n>>k;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1;i<=n;i++)sum[i]=sum[i-1]+a[i];
	q.push_back(0);
	for(int i=1;i<=n;i++)
	{
		dp[i]=sum[i]+p[q.front()];
		p[i]=dp[i]-sum[i+1];
		while(q.size()&&p[q.back()]<p[i])q.pop_back();
		q.push_back(i);
		while(q.size()&&i-q.front()>k)q.pop_front();
		//for(int j=0;j<q.size();j++)cout<<q[j]<<" ";
		//cout<<endl;
	}
	cout<<dp[n];
	return 0;
}