RT.

提交记录：https://www.luogu.com.cn/record/96970264

代码：

#include<bits/stdc++.h>
using namespace std;

int n,l,r;
long long a[200005],dp[400005],ans,f[400005];

int main(){
	scanf("%d%d%d",&n,&l,&r);
	for(int i=0;i<=n;i++){
		scanf("%lld",&a[i]);
	}
	int dl=1,dr=1;
	ans=-(1<<30);
	for(int i=0;i<=n+r;i++)dp[i]=-(1<<30);
	dp[0]=a[0];
	f[1]=0;
	for(int i=l;i<=n+r;i++){
		//dp[i]=-(1<<30);
		while(dl<=dr&&i-r>f[dl])dl++;
		while(dl<=dr&&dp[f[dr]]<=dp[i-l])dr--;
		f[++dr]=i-l;
		if(dl<=dr)dp[i]=dp[f[dl]]+a[i];
		//if(dp[i]!=-(1<<30))f[++dr]=i;
		//cout<<i<<" "<<f[dl]<<" "<<dp[i]<<endl;
	}
	for(int i=n+1;i<=n+r;i++)ans=max(ans,dp[i]);
	printf("%lld",ans);
	return 0;
}