原题 代码

#include<bits/stdc++.h>
#define ll long long
using namespace std;
ll n,ans;
ll k,sum,a[1111111];
int big;
int main(){
	cin>>n>>k;
	for(int i=1;i<=n;i++){
		int ii=0;
		cin>>ii;
		sum+=ii;
		a[i]=sum;
	}
	for(int i=1;i<=n;i++){
		if(a[i]-a[i-k]>big){
		    big=a[i];
		}	
	}
	cout<<big;
	return 0;
}
//	ios::sync_with_stdio(false);