求助

#include
using namespace std;
int n,m,a[200005],dp[200005],q[200005],pos[200005]; 
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	for(int i=1;i<=n;i++) cin>>a[i];
	int head=0,tail=0;
	for(int i=1;i<=n;i++){
		dp[i]=q[head]+a[i];
		while(head<=tail&&i-pos;[head]>m-1) head++;
		while(head<=tail&&q;[tail]>=dp[i]) --tail;
		q[++tail]=dp[i];
		pos[tail]=i;
	}
	int ans=2e9;
	for(int i=n-m+1;i<=n;i++){
		ans=min(ans,dp[i]);
	}
	cout<<ans;
	return 0;
}