E44 单调队列优化DP 修剪草坪

// 单调队列+DP O(n)
#include<bits/stdc++.h>
using namespace std;

const int N=100010;
int n,k,w[N],q[N];
long long f[N],sum;

int main(){
  cin>>n>>k; k++;
  for(int i=1;i<=n;i++) cin>>w[i],sum+=w[i];
  
  long long s=1e18;
  for(int i=1,h=1,t=0; i<=n; i++){
    while(h<=t && q[h]<i-k) h++;
    while(h<=t && f[q[t]]>=f[i-1]) t--;
    q[++t]=i-1;
    f[i]=f[q[h]]+w[i];
    if(i>n-k) s=min(s,f[i]);
  }
  cout<<sum-s;
}

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N = 110000;
LL a[N], f[N];
int q[N];

int main() {
    int n, m;
    scanf("%d%d", &n, &m);
    m++;
    LL s = 0;
    for (int i = 1; i <= n; i++) {
        scanf("%lld", &a[i]);
        s += a[i];
    }
    
    int l = 1, r = 1;
    q[1] = 0;
    for (int i = 1; i <= n; i++) {
        while (l <= r && i - q[l] > m) {
            l++;
        }
        f[i] = f[q[l]] + a[i];
        
        while (l <= r && f[q[r]] >= f[i]) {
            r--;
        }
        q[++r] = i;
    }
    
    LL t = LL(1) << 60;
    for (int i = n - m + 1; i <= n; i++) {
        t = min(t, f[i]);
    }
    printf("%lld\n", s - t);
    
    return 0;
}