2021-10-10-Acwing1087(单调队列优化dp）

#include<iostream>
using namespace std;
#define int long long
const int N=1e5+10;
int f[N],n,k,s[N];
int q[N];
int g(int i){
    if(!i)return 0;
    return f[i-1]-s[i];
}
signed main(){
    cin>>n>>k;
    for(int i=1;i<=n;i++){
        cin>>s[i];
        s[i]+=s[i-1];
    }
    int hh=0,tt=0;
    for(int i=1;i<=n;i++){
        if(i-q[hh]>k)hh++;
        f[i]=max(f[i-1],g(q[hh])+s[i]);
        while(hh<=tt&&g(q[tt])<=g(i))tt--;
        q[++tt]=i;
    }
    printf("%lld",f[n]);
    
    
}