#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
void GordenGhost();
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t=1;
    cin>>t;
    while(t--){
        GordenGhost();
    }
    return 0;
}

void GordenGhost(){
    int n,k,sum=0,ans=0,ww=0;
    vector<int>one,two;
    cin>>n>>k;
    for (int i = 0; i < n; ++i) {
        int a;
        cin>>a;
        one.push_back(a);
    }
    for (int i = 0; i < n; ++i) {
        int a;
        cin>>a;
        two.push_back(a);
    }
    for (int i = 0; i < min(k,n); ++i) {
        sum+=one[i];
        ww= max(ww,two[i]);
        ans= max(ans,sum+ww*(k-1-i));
    }
    cout<<ans<<endl;
}

import java.util.*;
import java.io.*;
public class Main {

    static StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    public static void main(String[] args)throws Exception {
        int q = Int();
        while (q-- > 0) {
            int n = Int();
            int k = Int();
            int[] a = new int[n];
            int[] b = new int[n];
            a[0]=Int();
            for (int i = 1; i < n; i++) a[i] =a[i-1]+ Int();
            b[0]=Int();
            int max2=b[0];
            for (int i = 1; i < n; i++) max2=b[i] = Math.max(Int(),max2);
            int j=Math.min(k,a.length);
            int max=0;
            for(int i=j-1;i>=0;i--){
                int sum=0;
                int m=k-i-1;
                sum+=a[i];
                if(m==0)max= Math.max(sum,max);
                else {
                    sum += b[i] * m;
                    max = Math.max(sum, max);
                }
            }
            pw.println(max);
        }
        pw.flush();
    }
    private static int Int() throws Exception{
        st.nextToken();
        return (int)st.nval;
    }
}

```
package A;

import java.io.*;

public class Main {
    static int[] b;
    static StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    private static int Int() throws Exception{
        st.nextToken();
        return (int)st.nval;
    }
    public static void main(String[] args) throws Exception{
        int t = Int();
        while (t-- > 0){
            int n = Int();
            int k = Int();
            b = new int[n];
            int[] add = new int[n + 1];//a前n项和
            for (int i = 0; i < n; i++) {
                add[i + 1] = add[i] + Int();
            }
            for (int i = 0; i < n; i++) {
                b[i] = Int();
            }
            int x = Math.min(n, k);
            int[] b1 = new int[x];//维护一个单调数组
            for (int i = 1; i < x; i++) {
                if(b[i] > b[b1[i - 1]]){
                    b1[i] = i;
                }else b1[i] = b1[i - 1];
            }
            int ans = 0;

            if(n > k){
                for (int i = 0; i < x; i++) {
                    int temp = add[i + 1] + (k - i - 1) * b[b1[i]];
                    ans = Math.max(ans, temp);
                }
            }else {
                for (int i = 0; i < x; i++) {
                    int temp = add[i + 1] + (k - i - 1) * b[b1[i]];
                    ans = Math.max(ans, temp);
                }
            }


            pw.println(ans);

        }
        pw.flush();
    }

}

```

枚举1-n的情况

#include <vector>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include<stack>
#include<queue>
using namespace std;
#define int long long
const int MOD= 998244353;
void solve() {
    int n,k;cin >> n>>k;
   vector<int> a(n+1),b(n+1);
   for(int i=1;i<=n;i++){
    cin>>a[i];
   }
   for(int i=1;i<=n;i++){
    cin>>b[i];
   }
   int ans=0,num=0,mx=0;
   for(int i=1;i<=n&&i<=k;i++){
    num+=a[i];
    mx=max(mx,b[i]);
    ans=max(ans,num+mx*(k-i));
   }
   cout<<ans<<endl;
    return;
}
signed main()
{
    iostream::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t;cin>>t;
    while(t--){
        solve();
    }
    return 0;
}