Problem Description

Alice and Bob are playing a game. There are two piles of cards. There are N cards in each pile, and each card has a score. They take turns to pick up the top or bottom card from either pile, and the score of the card will be added to his total score. Alice and Bob are both clever enough, and will pick up cards to get as many scores as possible. Do you know how many scores can Alice get if he picks up first?

 

Input

The first line contains an integer T (T≤100), indicating the number of cases. 
Each case contains 3 lines. The first line is the N (N≤20). The second line contains N integer a_i (1≤a_i≤10000). The third line contains N integer b_i (1≤b_i≤10000).

 

Output

For each case, output an integer, indicating the most score Alice can get.

 

Sample Input

 

Sample Output

 

#include<iostream>
#include<algorithm>
#include<string.h>
using namespace std;
const int N=25;
int  a[N],b[N];
int dp[N][N][N][N];

int dfs(int l1,int r1,int l2,int r2,int sum)
{
    int mx=0;
    if(l1>r1&&l2>r2) return 0;
    if(dp[l1][r1][l2][r2]) return dp[l1][r1][l2][r2];
    if(l1<=r1)
    {
        mx=max(mx,sum-dfs(l1+1, r1,l2, r2,sum-a[l1]));
        mx=max(mx,sum-dfs(l1,r1-1, l2, r2,sum-a[r1]));
    }
    if(l2<=r2)
    {
        mx=max(mx,sum-dfs(l1, r1,l2+1, r2,sum-b[l2]));
        mx=max(mx,sum-dfs(l1,r1, l2, r2-1,sum-b[r2]));
    }
    dp[l1][r1][l2][r2]=mx;
    return mx;
}
int main()
{
    int t,n,sum;
    scanf("%d",&t);
    while(t--)
    {
        sum=0;
        scanf("%d",&n);
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&a[i]);
            sum+=a[i];
        }
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&b[i]);
            sum+=b[i];
        }
        memset(dp, 0, sizeof(dp));
        int ans=dfs(1,n,1,n,sum);
        cout<<ans<<endl;
        
    }
    return 0;
}