#include<bits/stdc++.h>
using namespace std;
int n,board[100001][2],dp[100001][2]; //1based, [idx][0,1]
int main(){
    int tc;
    scanf("%d",&tc);
    while(tc--){
        scanf("%d",&n);
        for(int j=0; j<2; j++){
            for(int i=1; i<=n; i++){
                scanf("%d",&board[i][j]);
            }
        }
        memset(dp,0x00,sizeof(dp));
        dp[1][0]=board[1][0],dp[1][1]=board[1][1];
        dp[2][0]=board[1][1]+board[2][0],dp[2][1]=board[1][0]+dp[2][1]; 
        int ret=0;
        for(int i=3; i<=n; i++){
            for(int j=0; j<2; j++){
                dp[i][j]=max(dp[i-1][!j],dp[i-2][!j])+board[i][j];
                ret=max(ret,dp[i][j]);
            }    
        }
        printf("%d\n",ret);
    }
}

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

MQo1CjUwIDEwIDEwMCAyMCA0MAozMCA1MCA3MCAxMCA2MAo=

1
5
50 10 100 20 40
30 50 70 10 60